Discussion 3: sleep disorders

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Control of Movement 5

David Sacks/Getty Images

Learning Objectives

After completing this chapter, you should be able to:

1. Draw the elements of a muscle and explain how muscle contraction occurs.

2. Differentiate between skeletal and smooth muscle.

3. Take a simple function such as bending your arm and explain the role of antagonist muscles.

4. Give examples of isometric and isotonic muscle contractions.

5. Describe the mechanisms underlying the stretch reflex, tendon reflex, withdrawal reflex, crossed extensor reflex, elimination reflexes, and sexual reflexes.

6. List several differences between the pyramidal and extrapyramidal motor systems. Describe the movement disorders associated with damage to the brain, spinal cord, motor neurons, and muscles.

Larissa was a beautiful baby with huge brown eyes and dimpled cheeks. Nearly 2 years of age, she was a bright, happy chatterbox, using full sentences to express herself. However, Larissa's motor development was abnormally slow. She couldn't sit up unassisted until she was nearly 11 months old, and she still wasn't walking when her parents brought her in for her 2-year examination. (Most babies can sit up by themselves by the age of 7 months and walk by 15 months.) The pediatrician looked concerned as she examined Larissa. She applied a firm touch to the sole of

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Larissa's right foot and frowned as Larissa's toes fanned out in response, her big toe bending upward. Then she tested Larissa's left foot. Again, the toes on her left foot fanned in response to the pediatrician's touch.

The pediatrician explained to Larissa's parents that the fanning of her toes was called a Babinski reflex and was perfectly normal in young babies. However, a Babinski reflex is normally absent in children as old as Larissa. To determine the cause of the delay in Larissa's motor development, the pediatrician ordered a number of tests for Larissa, including scans of her brain and spinal cord. MRI scans of Larissa's spinal cord revealed a tiny, fluid-filled cyst in the cervical region of her spinal cord, a condition known as syringomyelia.

The pediatrician explained that Larissa was probably born with the fluid-filled cyst in her spinal cord and that the cyst was interfering with the transmission of messages from her brain to the motor neurons in her spinal cord. Although surgery was risky, the pediatrician advised Larissa's parents to consult a pediatric neurosurgeon because the cyst could grow over time, causing Larissa to become severely disabled. Just after her second birthday, Larissa underwent surgery to destroy the cyst in her spinal cord. She began walking soon after the surgery, and her motor development continued normally after that.

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Photo 5.2 How has his partial spinal cord injury affected Kevin's movement?

Jennie Woodcock; Reflections Photolibrary/CORBIS

Photo 5.1 Fanning of the toes in response to a touch on the bottom of the foot is called a Babinski reflex. When the foot of an older child is touched, the toes flex and curl.

5.1 Muscle Structure and Function The Babinski reflex is one example of a reflex that is seen in very young infants but disappears as the baby gets older. If you firmly touch the bottom of the foot of an infant who is younger than 6 months old, the baby's toes will extend and spread apart. This fanning of the toes in response to a touch on the bottom of the foot is called a Babinski reflex. By the time the infant is approximately 6 months of age, the cerebral cortex develops inhibitory control of motor neurons in the spinal cord. This means that the cerebral cortex begins to send inhibitory messages down the spinal cord, which inhibit the Babinski reflex. Therefore, if you stroke the sole of the foot of an older child (one who is older than 6 months of age), the child's toes will flex and curl inward in response to the touch.

Clinicians make use of reflexes when testing for damage to the nervous system (Fiorentino, 1973). Adults with intact, or undamaged, nervous systems do not exhibit a Babinski reflex when touched on the sole of their foot. This is a normal response for people with healthy nervous systems. However, those with spinal cord or brain damage do not always curl their toes when tested with a firm touch to the bottom of their feet. The "Case Study" describes the case of a young man named Kevin who damaged his spinal cord in a car accident when he was 19. Touching the bottom of Kevin's foot produces a Babinski reflex. That is, Kevin's toes fan out, just like a young baby's, when the sole of his foot is stroked. Damage to Kevin's spinal cord has destroyed the axons that carried inhibitory messages to the motor neurons that control Kevin's feet. Thus, the Babinski reflex is not inhibited when the bottom of Kevin's foot is touched, and Kevin exhibits the Babinski reflex.

Case Study: Partial Spinal Cord Injury

After graduating from high school, Kevin enlisted in the U.S. Army. He completed his basic training at Fort Sill, Oklahoma, and then continued training at Fort Stewart in Georgia. On his 19th birthday, Kevin received orders to go to Afghanistan. Although his parents expressed concern about his deployment to a war zone, he was eager to go to Afghanistan with his company. One day, about 2 months after arriving in Afghanistan, Kevin was driving an armored Jeep in a convoy that was traveling from Bagram Airfield to Kabul. The convoy suddenly came under fire. The truck immediately in front of Kevin's Jeep was struck and came to an abrupt halt. Kevin tried to stop his vehicle, but it skidded on the dusty road and slammed into the disabled truck. In the impact, Kevin was flung against the steering wheel, breaking his sternum, or breastbone, and several ribs. In addition, Kevin's spinal cord was injured at the T4 level.

The damage to his spinal cord was limited to the ventral aspect. This meant that Kevin's motor function was impaired, but his sensory function was left intact. Kevin's injury is referred to as an incomplete spinal cord injury. Some axons at the T4 level, the point of injury, survived in spite of the damage, especially those in the dorsal region of Kevin's spinal cord.

Today the effects of the spinal cord damage are obvious. Kevin can stand on his legs, but he cannot walk without support. His gait is spastic, characterized by overextension of the joints in his legs. Motor function of the autonomic nervous system is also affected. For example, Kevin does not sweat any place on his body below the level of T4.

Movement is the result of muscle contractions, and muscles are controlled by the nervous system. Damage to the nervous system, then, disrupts normal muscle function. In this chapter we will examine normal muscle function and disorders that cause abnormal muscle function. We will also consider the roles of the brain and spinal cord in controlling movement, and we will compare reflexes with voluntary movement. Let's start by looking at the structure and function of muscles.

Like all body tissues, muscles are composed of cells. Each cell is called a muscle fiber (Figure 5.1). Muscle fibers are similar to all cells in that they have a nucleus, mitochondria, and other typical cellular components.

Figure 5.1: Muscles and muscle fibers Muscles are composed of cells, and each cell is called a muscle fiber.

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What causes muscle contractions? To begin to answer this question, recall that muscle fibers resemble neurons in one important aspect. Like neurons, each muscle fiber has a chemically sensitive region known as an endplate. The endplate of a muscle fiber contains receptor sites for the neurotransmitter acetylcholine. Axons from motor neurons terminate on the endplates of muscle fibers, and acetylcholine is released from the terminal buttons of the motor neurons whenever the motor neurons get excited and fire. This means that motor neurons initiate muscle contraction by releasing acetylcholine into the junction between the axon terminal button and the muscle fiber, called the neuromuscular junction (Figure 5.2). When acetylcholine binds with its receptor sites on the muscle fiber, it causes myosin and actin filaments to slide past each other, shortening the fiber (Figure 5.2).

Figure 5.2: The neuromuscular junction During a muscle contraction, actin filaments slide along the myosin filaments, shortening the muscle fiber.

Contraction of a muscle occurs when its fibers shorten. Please keep in mind that each muscle contains hundreds or thousands of muscle fibers. Each muscle fiber receives innervation from one axon, which means that each motor neuron stimulates contraction in only one muscle. However, an axon from a motor neuron often branches near its terminus, and individual branches terminate on endplates of different fibers. That is, one motor neuron can innervate many different fibers in one muscle (see Figure 5.3).

Figure 5.3: The role of muscle filaments in muscle contraction

The axons of motor neurons synapse with motor endplates on muscle fibers.

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Different Muscle Types

You learned in Chapter 2 that there are three types of muscles: skeletal, smooth, and cardiac muscles. Skeletal muscle is the muscle tissue that is connected to the bones and cartilage of the skeleton. Contraction of the skeletal muscles causes the bones of the skeleton to move. They are the muscles that are under our voluntary control and thus are innervated by the somatic nervous system. When I tap my finger on the desktop or smile at a friend, I am using skeletal muscles to perform these voluntary activities.

Smooth muscles are found in the walls of blood vessels and in the walls of many organs, including the stomach, the small and large intestines, the bladder, and the uterus. They are also found in the skin and in the ducts of glands. As you learned in Chapter 4, smooth muscles control the constriction and dilation of blood vessels and of the pupil of the eye. Smooth muscles are responsible for peristalsis, the rhythmic contractions of the digestive organs, and they also control the opening and closing of sphincters and ducts throughout the body. In general, smooth muscles contract more slowly, although more efficiently, than skeletal (or striated) muscles. However, smooth muscle contraction has not received as much study as skeletal muscle contraction. Therefore, we will limit our focus to the action of skeletal muscles in the remainder of this chapter.

Skeletal Muscle Function

Skeletal muscles are attached to the bones of the skeleton by tough strands of connective tissue known as tendons. The bones themselves are joined together at joints, which typically are enclosed in a capsule (Figure 5.4). Inside the joint capsule is a greasy fluid that allows bones to slide past each other easily as the bones are moved by contracting muscles. Many joints are structured in such a way that movement around the joint is permitted in two opposing directions only. For example, movement around the elbow joint is limited to flexion and extension of the arm (Figure 5.4). Flexion of a limb refers to a movement that bends the limb, whereas extension is a straightening of the limb.

Figure 5.4: Attachment of muscles to bones around the elbow joint

Extensor and flexor muscles are positioned on opposite sides of a joint. Flexor muscles bend the limb, and extensor muscles straighten the limb.

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Photo 5.3 An isometric contraction causes the muscles to bulge.

Two muscles on either side of the elbow joint, called the biceps and the triceps muscles, produce flexion and extension of the arm. Contraction of the biceps muscle causes the arm to bend at the elbow joint. In contrast, contraction of the triceps muscle produces extension of the arm. Muscles that produce opposite movements around a joint are called antagonists. Thus, the biceps and triceps muscles are antagonist muscles. Likewise, the muscles that open your mouth and the muscles that close it are antagonists.

Please keep in mind that muscles do their work by contracting. My arm bends because my biceps muscle contracts, and my arm straightens because my triceps muscle contracts. Muscle relaxation is a passive process. It occurs when a muscle stops contracting. Motor neurons initiate muscle contraction by releasing acetylcholine at the neuromuscular junction. When a motor neuron stops firing, the associated muscle fibers stop contracting, and muscle relaxation takes place.

Movement occurs when one or more muscles contract. For example, as you've just learned, contraction of the biceps muscle bends the arm. This type of muscle contraction is called isotonic contraction. As its name implies (iso- means "same" and -tonic means "tone" in Greek), muscle tone remains unchanged during this type of contraction. Isotonic contraction occurs when a muscle shortens in length, pulling the attached bones in the direction of the contraction.

Isometric contraction is another type of contraction. During isometric contraction, the muscle does not shorten but rather remains the same length. How does this happen? The bones remain in a fixed position during isometric contraction, so the muscle cannot shorten.

Try this out for yourself. First, contract your right biceps muscle isotonically, which will cause your arm to flex. When you do this, keep your left hand on your biceps as you bend your right arm and feel that the muscle tone does not change. Next, contract your right biceps muscle isometrically. To do this, you need to assume the stance of a bodybuilder with your right arm in a semiflexed position. After your arm is in a fixed position, continue to contract your right biceps muscle, keeping your left hand over the right biceps to monitor muscle tone. When a bodybuilder performs an isometric contraction of the biceps muscle, you can see the biceps bulge and pop out of the arm.

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5.2 Spinal Control of Movement Many movements of the arms, trunk, and legs are regulated by spinal cord mechanisms. Think about this for a moment. Consider what happens when you touch something very hot with your bare hand. You immediately jerk your hand away from the hot object, don't you? This reaction happens instantaneously. It happens so fast, in fact, that you don't have time to think about it. Your reaction occurs so quickly because the painful sensation is processed in the spinal cord. That is, the information about the painful stimulus goes directly to your spinal cord, where it is sent to the motor neurons that stimulate the contraction of muscles that pull your hand away from the painful object (Figure 5.5). It would take far too long for you to react if the information had to travel up the spinal cord to be processed in the brain and then motor directions were sent from the brain to the muscle.

These rapid, automatic responses to specific stimuli that are mediated by the spinal cord are called reflexes. Reflexes can be simple movements, or they can be postural adjustments that involve many muscles. However, reflexes always occur the same way in response to a particular stimulus.

The reflex that is described in the preceding paragraph is called the withdrawal reflex, or the flexion reflex. This reflex involves an immediate withdrawal movement that is made in response to a painful or noxious stimulus. I am so certain of the speed of this reflex that I once sat and watched my son, Jacob, at 2 years of age, stick his finger into a flame of a candle. I didn't bother to rush to his aid because I knew that his withdrawal reflex would remove his hand from the flame before I could reach him. (And it did!)

Reflexes also occur in the head and neck, but these are not typically mediated by the spinal cord. Motor nuclei in the brainstem control these reflexes. In this section we will focus solely on spinal reflexes. We will consider reflexes that occur in the head and neck in Chapter 6.

Spinal Reflexes

Review the structure of the spinal cord in Figure 5.5. Sensory information enters the spinal cord through the dorsal root, and the motor neurons are situated in the gray matter in the ventral aspect of the spinal cord. When a withdrawal reflex occurs, an axon carrying sensory information from a receptor relays this information directly to motor neurons, which respond to the information by initiating muscle contractions that cause flexion.

The withdrawal reflex is a unisynaptic reflex, involving only one synapse between the receptor and the motor neuron (uni- means “one” in Greek). Most other reflexes are polysynaptic reflexes, involving more than one synapse (poly- means “many” in Greek). Because more synapses are involved in a polysynaptic reflex than in a unisynaptic reflex, there is a greater time lapse between the introduction of the stimulus and the initiation of movement in polysynaptic reflexes. In contrast, unisynaptic reflexes occur nearly instantaneously, in less than 50 milliseconds.

Figure 5.5: The withdrawal reflex

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Interspersed among the muscle fibers in skeletal muscles are special structures called muscle spindles. A muscle spindle is composed of several short muscle fibers that are joined to a centralized structure called a nuclear bag (Figure 5.6). A neuron called a stretch receptor is located inside the nuclear bag. This stretch receptor gets excited whenever the muscle spindle is stretched.

Figure 5.6: A muscle spindle How does the muscle spindle communicate with the spinal cord?

The Stretch Reflex

Have you ever watched someone falling asleep during a lengthy presentation? As that person starts to drop off to sleep, his or her head begins to fall forward. But the head goes down only so far when it jerks back up again. This sequence might occur many times, over and over again: The head begins to sink, then it springs back up quickly, waking the napper momentarily.

Let's consider what is happening to this sleepy audience member. The head begins to fall forward because muscles in the back of the neck and shoulders lose their muscle tone as the person falls asleep. The head continues to drop until these muscles are stretched so much that stretch receptors in the muscle spindles fire. When the stretch receptors get excited, they activate motor neurons, which stimulate muscle fiber contraction to restore muscle tone. This reflex is called the stretch reflex. This reflex can be elicited whenever a muscle is stretched. A gentle tap below the kneecap, for example, stretches the extensor muscle in the leg, causing the muscle to contract and the leg to extend.

The Tendon Reflex

Recall that tendons connect muscles to bones of the skeleton. Stretch receptors, called Golgi tendon organs, are located in tendons. The purpose of a Golgi tendon organ is to provide feedback to the nervous system about muscle contraction. When a muscle contracts powerfully, the tendon that attaches the muscle to the skeleton is stretched, which stretches the Golgi tendon organ. Like all stretch receptors, Golgi tendon organs get excited when stretched. Their axons carry information about tendon stretching to the spinal cord, where they terminate on inhibitory interneurons (Figure 5.7). The overall effect of stretching the Golgi tendon organ is to inhibit muscle contraction in a muscle that is contracting too vigorously.

Figure 5.7: Golgi tendon organ reflex When excited, the Golgi tendon organs stimulate inhibitory cells in the spinal cord, which inhibit firing of motor neurons and thus inhibit contraction of the muscle.

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Photo 5.4 This cat stopped all movement to focus on something he saw that could be a potential threat to him.

Thus, two feedback systems relay information about muscle function to the spinal cord. Stretch receptors in the muscle spindles fire when the muscle relaxes and muscle fibers stretch, and the Golgi tendon organ fires when its respective muscle contracts too vigorously, stretching the tendon. The stretch receptor and the Golgi tendon organ stimulate opposite effects in the spinal cord. The stretch receptor in the muscle spindles produces muscle contraction. The Golgi tendon organ, in contrast, inhibits the firing of motor neurons, causing a decrease in muscle contraction. Together, these two feedback systems maintain the correct muscle tone necessary for optimum muscle function.

These two feedback systems also send information to the brain about the contraction and relaxation of muscles in the body. This information allows the brain to plan future movements based on the present state of the muscles. In addition, information from the muscles, particularly information from contracting muscles, can affect neurotransmitter function. For example, repetitive muscle contractions increase serotonin activity in the brain (see the "For Further Thought" box).

For Further Thought: Movement and the Raphe Nucleus

An area in the hindbrain called the raphe nucleus releases serotonin when stimulated. Barry Jacobs (1994; Jacobs & Fornal, 1997, 1999) has demonstrated that the activity of these serotonin neurons is closely related to motor activity. For example, some serotonin neurons in the raphe nucleus begin to fire right before a movement is initiated. In addition, many serotonin neurons increase their firing rate as the rate of muscle contractions increases. If a person walks rapidly, neurons in the raphe nucleus fire faster than if the same person walks at a more leisurely pace. This is especially true for repetitive movements like chewing or running.

Most of Jacobs's experiments have focused on the activity of neurons in the raphe nuclei of cats because in the past others have studied this area of the cat's brain, and its properties are well known. Jacobs observed that, when a cat runs on a treadmill, serotonin neurons in

the raphe nucleus fire at the same rate as the animal's gait. These neurons appear to be associated with gross motor functions rather than fine motor control. Thus, neurons in the raphe nucleus appear to enable gross movements of the torso and limbs but not movements of the eyes or fingers.

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When a cat hears a sudden noise, such as the slamming of a door, the cat stops what it is doing and turns toward the source of the sound to determine its significance. This "what is it?" reaction is called an orienting response. During an orienting response, when the cat stops all movement to concentrate on a particular stimulus, serotonin neurons in the raphe nucleus do not fire. These same neurons become active again when the individual begins to move once more. Hence, serotonin neurons in the raphe nucleus increase their firing rate when large muscle groups are contracting and decrease their firing rate when movement ceases or when the individual makes a "what is it?" response to an environmental distraction.

Other Spinal Reflexes

The importance of reflexes has been recognized for centuries. Investigators in the 17th and 18th centuries studied and cataloged most of the reflexes that are known today (Swazey, 1969). For example, in the mid-1700s Robert Whytt, at the University of Edinburgh, studied spinal reflexes in decapitated frogs and tortoises. You see, frogs without heads are frogs without brains, which means that any elicited behavior in these specially prepared subjects is mediated by the spinal cord. Whytt studied a number of reflexes that could be produced in headless frogs, including the withdrawal reflex and the scratch reflex. As its name implies, the scratch reflex is a scratching movement made by one of the frog's limbs when the frog's skin is tickled. Stimulation of sensory receptors on the frog's skin is translated into action potentials that travel down axons to the spinal cord, where they excite motor neurons that initiate contractions in muscles that produce scratching movements by the frog's limb. This scratching behavior occurs even when the brain is absent.

Probably the most important and most comprehensive study of reflexes was conducted by the British physician and scientist Sir Charles Scott Sherrington. From 1884 to 1935 Sherrington studied many reflexes, including the withdrawal reflex, the scratch reflex, and the knee jerk reflex, in monkeys, dogs, and cats. He is credited with introducing the term synapse.

The Crossed Extensor Reflex

One spinal reflex that Sherrington studied intensively is the crossed extensor reflex. This reflex is an example of Sherrington's concept of the integrative action of neurons because it typically occurs in conjunction with another reflex, the withdrawal reflex. Consider what happens when you step on a sharp object when walking in your bare feet. Immediately, the involved leg flexes to withdraw the injured foot from the sharp object. This is the withdrawal reflex. But what about the other leg? If one leg is flexed, it is important that the other leg remain extended. Otherwise, you will tumble to the floor.

The crossed extensor reflex is stimulated by the onset of the withdrawal reflex. The sensory receptor that initiates the withdrawal reflex also excites interneurons that cross the midline of the spinal cord (Figure 5.8). These interneurons, in turn, excite the motor neurons that innervate extensor muscles in the opposite leg. As a result, when one limb is withdrawn from a noxious stimulus, the other limb extends to support the weight of the body.

Figure 5.8: The crossed extensor reflex A painful stimulus to one limb causes flexion of that limb (withdrawal reflex) and extension of the opposite limb (crossed extensor reflex).

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Urination and Defecation

No one has to teach babies how to soil their diapers. Their elimination functions happen naturally. That's because these functions are under spinal control. Spinal animals, whose brains have been surgically severed from their spinal cords, continue to defecate and urinate, even assuming typical elimination positions. In spinal animals and in young infants, urination and defecation are caused by stretch reflexes. Let's consider the urination and defecation reflexes separately.

The organ that collects urine, called the bladder, is lined with smooth muscle. Like all muscles, the muscle in the bladder wall contains stretch receptors. As the bladder fills with urine, the wall of the bladder becomes stretched, causing the stretch receptors to fire. The axons of these stretch receptors terminate on motor neurons in the spinal cord that control bladder muscles. Stretching of stretch receptors in the bladder produces contraction of the bladder muscle, which forces urine out of the body through a passageway called the urethra. Thus, the bladder empties as a result of a stretch reflex.

Defecation involves a stretch reflex, too. The large intestine, including the region (called the rectum) closest to the anus, is also lined with smooth muscles and stretch receptors. As the rectum fills with feces, the walls of the rectum stretch, causing stretch receptors to fire. The stretch receptors stimulate motor neurons in the spinal cord that initiate contraction of rectal muscles, expelling feces from the body.

Toilet training takes urination and defecation out of reflexive control and places it under conscious control. A child being toilet trained learns to use skeletal muscles to open and close the sphincter muscles of the bladder and anus. This training cannot be done with a very young child because the frontal lobes are not developed enough to take control of bladder and bowel function.

People with spinal cord injuries typically have incomplete communication between the brain and neurons in the spinal cord. Often, following the injury, they lose conscious control of their bladder and bowels. However, the stretch reflexes that produce urination and defecation remain intact. Some people with spinal cord injuries can learn to control bladder function by taking advantage of the intact stretch reflex in the bladder. For example, the bladder wall can be stretched by tugging on the skin of the abdomen. Thus, people with spinal cord injuries can initiate urination by stretching the abdominal wall.

Sexual Reflexes

Many of the components of sexual activity, including erection of the penis and ejaculation, are under spinal control (Chéhensse et al., 2013). Adequate stimulation will produce penile erection in men with spinal cord injuries and in male animals whose brains have been surgically separated from their spinal cords. Continued stimulation will induce ejaculation of semen in these male subjects. Sensory receptors associated with the penis

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excite motor neurons in the sacral area of the spinal cord that cause dilation of blood vessels, producing erection of the penis. Genital receptors also excite motor neurons that cause the rhythmic contraction of muscles associated with ejaculation in the male and orgasmic response in the female.

Some sexual response can be brought under conscious control. For example, thinking erotic thoughts can produce sexual excitement leading to penile erection in the man or engorgement of the clitoris and vaginal lubrication in the woman. However, these responses can also be stimulated reflexively and are difficult, if not impossible, to stop after they have begun. For that reason, premature ejaculation cannot be halted when it occurs, because the motor neurons that initiate the ejaculatory muscle contractions have been excited reflexively. A man who is trying to prevent premature ejaculation must do so by sending inhibitory signals from his brain down to the motor neurons in his spinal cord. Another way to control premature ejaculation is the use of anesthetic creams that are applied to the genital area to reduce sensation in that area and thus decrease stimulation of sensory neurons that excite the ejaculatory motor neurons.

We have examined a number of reflexes that involve sensory neurons in the peripheral nervous system and motor neurons in the spinal cord. These reflexes serve to protect the body, to produce postural adjustments, or to support important biological functions such as respiration, elimination, and reproduction. All of these reflexes take place without prompting from higher brain structures and do not require conscious control. However, you should keep in mind that motor neurons receive innervation both from the peripheral nervous system and from the brain. That is, skeletal muscles that are under reflexive control can also be brought under conscious control. In the final sections of this chapter, we will look at how the brain controls movement.

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5.3 Control of Movement by the Brain The brain controls movement by means of two motor systems: the pyramidal motor system and the extrapyramidal motor system. These two systems arise from different regions of the brain, and each has many distinguishing features, which we will examine. However, these systems do not act independently because there is a good deal of communication between the pyramidal and extrapyramidal systems. In addition, both systems terminate on motor neurons, the final common path to the skeletal muscles.

The Pyramidal Motor System

The pyramidal motor system arises from the primary motor cortex in the frontal lobe (Figure 5.9). It sends information to the motor neurons by way of axons that leave the primary motor cortex and extend without synapsing to the appropriate motor neurons. From the primary motor cortex to the motor neurons in the spinal cord, the axons of the pyramidal system are bundled together in a tract known as the corticospinal tract. Look at this term: corticospinal tract. This is a tract that runs from the cerebral cortex (cortico) to the spinal cord.

Recall that the left hemisphere of the brain controls the right side of the body and that the right hemisphere controls the left side of the body. This means that the corticospinal tracts arising from the left and right hemispheres have to cross over to the other side of the brain. The axons from the left primary motor cortex cross over to the right side of the brain, and those from the right primary motor cortex cross over to the left side, in pyramid- shaped structures on the ventral surface of the medulla. The pyramidal system gets its name from these pyramids in the medulla where the crossover of the corticospinal tract occurs.

Figure 5.9: The motor cortex in the frontal lobe Neurons in the motor cortex stimulate motor neurons that control specific muscles in the body.

The primary motor cortex is organized topographically, as you learned in Chapter 1. Each muscle in the body is controlled by neurons located in specific places in the primary motor cortex. Figure 5.9 illustrates the location of neurons in the primary motor cortex of a chimpanzee that control particular body parts, the result of research conducted by Sherrington and his colleague, Grunbaum, in 1901 and 1902. Recall from Chapter 1 that Fritsch and Hitzig mapped the primary motor cortex of the dog in 1863 and that Penfield mapped the human primary motor cortex in the 1940s. Research conducted in many species (for example, Sherrington and Grunbaum studied the primary motor cortex of the chimpanzee, orangutan, and gorilla) confirms that the primary motor cortex is organized in such a way that the location of the neurons is essentially the same for all mammalian species, with neurons at the top of the primary motor cortex controlling the feet of the hind limbs and neurons at the bottom of the primary motor cortex controlling the face and mouth.

The function of the pyramidal motor system is fine motor control of skeletal muscles. Using scissors requires fine motor control of the muscles of the hands and fingers, for example. Neurons in the primary motor cortex organize the movements necessary to open and close scissors and send commands to the appropriate motor neurons in the spinal cord. Under direction of the primary motor cortex, these motor neurons stimulate muscles in the hand, producing movements that open and close the scissors smoothly and accurately. Whenever you learn a new motor task that requires fine motor control, the primary motor cortex directs the motor neurons, thereby regulating the muscle contractions needed to produce the new movement.

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Photo 5.5 A baby learning to sit is a function of the extrapyramidal motor system.

The Extrapyramidal Motor System

The function of the extrapyramidal motor system is to coordinate gross movements and postural adjustments. This system generally develops before the pyramidal system because gross motor control is learned before fine motor control. For example, children learn to patty-cake before they learn to hold a crayon. In addition, not all gross movements develop at the same time. A baby learns to hold her head upright before she masters the ability to sit, and she learns to sit before she stands.

The extrapyramidal system arises from many parts of the brain, including the cerebral cortex, the thalamus, the cerebellum, the basal ganglia, and the reticular formation. As its name implies, the extrapyramidal system is distributed outside the pyramidal system and does not pass through the pyramids in the medulla (extra- means "outside" in Latin). And, unlike the pyramidal system, the extrapyramidal system synapses profusely, permitting much intercommunication among the structures in the forebrain, midbrain, and hindbrain that comprise the extrapyramidal motor system. The basal ganglia and the cerebellum perhaps play the most important roles in the extrapyramidal motor system. Let's examine the roles of these structures separately.

The Cerebellum

As you learned in Chapter 4, the function of the cerebellum is to coordinate movement in response to sensory stimuli. The cerebellum receives sensory information from muscles and tendons, from the reticular formation, from the inner ear, and from the eyes, nose, and ears. The muscles and tendons inform the cerebellum about the state of all the muscles in the body. Therefore, the cerebellum knows which muscles are contracted and which are relaxed before it sends out commands to motor neurons.

The reticular formation responds whenever the nervous system is exposed to a new or important stimulus. It relays information about the important stimulus to the cerebellum, and the cerebellum organizes the response. For example, when my reticular formation detects that my name has been spoken, it alerts my cerebellum. In response, my cerebellum stops my ongoing behavior and turns my head in the direction where my name was spoken. From the inner ear, the cerebellum gets information about balance. The cerebellum coordinates muscle contractions to restore balance whenever we start to fall. The receptors in the eyes, ears, and nose all send information to the cerebellum about the presence of objects in the environment. After communicating with the cerebrum and the basal ganglia, the cerebellum coordinates movements toward or away from those objects.

No one is certain exactly how the cerebellum coordinates movement. Undoubtedly, accurate movements require that both the force and timing of muscle contractions are carefully controlled. And, research with patients with cerebellar injuries indicates that the cerebellum is intimately involved in regulating the force and timing of muscle contractions (Kwon & Park, 2011; Wickelgren, 1998b).

The organization of the cerebellum gives us some clues about how it might coordinate movement (Figure 5.10). The cerebellum's outer layer, called the cerebellar cortex, appears to govern coordination of movement (Brooks & Thach, 2011). The cerebellar cortex contains five types of neurons (Purkinje, Golgi, stellate, basket, and granule cells), but only the axons of Purkinje cells carry information out of the cerebellum. Each Purkinje cell in the cerebellar cortex is believed to control one specific muscle in the body. Linking the Purkinje cells are millions of parallel axons that run through the cerebellar cortex. The parallel axons are thought to activate certain muscles simultaneously, producing coordinated movement.

Figure 5.10: Organization of the cerebellum The cerebellar cortex contains a number of different neurons, including Purkinje, stellate, basket, granular, and Golgi cells. The Purkinje cells carry information out of the cerebellum.

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The cerebellum is especially adept at coordinating rapid, well-learned movements. For example, when you are first learning to play a musical scale on the piano, your primary motor cortex directs the movement of your fingers on the piano keyboard. After you have learned the scale, however, control shifts to the cerebellum. In fact, the cerebellum appears to take over control of all well-learned movements, allowing the individual to perform the movements subconsciously, without involvement of the cerebrum. Often, when I drive to work in the morning, I get into my car, put the car in gear, and suddenly find myself pulling into the parking lot at the university. I don't remember anything about the drive: I don't remember stopping for red lights or passing any landmarks. That's because I used my cerebellum to drive while I used my cerebrum to think about upcoming events of the day.

The Basal Ganglia

The basal ganglia play an important role in relaying information to and from the cerebral cortex, although the specific functions of the basal ganglia with respect to movement are unclear (Bostan & Strick, 2010; Schmidt & Kretschmer, 1997). Recall from Chapter 4 that the basal ganglia are actually a group of nuclei, or clusters of neuronal cell bodies, located beneath the cerebral cortex. Information comes into the basal ganglia from the cerebral cortex, is processed there, and then is sent back to the cerebral cortex. At least five independent pathways have been identified in the basal ganglia (Weiner & Lang, 1995). For example, one circuit receives information from the somatosensory cortex. Another circuit gets input from association areas in the cerebral cortex and relays that input to the prefrontal cortex. Researchers believe that the most important function of the basal ganglia is to inhibit specific regions of the cerebral cortex associated with movement to stop movements before they begin (Folstein, 1989).

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Everett Collection/SuperStock

Photo 5.6 Lou Gehrig's disease is named after baseball player Lou Gehrig, who was forced to retire due to his illness.

5.4 Movement Disorders Damage to muscles, motor neurons, the spinal cord, the pyramidal system, or the extrapyramidal system can cause a movement disorder. Let's look at the types of disorders associated with damage to each of these structures or systems.

Damage to Muscles

Skeletal muscles must be intact and healthy in order to function properly. For example, when a muscle is separated from the skeleton, as happens with a torn tendon, contraction of the muscle does not produce the expected movement. Another disorder, muscular dystrophy, causes wasting of the muscle fibers, which weakens muscular contraction. There are several forms of muscular dystrophy, each of which is most prevalent in certain age groups. However, all forms of this disorder appear to have a genetic basis, and all result in progressive muscle weakness and physical disability. A cure for muscular dystrophy appears to be right around the corner. Scientists have discovered a way to block the genetic error that causes muscular dystrophy, and drugs are under development to produce this blockage in people who inherit the flawed gene (Nakamori & Thornton, 2011; Wheeler et al., 2009). Myasthenia gravis is a movement disorder associated with the progressive degeneration of acetylcholine receptors located at neuromuscular junctions. It is an autoimmune disease in which antibodies attack and destroy acetylcholine receptors on skeletal muscles, leaving the afflicted individual with muscle weakness and rapidly fatiguing muscle contractions. This disorder occurs most often in women between the ages of 20 and 30, although men are more likely than women to develop the disorder after the age of 40. Although no cure for myasthenia gravis presently exists, the disorder can be treated with drugs that increase the amount of acetylcholine that is available at the synapse to stimulate the remaining neuromuscular receptor sites. A blood-filtering process, known as plasmapheresis, is also used to remove the muscle-attacking antibodies from the blood (Lambert, 2012; Spring & Spies, 2001).

Damage to Motor Neurons

Motor neurons, as you learned earlier in this chapter, are the final common path leading to muscles. Damage to motor neurons would most certainly affect movement adversely. One disorder, known as amyotrophic lateral sclerosis (ALS), is caused by the degeneration of motor neurons in the spinal cord and brain. (This disorder, which typically first appears in middle or late adulthood, is also referred to as Lou Gehrig's disease, named after the famous baseball player who was stricken with it.) As more and more motor neurons die, the symptoms of ALS progress from muscle weakness to muscle wasting and extreme impairment of movement. Abnormal, excessive glutamate activity is thought to produce the motor neuron degeneration seen in ALS. Currently, no treatment or cure is available for individuals with ALS (Cheah et al., 2010).

Damage to the Spinal Cord

Spinal cord injuries can produce a range of disorders, depending on the location of the injury. Damage to the cervical spinal cord is a common injury that occurs in diving, skiing, and automobile accidents. Crushing or tearing of the cervical spinal cord typically results in quadriplegia. As its name implies, quadriplegia involves paralysis, or loss of motor function, of all four limbs (quattuor means "four" in Latin).

Often, damage to the cervical spinal cord does not result in total loss of movement in the arms and hands. Recall from Chapter 4 that innervation for most muscles is typically spread over several segments of the spinal cord. For example, the motor neurons that control muscles in the arms and hands are scattered over segments C5, T2, and T3. Damage to the spinal cord at C6, for example, would impair biceps muscle fibers that receive innervation from motor neurons in T2 and T3. However, those muscle fibers in the biceps that receive innervation from motor neurons in C5 would be spared, and weak control of the biceps muscle would be observed with a C6 injury.

Damage to the thoracic or lumbar area of the spinal cord usually produces paraplegia. In paraplegia the hind limbs lose their motor function. The forelimbs, or arms, escape impairment in paraplegia because the cervical spinal cord is not injured and remains intact. However, damage to the thoracic or lumbar area interrupts communication between the brain and the motor neurons that control muscles in the legs and feet. Thus, voluntary movement of the legs and feet is impaired.

Most spinal cord injuries do not involve complete breaks of the spinal cord. In most cases only partial damage occurs. People with partial damage to the spinal cord are often ambulatory, or able to walk, with or without assistance (Domingo et al., 2012). Keep in mind that sensory axons enter the spinal cord on the dorsal side. Thus, damage to the spinal cord can produce sensory, as well as motor, impairment.

Whenever damage to the spinal cord occurs, spinal shock, a condition in which no reflexes can be elicited, is observed immediately following the injury. Spinal shock can last for hours, days, or weeks following the injury and involves a total loss of spinal reflex activity. As you learned earlier in this chapter, spinal reflexes remain intact following surgical severance of the spinal cord. However, immediately following damage to the spinal cord, no reflexes can be elicited. It appears that the spinal cord goes into a state of shock following disconnection from the brain.

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In rats, dogs, and cats, spinal reflexes return within a few hours or days of the spinal injury, although the animal remains paralyzed and cannot engage in voluntary movement. Unfortunately, for monkeys, apes, and humans, recovery from spinal shock does not typically occur (Creed, Denny- Brown, Eccles, Liddell, & Sherrington, 1932). Following injury to the spinal cord, primates do not recover spinal reflexes as fully as lower animals do. Even the withdrawal reflex cannot ordinarily be elicited. In humans the urination and defecation reflexes shut down immediately following spinal cord injury, and the injured patients require urinary catheterization (a tube placed into the bladder to remove urine) and special assistance in bowel function to maintain elimination of wastes. It appears that motor neurons in the spinal cords of primates rely profoundly on innervation from the brain. When this innervation is interrupted because of damage to the spinal cord, the motor neurons cannot function normally, and reflexive action is disrupted.

Damage to the Pyramidal System

Damage to any part of the pyramidal system will affect movement, especially fine motor control. The primary motor cortex, which is located at the top of the brain directly under the skull, is particularly vulnerable to damage from trauma, such as a blow to the head. Discrete damage to the primary motor cortex will affect only a small set of muscles. For example, a small tumor on the most superior aspect of the primary motor cortex will impair walking or foot movement, whereas a tumor on the inferior aspect of the primary motor cortex will affect jaw movement. Recent research has demonstrated that the primary motor cortex is more flexible than originally believed. When one area of the primary motor cortex is damaged, other areas of the primary motor cortex can take over the function of the damaged area.

Damage to any part of the corticospinal tract results in transient flaccid paralysis. Let's take the term transient flaccid paralysis apart. You know what paralysis is: an inability to move voluntarily. The word transient refers to the fact that this paralysis is temporary, and the word flaccid means that there is a loss of muscle tone. Damage to the pyramidal system results in a temporary state of paralysis in which the patient has no muscle tone. The limbs feel like limp noodles when tested. If, following an automobile accident, a person comes into the emergency room on a stretcher and is paralyzed with a loss of muscle tone, you can be sure that the injured individual has suffered damage to the pyramidal motor system.

Transient flaccid paralysis usually lasts for only a few days or weeks following pyramidal damage. It is gradually replaced by a more permanent state of hyperreflexia, in which the injured individual has extremely reactive reflexes. For example, when a knee jerk reflex is tested immediately following pyramidal damage, no reflex is elicited. However, when tested for a knee jerk reflex several weeks following pyramidal injury, the patient will typically give an extremely strong extension response.

The primary motor cortex receives information from other areas of the cerebrum, including the prefrontal cortex, the parietal lobe, and the temporal lobe. Sometimes damage to these areas of the brain will have an adverse effect on the functioning of the primary motor cortex and on fine motor control. In one disorder, called apraxia, the individual cannot organize movements into a productive sequence (Benton, 2009). For example, when given an envelope and a sheet of paper, the person with apraxia cannot figure out how to fold the paper and put it into the envelope, even after being shown how to do it. The person with apraxia cannot complete a series of movements that must be carried out sequentially. The primary motor cortex is typically intact and undamaged in apraxia, but other areas of the cortex are impaired, particularly those areas of the parietal and prefrontal cortex in the left hemisphere that relay information to the primary motor cortex about the sequence of movements to be performed.

Damage to the Extrapyramidal System

Recall that many diverse brain structures comprise the extrapyramidal system. Damage to any of these structures produces impairment of the motor system. In contrast to the pyramidal system, damage to the extrapyramidal motor system does not produce transient flaccid paralysis. Instead, immediately following extrapyramidal damage, hyperreflexia and spasticity are observed in the injured person. Spasticity interferes with normal smooth movement of the limbs. As the injured person attempts to move a limb, the limb moves in a jerky fashion until rigidity sets in, halting movement altogether.

Let me give you an example. Consider the knee jerk reflex. Let's take a person with extrapyramidal damage and test the knee jerk reflex. Tapping the tendon beneath the kneecap stretches the extensor (or quadriceps) muscle in the leg, as you've already learned. When this tendon is tapped, stretch receptors in the extensor muscle initiate a vigorous contraction of that muscle, and the leg extends. However, when the extensor muscle contracts vigorously, it violently stretches the flexor muscle of the leg. In a person with extrapyramidal damage, the stretch reflex in the flexor muscle occurs forcefully, flexing the leg and powerfully stretching the extensor muscle. Stretching the extensor muscle sets off the stretch reflex in the extensor muscle once again, causing extreme contraction of the extensor muscle and stretching of the flexor muscle.

Damage to the Basal Ganglia

Damage to particular extrapyramidal structures produces specific movement disorders. For example, damage to the basal ganglia causes a number of problems, including tics and choreas. Tics are brief, involuntary contractions of skeletal muscles produced by the basal ganglia (Bronfeld, Belelovsky, & Bar-Gad, 2011). Usually these tics are confined to the head and neck and typically consist of a twitch in one or more facial or shoulder muscles. Choreas involve more elaborate involuntary movements of the head, arms, and legs. Hemiballismis is a form of chorea that includes uncontrolled flailing of the arms and legs.

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Biophoto Associates/Science Source

Photo 5.7 The ventricles are enlarged, and the basal ganglia and cerebral cortex are much reduced in the brain of an individual with Huntington's disease (right), compared to the normal brain (left).

These uncontrolled movements, especially choreas and hemiballismus, are observed in some individuals with cerebral palsy. Cerebral palsy is a movement disorder that is caused by damage to the motor areas of the cerebrum, including the motor cortex and basal ganglia (Hiyane et al., 2012). Although the cause of most cases of cerebral palsy is unknown, it can develop in infants before birth or shortly after birth (Collins, Lorenz, Jetton, & Paneth, 2001; Schendel, 2001; Shatrov et al., 2010). Many different forms of cerebral palsy exist, depending on the extent and location of cerebral damage. Damage to the basal ganglia in cerebral palsy can result in spasticity, disturbed control of balance, and uncontrolled movements.

Huntington's Disease

Perhaps the best-known chorea is the disorder known as Huntington's chorea or Huntington's disease, which we discussed in Chapter 1. Functioning of the basal ganglia becomes disrupted in Huntington's disease, producing tics and uncontrollable muscle contractions early in the disease and culminating in dementia and psychosis in the end stages of the illness. Research has demonstrated that Huntington's disease is linked to a dominant gene on chromosome 4, which increases dopamine activity in the basal ganglia (Fischer, 1997; Nicholson & Faull, 1996; Redgrave et al., 2010; Trottier & Mandel, 2001).

This image illustrates the brain atrophy, or destruction of tissue, that is seen in Huntington's disease.

No known cure exists for Huntington's disease at present. In the early stages of the illness, antipsychotic medication, which reduces the activity of dopamine in the brain, is used to treat the involuntary muscle contractions. However, no treatment helps much in the end stages of the illness. If glutamate overactivity is responsible for the degeneration of neurons in the basal ganglia, drugs that treat epilepsy by decreasing glutamate activity or increasing GABA activity might prove useful for treating and even preventing Huntington's disease (Gajcy, Lochynski, & Librowski, 2010).

Parkinson's Disease

Another well-known illness associated with damage to the basal ganglia is Parkinson's disease. Parkinson's disease appears to be caused by destruction of dopamine-producing cells in the substantia nigra in the basal ganglia, resulting in a depletion of dopamine in the basal ganglia. (In 2000 Arvid Carlsson received the Nobel Prize in physiology for his research on dopamine and its role in Parkinson's disease.) As dopamine levels decline, movement becomes impaired in Parkinson's disease. The first motor symptoms include tremor, especially of the hands, and unsteadiness and loss of balance, which leads to falls. Rigidity and inability to complete a movement occur later in the course of the illness. Parkinson's disease is a progressive illness that ultimately leaves persons unable to care for themselves. Because dopamine levels in the brain are diminished in Parkinson's disease, psychological depression is often a component of the disorder that must be treated.

Parkinson's disease is most frequently seen in the elderly, although individuals in their 30s or 40s (or, in rare cases, even younger) may be diagnosed with this disorder. In addition, men are more likely to develop this disorder than are women. Actor Michael J. Fox was first diagnosed with Parkinson's disease at age 30, whereas Pope John Paul II and former U.S. attorney general Janet Reno developed Parkinson's later in life.

The exact cause of Parkinson's disease is unknown. That is, no one can explain how or why dopamine-producing cells in the substantia nigra are destroyed. However, studies of young people in California who inadvertently injected themselves with a bad batch of synthetic heroin that contained a lethal by-product, called methyl-phenyl-tetrahydropyridene or MPTP, gave investigators a clue as to how Parkinson's disease develops. These young drug users developed dramatic cases of Parkinson's disease after using the MPTP-contaminated drug repeatedly for several days. Several of the afflicted people became so immobile that they could move only their eyes. Following the discovery of the effects of MPTP in humans, investigators at the National Institute of Mental Health tried to produce the same results in monkeys. They found that injections of MPTP into monkeys produced full- blown Parkinson's disease in those animals (Burns et al., 1983). Postmortem examination of the monkeys' brains revealed destruction of the substantia nigra following injection of MPTP.

Scientists have demonstrated that a widely used pesticide, rotenone, produces Parkinson's-like symptoms in rats (Betarbet et al., 2000; Jackson- Lewis, Blesa, & Przedborski, 2012). Rotenone is structurally similar to MPTP and is found in hundreds of products, including flea and tick powders and plant pesticides. Recently, a number of international research teams have reported an association between Parkinson's disease and exposure to pesticides in humans (Parrón, Requena, Hernández, & Alarcón, 2011; Spivey, 2011; Wang et al., 2011; Wirdefeldt, Adami, Cole, Trichopoulos, & Mandel, 2011).

Classical antipsychotic drugs, which decrease dopamine activity in the brain, produce symptoms that resemble Parkinson's disease. These symptoms are labeled extrapyramidal side effects and include tremors, muscular rigidity, and a shuffling gait. The extrapyramidal side effects are believed to be the result of decreased dopamine activity and increased acetylcholine activity in the nervous system. Drugs that decrease acetylcholine activity, called anticholinergic medications, and drugs that increase dopamine activity, called dopaminergic medications, reduce extrapyramidal side effects (Stanilla & Simpson, 2001).

Treatment for Parkinson's Disease

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Investigators are still trying to find a cure or lasting treatment for Parkinson's disease. Because dopamine is depleted in the basal ganglia in Parkinson's disease, you would think that it would be an easy matter just to give the person a pill containing dopamine. Unfortunately, dopamine cannot cross the blood-brain barrier, so a dopamine pill won't work. But a precursor of dopamine, a substance that is readily converted to dopamine in the brain, can cross the blood-brain barrier. This precursor is called levo-dopa or L-dopa. L-dopa, when taken orally, enters the bloodstream, crosses the blood-brain barrier, and is converted into dopamine in the brain. This drug is especially helpful in the early stages of the illness. However, L-dopa has a number of unwelcome side effects, including uncontrolled, extraneous muscle contractions, increased blood pressure, occasional psychotic symptoms, and headaches (Symmonds et al., 2013). It cannot be used every day, on a long-term basis. Hence, researchers are looking for alternative treatments for Parkinson's disease.

A number of alternative treatments for Parkinson's disease appear promising. These treatments are especially useful when patients are receiving the maximal daily dose of L-dopa with no improvement in symptoms or when patients develop dyskinesias (movement problems, such as choreas) in response to L-dopa. Alternative drugs therapies, such as glutamate antagonists, are currently under investigation to determine their efficacy in treating Parkinson's disease. Glutamate hyperactivity has been implicated as an underlying cause of Parkinson's disease. Thus, reducing glutamate activity should decrease clinical manifestations of Parkinson's disease. Experiments with rats treated with antipsychotic drugs (which block dopamine activity, producing rigidity and immobility in rats) and with monkeys injected with MPTP demonstrate that glutamate antagonists can reduce Parkinsonian symptoms (Alarcon, Bradley, & McKendree-Smith, 2000; Morin et al., 2010; Ossowska, Lorenc- Koci, Konieczny, & Wolfarth, 1998; Papa & Chase, 1996; Starr, 1995).

Other treatments for Parkinson's disease are also under development, including stem cell therapy and deep brain stimulation. Stem cells are specialized cells in the body that are capable of dividing and transforming into different types of cells needed for the growth and repair of body tissues. Implanting stem cells that are capable of transforming into dopamine-producing neurons into the brains of individuals with Parkinson's disease has been demonstrated to be a successful treatment for many with Parkinson's (Cooper, Hallett, & Isacson, 2012). Likewise, stimulation of deep brain structures, such as the hypothalamus, substantia nigra, basal ganglia, and hippocampus, has been shown to reduce many of the devastating symptoms of Parkinson's disease, including tremors, postural problems, and cognitive difficulties (Starr et al., 2010; Uitti, 2012).

Damage to the Cerebellum

Damage to the cerebellum interferes with the ability of this brain structure to coordinate movement. Depending on the extent of the damage, movement impairments can vary. For example, tumors in the cerebellum produce a variety of problems related to the location of the tumor. Tumors in the posterior cerebellum disrupt communication with the vestibular system and interfere with balance, whereas tumors that affect midline cerebellar structures disturb bilateral coordination of the limbs and trunk (Bastian et al., 1998).

People with cerebellar damage show a number of problems, including ataxia, which is an inability to walk or move in a coordinated fashion, and disequilibrium, a loss of balance. Staggering or a foot-dragging gait is evidence of cerebellar damage. Other individuals may be unable to perform rapid, well-learned movements following damage to the cerebellum. Instead, their movements become hesitant and slow.

As you know, the cerebellum is extremely dependent upon the senses as it coordinates movement. For example, as I walk across a room, the cerebellum receives information from my eyes about the presence and location of objects in the room, allowing me to cross the room without tripping over shoes and other items on the floor. In Chapter 6 we will examine the various sensory systems, and we will look at a number of sensory disorders that can disrupt cerebellar function.

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5.5 Chapter Summary Muscle Structure and Function

Each muscle cell is called a muscle fiber, which contains contractile tissue.

Each muscle fiber has a chemically sensitive endplate that contains receptors for acetylcholine. Acetylcholine stimulates contraction of the muscle fibers in skeletal, smooth, and cardiac muscle.

The synapse between the axon of a motor neuron and the endplate of a muscle fiber is called a neuromuscular junction.

Different Muscle Types

Skeletal muscles are attached to the bones of the skeleton and produce flexion and extension movements of the limbs.

Smooth muscles are found in the walls of blood vessels and many internal organs, as well as in the skin and glands.

Skeletal Muscle Function

Flexion of a limb refers to a movement that bends the limb, whereas extension is a straightening of the limb.

Muscles that produce opposite movements around a joint are called antagonists.

Isotonic contraction occurs when a muscle shortens in length, pulling the attached bones in the direction of the contraction. During isometric contraction, the muscle does not shorten but rather remains the same length, with an increase in muscle tone.

Spinal Control of Movement

The spinal cord mediates rapid, automatic responses to stimuli, called reflexes.

A large number of reflexes are organized in the spinal cord, including the stretch reflex, tendon reflex, withdrawal reflex, crossed extensor reflex, elimination reflexes, and sexual reflexes.

The withdrawal, or flexion, reflex involves an immediate withdrawal movement that occurs in response to a painful stimulus.

In the crossed extensor reflex, one leg extends when the other flexes to withdraw from a painful stimulus.

Urination and defecation involve a stretch reflex.

Control of Movement by the Brain

The brain controls movement by means of the pyramidal motor system and the extrapyramidal motor system.

Arising from the primary motor cortex, the pyramidal system traverses the spinal cord through the corticospinal tract. Axons leaving the primary motor cortex pass without synapsing to target motor neurons in the ventral horn of the spinal cord.

The extrapyramidal system arises from the cerebral cortex, the basal ganglia, the cerebellum, and the reticular formation. The function of the cerebellum is to coordinate well-learned movements and movements made in response to sensory stimuli. The basal ganglia are involved in relaying information to and from the cerebral cortex.

The pyramidal system develops later than the extrapyramidal system and regulates fine motor control, whereas the extrapyramidal system controls gross postural adjustments and other movements produced by large muscles.

Movement Disorders

Damage to muscles, motor neurons, the spinal cord, the pyramidal system, or the extrapyramidal system can result in a movement disorder.

Damage to Muscles

Muscular dystrophy and myasthenia gravis are associated with progressive damage to muscle fibers.

Damage to Motor Neurons

Amyotrophic lateral sclerosis (ALS) is caused by damage to motor neurons.

Damage to the Spinal Cord

Damage to the cervical spinal cord typically results in quadriplegia, whereas damage to the thoracic or lumbar spinal cord causes paraplegia.

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Damage to the Pyramidal System

Damage to the pyramidal system results in transient flaccid paralysis, which eventually is replaced by hyperreflexia.

Apraxia is also associated with damage to the pyramidal motor system.

Damage to the Extrapyramidal System

Damage to the extrapyramidal system immediately produces hyperreflexia and spasticity.

Damage to the Basal Ganglia

Damage to the basal ganglia can produce tics, choreas as seen in Huntington's disease, and Parkinson's disease.

Parkinson's disease is caused by destruction of dopamine-producing cells in the substantia nigra. Treatments for Parkinson's disease include drug therapy, involving L-dopa and glutamate antagonists, and surgical treatments.

Damage to the Cerebellum

Damage to the cerebellum can result in ataxia, disequilibrium, and disruption of rapid, well-learned movements.

Questions for Thought

1. Why do some reflexes emerge later than others during development?

2. Give an example of how you use isometric muscle contraction every day. Give an example of isotonic contraction.

3. If you had a brain tumor at the superior aspect of your primary motor cortex, movement to which parts of your body might be affected?

4. Explain how the stretch receptors in the muscle spindles and Golgi tendon organs regulate muscle tone.

5. Name three differences between the pyramidal and extrapyramidal motor systems.

6. What are the effects of spinal shock?

Chapter 5 Flashcards

Web Links

To learn more about infant reflexes and development, visit the MedlinePlus website. Here you will see a general overview of each kind of reflex, descriptions of those that carry on into adulthood, and any abnormalities that may occur in development. http://www.nlm.nih.gov/medlineplus/ (http://www.nlm.nih.gov/medlineplus/)

For information on Huntington's disease, Parkinson's disease, and other types of movement disorders, visit the Mayo Clinic's website. This page offers detailed information on symptoms, causes, treatment, and drugs that help those suffering from movement disorders. http://MayoClinic.com/health-information (http://MayoClinic.com/health-information)

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Key Terms

Click on each key term to see the definition.

amyotrophic lateral sclerosis (ALS) (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A progressive disorder caused by degeneration of motor neurons in the spinal cord and brain.

apraxia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder caused by cerebral damage in which a person cannot organize movements into a productive sequence and can no longer perform previously familiar movements with the hands.

ataxia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

An inability to walk in a coordinated fashion.

atrophy (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A deterioration of tissue.

Babinski reflex (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A reflex in infants when a touch to the ball of the foot causes the toes to fan (positive) or when a touch to the ball of the foot causes the toes to curl (negative).

cerebellar cortex (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The cerebellum's outermost layer, which contains Purkinje, Golgi, stellate, basket, and granule cells.

cerebral palsy (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A motor disorder caused by damage to the developing brain.

choreas (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Involuntary contractions that produce movements of the head, arms, and legs.

corticospinal tract (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A group of axons that carries messages from the primary motor cortex to motor neurons in the spinal cord.

crossed extensor reflex (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A spinal reflex that typically occurs in conjunction with another reflex, the withdrawal reflex; it consists of withdrawing an affected body part from something that is causing pain.

disequilibrium (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A loss of balance due to impairment of the cerebellum.

extension (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A movement that straightens a limb.

extrapyramidal motor system (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

10/14/20, 7)30 AMPrint

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The motor system that coordinates gross postural adjustments and arises from the cerebral cortex, basal ganglia, cerebellum, and reticular formation.

flexion (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A movement that bends a limb.

Golgi tendon organ (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A stretch receptor that provides feedback to the nervous system about muscle contractions.

Huntington's disease (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A genetic disorder linked to chromosome 4, which increases dopamine activity in the basal ganglia, producing tics and uncontrollable muscle contractions.

L-dopa (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A drug used to treat Parkinson's disease that crosses the blood-brain barrier and is converted to dopamine in the brain.

muscle fiber (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A muscle cell; it contains a nucleus, mitochondria, and other typical cellular components.

muscle spindle (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A special structure interspersed among the muscle fibers in skeletal muscles; it is composed of several short muscle fibers that are joined to a centralized structure called a nuclear bag.

muscular dystrophy (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder characterized by wasting of the muscle fibers, which causes muscular weakness.

myasthenia gravis (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder characterized by progressive loss of acetylcholine receptors in the neuromuscular junction.

neuromuscular junction (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The junction between the axon terminal button and the muscle fiber.

paraplegia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder involving loss of motor function to the lower limbs.

Parkinson's disease (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A movement disorder caused by destruction of dopamine-producing cells in the substantia nigra, with symptoms of tremor, loss of balance, and rigidity of limbs.

polysynaptic reflexes (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Reflexes that involve more than one synapse.

primary motor cortex (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The source of the pyramidal motor system that sends impulses involving fine motor control to motor neurons.

pyramidal motor system

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(http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The motor system that arises from the primary motor cortex in the frontal lobe and directs fine motor control of skeletal muscles.

quadriplegia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disability involving impairment of motor and sensory functions in all four limbs.

reflexes (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Rapid, automatic sets of muscle contractions made in response to a particular stimulus.

skeletal muscle (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Muscle that is controlled by the somatic nervous system and is attached to bones of the skeleton.

smooth muscles (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Muscles that are controlled by the autonomic nervous system and are found in the walls of blood vessels and in the walls of many organs and glands.

spasticity (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder that is characterized by disturbed control of balance and uncontrolled movements.

spinal shock (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A condition seen immediately following damage to the spinal cord in which no spinal reflexes can be elicited.

stretch reflex (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Contraction of a muscle in response to stretching of the annulospiral receptors in that muscle.

tics (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Brief, involuntary contractions of specific skeletal muscles produced by damage to the basal ganglia.

transient flaccid paralysis (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A complete loss of muscle tone, with paralysis, seen immediately after damage to the pyramidal motor system.

unisynaptic reflex (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A reflex that involves only one synapse.

withdrawal reflex (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The flexion of a limb in response to a painful or noxious stimulus.

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Consciousness and Sleep 8

© Heide Benser/Corbis

Learning Objectives

After completing this chapter, you should be able to:

List Delacour's criteria for consciousness and give a real-life example of each.

Differentiate between being in a coma, being in a vegetative state, and having locked-in syndrome.

Summarize the results of Sperry's research with split-brain patients.

Explain how electroencephalography has contributed to our knowledge of sleep and consciousness.

Draw the four main types of brain waves associated with sleep and consciousness.

Identify the components of a sleep cycle.

Describe the roles that structures in the hindbrain, hypothalamus, and thalamus play in the production of sleep and consciousness.

Describe the evidence for evolutionary theory of sleep.

Explain the activation-synthesis hypothesis of dreams.

Identify at least six sleep disorders.

Explain the difference between advanced-sleep-phase syndrome and delayed-sleep-phase syndrome.

Priscilla is a 20-year-old college student with a history of sleepwalking. In fact, Priscilla has been sleepwalking since she was 3 or 4 years old. A

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junior in college, she shares an apartment with two other women; each has her own bedroom. Nearly every night, Priscilla wakens one or both of her roommates with her sleepwalking "antics." Often, Priscilla sleepwalks into their rooms while they are sleeping and wakens them to tell them some bit of nonsense, such as, "I'm locked out of the house, and I can't get back in." Other nights, her roommates are awakened because of the noise she makes in the apartment while sleepwalking. For example, one night she pulled down the draperies in the living room as she tried to climb them in her sleep.

Before her junior year in college, Priscilla had a different roommate every semester because her constant sleepwalking scared them away. One roommate left before the end of the semester after Priscilla wakened her one night, standing naked before her bed, and announced in French, "I am a man."

Sleepwalking is a state in which a person appears to be conscious but is actually asleep. But what does it mean to be conscious? In this chapter we will examine the states of consciousness and sleep. We will also examine those in-between states, such as sleepwalking, dreaming, and coma, in our attempt to understand what consciousness is and how it occurs.

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8.1 Consciousness Consciousness is difficult to define. It refers to an awareness of one's self and one's surroundings. But consciousness seems to be more than that. Some investigators believe that consciousness requires a state of wakefulness, although others consider dreaming to be a state of consciousness. Obviously, there is no consensus about the nature of consciousness (Augustenborg, 2010; Damasio, 1999). Early psychologists studied consciousness by examining metacognition, or people's awareness of their own mental processes (Nelson, 1996). In a typical experiment, people were exposed to specific stimuli and then asked to make reports about their introspections, or thought processes, concerning these stimuli. These early studies were loaded with methodological problems and really didn't tell us much about important aspects of consciousness, such as alertness and attention.

Jean Delacour (1995) has suggested that consciousness is characterized by six main features:

1. behavior that is coherent and controlled;

2. detection of novel stimuli and orienting responses to those stimuli;

3. behavior that is goal directed and flexible;

4. production and comprehension of language;

5. evidence of memory for facts and events in one's life; and

6. presence of metacognition.

According to Delacour's six criteria for consciousness, the behaviors exhibited while a person is sleepwalking are not considered conscious because these behaviors are neither coherent nor goal directed. Metacognition is absent during sleepwalking, too. That is, a person is not aware of his or her own thought processes while sleepwalking.

A close examination of Delacour's criteria reveals that consciousness appears to involve structures in the frontal lobe, particularly the prefrontal cortex. Keep in mind that, while awake, you perform many activities unconsciously. On many days I back my car out of my driveway as I prepare to drive to work, and the next thing I know, I'm pulling into the parking lot outside my office building, with no conscious recollection whatsoever of driving to work, stopping at traffic signals, and so forth. Somehow, although awake, I got to my office unconsciously, with no awareness of the actions that I performed to reach my destination.

Thus, consciousness appears to be more than merely being awake. Behaviors that are performed automatically do not require conscious processing. In contrast, unexpected events and novel, complex tasks are processed consciously. You might have noticed that, when you consciously attend to a well-learned automatic behavior such as climbing the stairs, your performance of that behavior is slowed down and less accurate. The next time you walk up a flight of stairs, try to pay attention to every movement of your legs. You will find that your movements become awkward when you switch the performance of automatic behaviors from unconscious to conscious processing.

Disorders of Consciousness

To obtain a better understanding of consciousness, let's consider a number of disorders, such as amnesia, frontal lobe syndrome, and autism, which are characterized by impairment of consciousness. In this section we will also examine two disorders, coma and locked-in syndrome, whose primary symptoms include disturbance of consciousness. Dissociative states will also be discussed because these states represent a disruption of consciousness.

Amnesia

The most common form of memory disorder is amnesia, which is a loss of memory. According to Delacour's criteria for consciousness, accessing memory is necessary for conscious processing to occur. This means that any impairment of memory interferes with conscious processing.

Two forms of amnesia, called anterograde amnesia and retrograde amnesia, are caused by damage to the hippocampus. In Chapter 4 you learned that the hippocampus is responsible for the creation of permanent, or long-term, memory. The extent of hippocampal damage will influence the type of amnesia produced. A person with retrograde amnesia will not remember events that occurred before the time of brain injury. Some people have loss of memory for a few hours, a few days, or even a few years before the brain injury. Damage to a limited area of the hippocampus is associated with shorter periods of memory loss.

Anterograde amnesia is an inability to form new memories that results from damage to the hippocampus on both sides of the brain. One well- studied case is a patient known as H. M., who developed anterograde amnesia following surgical removal of the hippocampus on both sides of his brain. Although he could recall memories from his youth, H. M. could not remember anything that happened to him since his surgery (James & MacKay, 2001; Milner, 1966; Sagar, Cohen, Corkin, & Growdon, 1985; Spiers, Maguire, & Burgess, 2001; Squire & Wixted, 2011). He continually lost his way around the hospital following his surgery, and, when his parents moved to a new home, he could not remember how to get to their new

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Erin Paul Donovan/SuperStock

Photo 8.1 Phineas Gage's accident is commemor-ated in a bronze plaque in Cavendish, Vermont.

Fotosear ch/SuperStock

Photo 8.2 Autistic individuals cannot easily shift their attention

house.

Another type of amnesia is psychogenic amnesia, which is caused by stress or psychological trauma. Individuals with psychogenic amnesia cannot retrieve information stored in long-term memory. People with psychogenic amnesia often are found roaming around with no memory of their identity or any information about their pasts.

Frontal Lobe Syndrome

Injury to the frontal lobe produces impairments of attention, metacognition, goal-directed behavior, and other aspects of working memory required for conscious behavior. One of the most striking features of frontal lobe syndrome is goal neglect, in which the affected individual disregards instructions and ignores requirements of a task, although the individual is able to explain the instructions or rules for task completion (Duncan, 1995). Except for goal neglect, impairment of conscious processes is minimal in patients with frontal lobe syndrome. The "Case Study" describes a famous case of frontal lobe syndrome.

Case Study: The Story of Phineas Gage

Phineas Gage was a highly intelligent, hardworking man who was well liked by his coworkers before he suffered a tragic accident in 1848. At the time of his accident, he was 25 years old and a foreman for a construction crew that was laying railroad tracks in Vermont. To lay tracks in the mountainous, rocky terrain of Vermont, the crew had to use blasting powder to break up big rocks that were in the path of the tracks. Normally, the men would drill a hole in a rock, pour blasting powder into the hole, put a fuse on top, and then cover the powder and fuse with sand. A long metal rod was then used to tamp or pack the sand down before the fuse was lit.

One day, however, Gage was distracted for a moment and began tamping down the blasting powder before the sand was added. The

impact of the tamping rod on the blasting powder ignited a huge explosion, causing the rod to shoot up and rip through Gage's head. The rod, which was about 42 inches long and more than 1 inch in diameter, entered just below his left cheekbone, destroying his left eye, and exited through the top of his head. Miraculously, Gage survived this terrible accident. He stood up immediately after the impact knocked him off his feet, began talking normally, and was able to walk away with his men.

Within a few months, Gage had recovered well enough to return to work. He had lost his left eye, but his speech, memory, and intelligence were unaffected by the accident. However, his personality had changed dramatically. Formerly a polite, socially responsible man, he became extremely rude, and he began to curse routinely, lie to his coworkers, and show up for work irregularly. He seemed to have lost all sense of social awareness and was eventually fired from his job. After losing his job, he wandered around the United States and South America until his death in 1861 in San Francisco, where he was buried without an autopsy.

Five years after Gage's death, the country doctor who had treated him asked Gage's family to have the body exhumed so that he could examine Gage's skull. Gage's doctor later sent the skull and the tamping rod to Harvard University, where they are currently exhibited at the Warren Anatomical Medical Museum.

Autism

Autism is a cognitive disorder in which consciousness is impaired. For example, autistic individuals cannot easily shift their attention from a stimulus that preoccupies them to another stimulus. Thus, an autistic individual might not respond to a stimulus that most of us would find important, like a human voice. Other evidence of impaired consciousness in autistic people includes behaviors that are not coherent, flexible, and goal oriented and an absence or near absence of language. Asperger's syndrome is a form of autism in which the affected individuals are high functioning, displaying excellent language skills and evidence of metacognition (Jackson, Skirrow, & Hare, 2012). People with Asperger's syndrome can describe their inner feelings and report their thoughts; thus, they

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from a stimulus that preoccupies them to another stimulus.possess a consciousness that is less impaired than that normally found in autism.

Coma

Coma is defined as a state of unconsciousness in which the eyes are closed. This is a very broad, nonspecific definition because many different levels of awareness are observed in coma. The Glasgow Coma Scale (Teasdale & Jennett, 1974) is used to assess the level of functioning in an individual in a coma state. Table 8.1 describes the various stages of the Glasgow Coma Scale. To obtain a Glasgow Scale score, the clinician must assess eye opening, motor response, and verbal response of the comatose patient. In general, a low score on the scale is associated with a poor prognosis for recovery (Masson et al., 2001). Approximately 45% of people who have a Glasgow Coma Scale score of less than 5 will die before waking from the coma, whereas only 3% of people with a score greater than 12 will die. Some people who do survive enter a permanent vegetative state in which their eyes are open but their behaviors are reflexive and primitive. For example, individuals in a permanent vegetative state will often cry when they are distressed or in pain. (Crying is a primitive response.) Speech is never observed in a person in a permanent vegetative state.

Table 8.1: The Glasgow Coma Scale

Eye opening

E Score Clinical Signs

4 Opens eyes spontaneously

3 Opens eyes on command

2 Opens eyes when pinched

1 Does not open eyes to pain

Motor response

M Score Clinical Signs

6 Follows simple commands

5 Withdraws body part when pinched

4 Pulls away from examiner's hand when pain applied

3 Flexes body inappropriately to pain

2 Body becomes rigid in response to pain

1 Has no response to a pinch

Verbal response

V Score Clinical Signs

5 Carries on normal conversation, oriented for time and place

4 Talks to examiner but makes no sense

3 Seems confused or disoriented

2 Makes sounds that examiner doesn't understand

1 Makes no noise

Coma Score: (E + M + V) = 3 to 15

Source: Teasdale, G., Jennett, B. (1974). Assessment of coma and impaired consciousness: A practical scale. Lancet, 2(7872), 81–84.

Coma results from brain damage caused by trauma, anoxia (oxygen deprivation), or disease. For example, coma is often associated with head injuries received in car accidents. Typically, in a car accident, when the car slams to a halt, people inside are first pitched forward, as their bodies

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continue in the forward motion of the car, and then are tossed backward due to the force of inertia. This means that injuries occur in the front of the brain (or frontal lobes) as a person's body is propelled forward in space after the impact, and injuries also occur in the back of the brain (parietal and occipital lobes) when the body is jerked backward in space. In general, damage that is limited to one hemisphere does not produce a coma state. That is, both hemispheres must be injured to induce coma. Other areas implicated in coma include the midbrain and reticular formation.

Locked-In Syndrome

This rare disorder occurs in individuals whose motor systems become permanently detached from conscious control. People with locked-in syndrome appear to be unconscious and in a coma because their eyes are closed and they do not move or respond to stimuli. However, these individuals are fully conscious and aware of their surroundings. Sometimes an individual with locked-in syndrome is able to move an eyelid and can communicate by means of blinking (such as, one blink means "yes," and two blinks mean "no"). Using eye blinks, a journalist named Jean- Dominique Bauby was able to dictate a whole book, The Diving Bell and the Butterfly, an amazing account of his life following a stroke that left him impaired with locked-in syndrome. Locked-in syndrome is usually associated with damage to the hindbrain, particularly in the area of the pons.

Dissociative States

In this chapter you've learned that one of the most prominent characteristics of consciousness is the integration of all sensory and memory components of the conscious experience, which results in a unified consciousness. In dissociative states, this integration becomes disrupted, and affected individuals can experience altered sensory perceptions, amnesia, attentional disorders, and distortion of time perception and identity (Bob & Svetlak, 2011; Krystal, Bennett, Bremner, Southwick, & Charney, 1995). For example, a person with dissociative symptoms may experience flashbacks, in which the emergence of vivid memories causes a past event to be experienced as happening all over again. Persons having a flashback may experience altered auditory and visual perceptions that cause them to feel as if they are reliving the past event. A disturbance in identity function can result in dissociative identity disorder, in which an individual can exhibit a number of different personae, some of whom are unaware of the existence of other personae, or in a fugue state, in which an affected person does not know his or her own identity and has no memory of the past (Spiegel et al., 2011).

Norepinephrine has been linked to flashbacks and other dissociative states (Krystal et al., 1995). For example, a drug that increases norepinephrine activity, called yohimbine, has been demonstrated to initiate flashbacks and panic attacks in individuals who have experienced a previous traumatic event. Three classes of drugs produce dissociative states in healthy people: (1) anesthetics that act as glutamate antagonists, like phencyclidine (PCP) and ketamine; (2) marijuana and related cannabinoids; and (3) hallucinogens that increase serotonin activity, such as LSD. These drugs all have the effect of altering sensory perceptions, distorting attention and memory, and causing a state of depersonalization, in which affected individuals feel as if they are outside of their own bodies.

Research on Consciousness

Research with brain-injured patients has contributed to our understanding of the biological bases of consciousness. For example, the wars in Afghanistan and Iraq have generated the largest percentage of service members sustaining traumatic brain injuries in history, and clinicians have reported a broad range of impairments in consciousness associated with these brain injuries (French & Parkinson, 2008; Lippa et al., 2010; Warden, 2006). Other research has examined consciousness in patients who have undergone brain surgery to correct a neurological problem or to remove a brain tumor.

In 1981 Roger Sperry, a professor at the California Institute of Technology, received a Nobel Prize for his research on cerebral function in individuals who had undergone a callosotomy, or surgical division of the corpus callosum. Recall from Chapter 4 that the corpus callosum is a thick band of axons that connects the two halves of the cerebrum (Figure 8.1). Severing the corpus callosum produces a permanent loss of communication between the two cerebral hemispheres and is performed only on patients with severely disabling seizure disorders who do not respond well to traditional drug treatment. These individuals are often referred to as split-brain patients after the surgery.

Figure 8.1: The corpus callosum In extreme circumstances, doctors will perform a callosotomy, a surgery that splits the corpus callosum. However, when the corpus callosum is split, the two cerebral hemispheres of the brain cannot communicate with one another.

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Immediately following callosotomy, split-brain patients appear disoriented and unable to coordinate their hand movements to work together. One man, for example, started to button his shirt with one hand, and the other hand immediately began unbuttoning the shirt! Because the left hand is controlled by the right side of the brain and the right hand by the left side, severing the corpus callosum leaves the postsurgical patient in a state where one hand does not know what the other hand is doing. However, within a month or so, the two cerebral hemispheres learn to work together, typically through the visual and auditory senses, which relay information to both halves of the cerebrum, and the postsurgical patient's behavior looks smooth and normal.

The participants in Roger Sperry's experiments were split-brain individuals who had undergone surgery several years prior to the experiments, and they looked essentially normal in their everyday behavior. However, the experiments conducted in Sperry's laboratory were able to demonstrate that something very unusual was taking place in these participants: They appeared to have a left-brain consciousness and a right-brain consciousness. When an object was placed in the left hand of one of Sperry's subjects (out of the subject's view; see Figure 8.2), the information was relayed to the right cerebral hemisphere only. (If the subject were able to see the object, information about that object would be sent to both sides of the cerebrum.) When asked to name the object in the left hand, these individuals could not identify the object because only the left hemisphere can produce language. However, when asked to pick out the object among a group of several objects behind a screen, the left hand could easily choose the correct object, and the right hand could not. The opposite was true for objects placed in the right hand: Split-brain subjects could name the object placed in their right hands and could select the correct object behind a screen, whereas they could not do the same thing with their left hands.

Figure 8.2: Sperry's split-brain studies In Figure A the man's left hemisphere did not see the word, so he could not name it. The right hemisphere, which did see the word, controls the left hand that writes "cat." In Figure B the feeling of the spoon in the left hand goes to the right hemisphere. The man cannot name the item and merely guesses. The left hemisphere produces language, but the left hemisphere has no knowledge of the spoon.

Sperry and his colleagues were surprised to discover that each hemisphere has a consciousness or awareness of its own (Gazzaniga, Bogen, & Sperry, 1962, 1992; Sperry, Gazzaniga, & Bogen, 1969). In split-brain patients, neither mind-right nor mind-left is aware of the other hemisphere's consciousness. That is, little, if any, cognitive or perceptual information is shared between the two cerebral hemispheres. However, a split-brain patient experiences a unitary consciousness, just like you and me, and is aware of only one mind and one set of sensory experiences and memories (Gazzaniga, 1989).

Further research with split-brain patients has demonstrated that this sense of unified conscious awareness is due to a special role of the left

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hemisphere in consciousness (Gazzaniga, 1989; Gazzaniga & LeDoux, 1978; Schechter, 2012). Because the left hemisphere contains the language centers necessary for the production of speech, carefully designed studies can give us a clear understanding of the function of the left hemisphere in consciousness. For example, in a test of concept association, when the right hemisphere of a split-brain patient was shown an image of a wintry, snow-covered scene, and the left hemisphere was shown an image of a chicken claw, the patient pointed to an image of a chicken with the right hand and pointed to an image of a shovel with the left hand. When asked why the chicken and the shovel were selected, the split-brain patient responded that chickens have claw feet and that the shovel was needed to clean out the chicken house. The left hemisphere did not have knowledge of the snow-covered scene, but it readily concocted an explanation for why the left hand selected a picture of a shovel (Gazzaniga, 1989). This experiment shows quite clearly that the left hemisphere is involved in interpreting incoming data based on the knowledge that it has.

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8.2 Sleep Studies of split-brain patients have provided us with a great deal of insight into the role of the cerebral hemispheres in the conscious processing of information. Research using EEG recordings of human brains during sleeping and waking states has helped us better understand the neural mechanisms underlying sleep and consciousness. Let's examine the findings of EEG research next.

Electrical Activity in Consciousness and Sleep

Electrical activity in the brain can be measured in two ways, as you learned in Chapter 1: through scalp electrodes pasted onto the skin overlying the skull and through intracranial electrodes inserted into the brain (intra- means "inside" and -cranial refers to the cranium or skull in Latin). The changes in electrical activity recorded by electrodes reflect the activity of hundreds or thousands of neurons lying directly beneath the electrode. Both types of recordings have revealed important information about brain activity underlying sleep and consciousness.

Research involving EEG measures recorded via scalp electrodes has revealed that brain activities associated with sleep and waking are quite different. In general, synchronized brain waves are the hallmark of deep sleep. Synchronized brain waves are large, slow, regular waves (Figure 8.3). In contrast, desynchronized brain waves, which are rapid, irregular brain waves, are observed during conscious states. States of high excitation or emotional states are associated with very fast and highly irregular EEG recordings. The fast, irregular brain waves associated with arousal are called beta waves. Beta waves occur at a frequency of approximately 13 to 50 waves per second and are associated with activation of the sympathetic nervous system. In addition, cognitive and emotional tasks that require intake of information, such as counting verbs in a written passage, checking for arithmetic errors, or looking at provocative slides, are associated with increased beta activity (Ray & Cole, 1985).

Figure 8.3: Four types of brain waves Can you explain the differences between these brain waves and what brain activities they are associated with?

On the other hand, alpha waves are observed during periods of relaxed wakefulness, when the parasympathetic nervous system is active. Alpha waves occur at a rate of 8 to 12 waves per second (Figure 8.3). Tasks that require attention to internal processing, such as performing mental arithmetic, creating sentences that begin with a particular letter, and mentally rotating geometric figures, are associated with increased alpha wave activity (Ray & Cole, 1985).

When alpha waves disappear and give way to slower brain waves, sleep occurs. Thus, sleep and wakefulness appear to be states along a continuum of brain activity levels, with wakefulness being associated with beta and alpha brain waves and sleep being associated with slower brain waves. During periods of drowsiness, as when you are sitting in a boring lecture and begin to drift off, EEG records indicate that brain activity fluctuates between alpha and slower, more regular waves, called theta waves. Theta waves occur at a rate of 3 to 7 waves per second and are usually associated with light sleep.

Stages of Sleep

EEG studies have shown us that sleep occurs in four stages, each with its own characteristic brain wave activity. The stages of sleep are referred to as Stage I, II, III, or IV with Stage I being the lightest stage of sleep and Stage IV being the deepest stage of sleep. Desynchronized theta waves are

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found primarily in Stage I sleep (Figure 8.4).

Like Stage I sleep, Stage II sleep is characterized by desynchronized brain waves. However, synchronized brain waves are also present in Stage II sleep, as are other hallmarks, including sleep spindles and K-complexes. Sleep spindles are bursts of brain waves with a frequency of 7 to 14 waves per second that last for several seconds and recur every 3 to 10 seconds (Steriade, McCormick, & Sejnowski, 1993). They are present in all stages of sleep but are most prevalent in Stage II sleep and are associated with a loss of perceptual awareness. On the other hand, K-complexes are seen only in Stage II sleep. K-complexes appear as large changes in measured voltage in EEG records, with a sharp positive peak followed by a sharp negative peak.

Figure 8.4: Stages of sleep Brain waves (EEG) become large, slow, and regular in Stage IV sleep, whereas they are fast, low-voltage, and irregular in REM sleep. Eye movements (EOG) increase dramatically in REM sleep, but muscle tension (EMG) disappears in REM sleep.

In Stage III sleep, synchronized brain waves called delta waves are observed, indicating a deeper stage of sleep. Delta waves are very slow, regular brain waves that occur at a rate of approximately 2 waves per second.

Stage IV sleep is associated with a preponderance of delta waves in the EEG record (Figure 8.3). That is, in Stage IV sleep, more than 50% of the EEG record indicates delta wave activity, whereas delta waves occur less than 50% of the time in Stage III sleep. During Stage IV sleep, heart rate and breathing are slow, and the individual is in the deepest stage of sleep. These stages of sleep, during which the EEG record exhibits large, slow brain waves, are often referred to collectively as slow-wave sleep or quiet sleep. Table 8.2 summarizes the characteristics of each stage of sleep.

Table 8.2: Stages of sleep

Stage EEG activity Muscle tone Eye movements

I primarily theta wave activity moderate slow, rolling

II mostly synchronized, with sleep spindles, K-complexes moderate none

III synchronized, with some delta wave activity (<50%) low to moderate none

IV >50% delta wave activity low to moderate none

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Paradoxical sleep, or REM sleep, shuts down many of the body's functions. Why is REM sleep so important to brain development, especially for newborn babies?

REM Sleep

REM desynchronized, increased brain activity none movements rapid, jerking eye

A person who falls asleep first enters Stage I. However, to fall asleep, a person must be in a relaxed state, with alpha waves present in the EEG record. Have you ever tried to sleep when you were really excited or upset about something? If you have, you undoubtedly found it tremendously difficult to fall asleep under those circumstances. When you are in a state of emotional arousal, your brain is very active, as indicated by the presence of beta waves. To fall asleep, you have to relax, slowing brain activity from 20 brain waves per second to fewer than 8 waves per second. When my son, Jacob, was quite young, he came to me one evening after he had been tucked into bed, complaining, "I can't sleep. I keep thinking about monsters." I replied, "Stop thinking about monsters. Think about something boring, like llamas. Think about llamas." Somehow my young son managed to relax and slow down his brain activity, because he was fast asleep soon after this exchange.

Thus, when a person falls asleep, he or she enters Stage I sleep, which is characterized by the presence of theta waves. As sleep continues, the person goes into Stage II, then Stage III, and finally Stage IV sleep. After spending some time in Stage IV sleep, the person moves back to Stage III, then to Stage II, and all the way back to Stage I. In fact, the entire night's sleep consists of repeated cycling from Stage I to Stage IV and back to Stage I again. This complete cycle, I → II → III → IV → III → II → I, is referred to as a sleep cycle and typically takes about 90 minutes. In general, we spend more time in Stage IV sleep during sleep cycles early in the night and spend more time in Stage I sleep during sleep cycles that occur toward morning.

REM Sleep

An interesting phenomenon occurs every 90 minutes during sleep when a person moves into Stage I sleep at the end of a sleep cycle: Brain activity increases (as indicated by the predominance of desynchronized brain waves), the heart rate and respiration rate increase, and the eyeballs begin to jerk about under the eyelids. American psychologist Nathaniel Kleitman and French psychologist Michel Jouvet discovered this unique stage of sleep at about the same time (Aserinsky & Kleitman, 1953; Jouvet & Michel, 1958). Kleitman and his students, Eugene Aserinsky and William Dement, called this stage of sleep rapid eye movement or REM sleep, due to the presence of eye movements during sleep. We spend about 20% of the night in REM sleep.

Jouvet gave REM sleep another name, paradoxical sleep, because the brain appears to be very active at the same time that the skeletal muscles are very inactive. In fact, electromyographic (EMG) recordings, which measure muscle tone, indicate that the major muscle groups have no muscle tone during paradoxical sleep. During paradoxical sleep, the body also appears to be sexually excited, as indicated by penile erection in men and vaginal lubrication in women. Men will notice that they often awaken with a penile erection in the morning. Recall from the preceding paragraph that we spend more time in Stage I sleep toward morning. This means that we are most likely to be in paradoxical or REM sleep just before we awaken and thus will be coming out of a stage of sexual arousal.

Another paradoxical feature of REM sleep is the lack of awareness of sensory stimulation despite increased activity of the thalamus and cerebral cortex (Pare & Llinas, 1995). That is, somatosensory, auditory, or olfactory stimuli can be applied to a person in REM sleep, and that person will not be consciously aware of the stimuli. However, electrical activity of the entire forebrain is virtually identical for waking and REM states, which means that a cognitive response to sensory stimuli should be induced. Pare and Llinas (1995) have suggested that REM sleep operates very much like automatic, implicit, or nonconscious processing, relying on previously stored data rather than responding to incoming sensory stimulation.

Aquatic mammals, such as whales and dolphins, show a remarkable adaptation to their watery existence: Only one cerebral hemisphere sleeps at a time, while the other hemisphere remains awake, allowing the animal to swim to the surface periodically to breathe. EEG records show

desynchronization associated with wakefulness in one hemisphere and slow synchronized brain waves in the sleeping hemisphere. Many sleep with one eye open, in order that the awake hemisphere can monitor the environment visually while the other hemisphere sleeps. Even more unusual, some species (for example, the bottlenose dolphin) have no REM sleep whatsoever, which allows the animal to swim continuously (Mukhametov, 1985, 1988).

Alcohol and other drugs that depress the central nervous system, such as barbiturates and marijuana, affect the amount of time spent in the various stages of sleep during a sleep cycle. That is, if you drink alcohol or smoke marijuana or take a barbiturate before going to bed, you will descend quickly from Stage I to Stage IV sleep, and you will spend more time than normal in Stage IV sleep. In fact, you will spend so much time in Stage IV sleep that you will not get enough REM sleep. People who take barbiturates on a regular basis find that they have very vivid dreams and horrifying nightmares when they stop using the pills. Normally, we spend about 20% of our sleeping time in REM sleep. However, following REM deprivation, people can spend over 30% of their sleep in REM. We see this REM rebound effect in individuals who are deprived of REM sleep.

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8.3 Brain Mechanisms of Sleep and Consciousness Brain lesioning and stimulation studies using animal subjects have demonstrated that a number of brain stem structures play crucial roles in sleep and consciousness. These structures include the reticular formation, locus coeruleus, raphe, and various hypothalamic and thalamic nuclei (Figure 8.5). In addition, examination of human patients who have damage to these areas reveals that these structures are also important in regulating sleep and consciousness in people. Table 8.3 summarizes the roles that these structures play. Let's take a look at each of these structures individually.

REM Sleep and the Brain

Table 8.3: Brain structures involved in sleep and consciousness

Brain structure Function

Reticular formation Produces cerebral arousal and vigilance, initiates orienting response

Raphe system Lesions of raphe produce sleeplessness in rats; stimulation induces sleep

Locus coeruleus Produces and regulates arousal; initiates a state of alert attentiveness

Suprachiasmatic nucleus (hypothalamus)

Regulates biological clock

Pineal gland Releases melatonin in response to the suprachiasmatic nucleus

Reticular thalamic nucleus In non-REM sleep, blocks transmission of sensory information to cerebrum and limbic system.

Staying Awake: The Reticular Formation

You learned about the reticular formation in Chapter 4. Moruzzi and Magoun (1949) discovered the reticular formation, and they found that stimulation of the reticular formation causes a sleeping animal to awaken suddenly. Thus, the reticular formation is important for maintaining

Figure 8.5: Sleep and consciousness

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Photo 8.3 It takes a few days for our biological clock to adjust to changes in our environment.

wakefulness and vigilance. Lesioning the reticular formation results in an inability to make orienting responses to novel or important stimuli. When Bremer (1935) lesioned the reticular formation in cats, these cats went into a state of permanent sleep and could not be awakened.

Controlling Sleep: The Raphe System

The raphe system is the principal source of the neurotransmitter serotonin in the brain. Because serotonin plays an important role in regulating sleep, the raphe undoubtedly is crucial in the control of sleep. Lesions of the raphe produce sleeplessness in rats, whereas stimulation of the raphe induces sleep (Jouvet, 1999). A case study of a patient with a tumor in the raphe system revealed that the patient was unable to sleep and remained awake for about 2 weeks until his death (Arpa, deAndres, Rodriguez, & Padrino, 1994).

Neurons in the raphe exhibit a firing pattern that is unlike that of other neurons in the brain (Jacobs, 1994). These neurons fire spontaneously at a slow, steady rate. Even when the neurons are surgically removed from the brain and cultured in a dish on the lab bench, these serotonin cells continue to fire their characteristic rhythm pattern. The rate of firing of raphe cells changes in response to alterations in the level of consciousness. For example, when an individual is relaxed but awake, the serotonin neurons fire at a rate of about three spikes per second. The number of spikes per second generated by the serotonin neurons increases when an individual is awake and aroused. As the individual falls into slow-wave (non-REM) sleep, the number of spikes per second decreases. However, during REM sleep when the cortex shows increased activation associated with dreaming, the neurons in the raphe system stop firing altogether. Just before the individual awakens, the neurons in the raphe resume their three- per-second pattern.

The Biological Clock

The suprachiasmatic nucleus of the hypothalamus is located in the anterior hypothalamus just above the optic chiasm. This nucleus has been demonstrated to play a crucial role in regulating sleep-wake cycles, or what is known as the biological clock. Research on many species indicates that each species is active at certain hours of the day and is inactive at others. Reptiles, birds, and mammals appear to undergo a period of quiescence that we call sleep. Studies of human participants have shown that most people have a rhythm, called a circadian rhythm, that is a little over 24 hours long for both young and elderly individuals (Bass & Takahashi, 2011). For most people, this means that we feel sleepy sometime during the evening and typically fall asleep within an hour or two thereafter. If we manage to stay awake past our usual sleeping time, we feel extremely tired in the middle of the night. However, toward morning, we get a second wind and feel wide awake once again.

The suprachiasmatic nucleus is believed to contain the pacemaker that controls the circadian rhythm. Not only does this rhythm regulate our levels of sleepiness and wakefulness, but it also controls hormonal levels and body temperature and metabolism (Huang et al., 2011; Schibler, Ripperger, & Brown, 2001; Wirz-Justice, 1995). For example, our body temperature reaches a peak at 8:00 p.m. and then drops throughout the night, reaching a low at about 5:00 a.m., when it starts rising again. Our brain activity and sensory abilities follow a circadian rhythm, too. At 8:00 p.m., most of our senses (taste, smell, hearing) are at a peak, and our hearing remains sharp all night. Most of our senses, including our sense of pain, are lowest in the morning.

This rhythm continues despite changes in lighting, diet, hormonal state, drugs, and illness (Richter, 1955). People and other animals living in constant light or constant darkness continue to go to sleep and wake up right on schedule according to their biological clocks. However, events in the environment can reset the biological clock. For example, if you live in New York and fly three time zones west to California, you feel very tired at 9:00 p.m. California time because your body is still on New York time (which is midnight). But in a few days, your biological clock is reset, and you adjust to California time and no longer feel like sleeping at 9:00 p.m. Any number of things can reset your biological clock, including natural or artificial light, your alarm clock, or other environmental demands. Anything that resets the biological clock is called a zeitgeber.

Many investigators now believe that genes control the biological clock. Earlier research with fruit flies and bread mold has demonstrated that circadian rhythms in these organisms are controlled by genes. More recent research with hamsters and mice has shown that their biological clocks, too, appear to be controlled by genes (Damdimopoulou et al, 2011; Morris, Viswanathan, Kuhlman, Davis, & Weitz, 1998; Antoch et al., 1997). For example, Joseph Takahashi and his colleagues at Northwestern University have located the gene, which Takahashi has labeled the Clock gene, responsible for producing the circadian rhythm in mice (Sadacca, Lamia, DeLemos, Blum, & Weitz, 2011). Mice with defective Clock genes have a circadian rhythm that is 4 hours longer than normal. Of much interest to researchers is the discovery that one segment of the gene contains the same sequence of amino acids found in the genes that control the biological clocks in fruit flies and bread mold. Similarly, Clock genes, called per genes, have also been discovered in humans. Genetic errors associated with this gene have been reported to produce sleep disorders, mood disorders, infertility, and obesity in humans and other animals (Karatsoreos et al., 2011; McClung, 2007; Miller et al., 2004; Naylor et al., 2000; Turek et al., 2005; Vanselow et al., 2006). Although no one currently understands how these genes ultimately control the biological clock, it may be that all organisms share the same basic clock mechanism.

The Effect of Light

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Photo 8.4 Melatonin capsules can be taken to adjust to different time zones quickly, as long as they are taken at the right time of day.

Information about light is relayed from the retina to the suprachiasmatic nucleus of the hypothalamus by way of the retinohypothalamic tract (Figure 8.6). The suprachiasmatic nucleus processes this information and sends it to the pineal gland. The pineal gland is a structure that is located in front of the midbrain. The main function of the pineal gland appears to be the release of a hormone called melatonin. Information from the suprachiasmatic nucleus directly affects the release of melatonin from the pineal gland. Melatonin, in turn, signals information about the environmental light/dark cycle to the rest of the brain (Arendt, 1988; Cardinali, 1981; Golombek, Pevet, & Cardinali, 1996). In addition, melatonin receptors in the suprachiasmatic nucleus permit melatonin to influence and even alter the circadian rhythm (Reppert, Weaver, Rivkees, & Stopa, 1988; Reppert 1997; Wulff et al., 2010). The "For Further Thought" box describes how melatonin can reset the biological clock.

Figure 8.6: Pathways to and from the suprachiasmatic nucleus Information from the retina reaches the suprachiasmatic nucleus via the retinohypothalamic tract. Light striking the retina causes the suprachiasmatic nucleus to signal the pineal gland to reduce its secretion of melatonin.

For Further Thought: Resetting the Biological Clock with Melatonin

The brain uses the hormone melatonin to signal the presence or absence of environmental light. This signal conveys information about the circadian cycle as well as the light changes associated with seasonal variations. Because melatonin is so closely tied to the sleep-wake cycle, it has been used to treat a number of disorders associated with disturbance of the circadian rhythm. For example, it has been used effectively to reduce sleepiness and lapses in alertness associated with jet lag and shift work (Golombek et al., 1996).

When taken as a drug, melatonin can reset the biological clock. However, the time of day has an important impact on the effect of melatonin in the body. That is, when melatonin is taken at dusk, it shifts the circadian rhythm forward, which is useful if you are traveling to a different time zone in the East. In contrast, when melatonin is taken at dawn, it shifts the biological clock backward in time, preparing a person to adjust to a new time zone in the West.

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Dreaming: The Reticular Thalamic Nucleus

The neural pathways between the thalamus and the cerebral cortex, called the thalamocortical system, appear to play an important role in determining our conscious experience (Pare & Llinas, 1995; Tononi & Edelman, 1998). Do you see the words thalamus and cortex in the term thalamocortical system? Recall that the reticular formation relays its information to the thalamus for action by the cerebrum. These areas work together to produce a unified consciousness, in which all components of the conscious experience (visual, auditory, taste, olfactory, somatosensory, data from memory, and other components) are integrated, and incongruent elements are combined or ignored (Damasio, 1999).

As you learned in Chapter 4, the thalamus acts as a filter or gate that controls the transmission of sensory information to the cerebral cortex, amygdala, and hippocampus. EEG studies have indicated that, in non-REM sleep, certain thalamic nuclei, including the reticular thalamic nucleus, produce slow synchronous oscillations that appear to block the access of sensory information to the cerebrum and limbic system (Crunelli & Hughes, 2010; Krystal et al., 1995; Steriade, McCormick, & Sejnowski, 1993). During REM sleep and wakefulness, another EEG pattern is observed in the thalamus; this pattern is believed to promote transmission of sensory stimulation to the cortex. Thus, during dreaming, the thalamocortical system sends internally generated sensory information from the limbic system to the cerebral cortex to create the experience we know as dreams.

Scientists who study brain anatomy have discovered many anatomical interconnections between the brain structures involved in cortical arousal. Interconnections exist between all of the structures described in the preceding sections, including the reticular formation, the raphe system, the locus coeruleus, and various hypothalamic and thalamic nuclei. Information appears to run in both directions, to and from these interconnected sites, which means that a good deal of data is shared among these brain structures. The unified nature of consciousness can be explained by the simultaneous activation of all of these structures (Delacour, 1995; Koch & Tononi, 2011).

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Photo 8.5 How much of a newborn baby's sleep time is spent in REM sleep?

8.4 The Function of Sleep No one knows why we sleep, although people since the dawn of humankind have tried to explain the function of sleep. Primitive people believed that, when we sleep, our spirits leave our bodies to cavort with other spirits (living and dead). According to this primitive view, dreams are a glimpse of our interactions with these other spirits. Today, the evolutionary theory of sleep is the most popular explanation among neuroscientists of sleep.

The evolutionary theory of sleep maintains that all animals occupy an environmental niche and sleep to conserve energy during times when it is dangerous to be awake. For example, humans do not see well in the dark and could not easily escape predators if they were being chased at night. For that reason, according to the evolutionary theory, people sleep at night because it's safer for them to be asleep then. Other animals, known as nocturnal animals, are active at night and sleep during the day. These animals have evolved with sensory abilities (acute olfactory and auditory senses, excellent nighttime vision) that permit them to find food and mates safely at night.

The support for the evolutionary theory of sleep is largely circumstantial. Large grazing animals, like elephants, horses, and cows, spend only a few hours sleeping and many hours each day (up to 20 hours per day) eating because their caloric needs are so great. Prey animals that have safe hiding places, such as rabbits and mice, have long periods of sleep. Prey animals that live in an open, vulnerable environment, like herding antelope, display light sleep for short periods of time. In contrast, predators like wolves and lions sleep deeply for long periods of time. A common domestic cat, for example, will sleep about 18 hours a day.

According to the evolutionary theory of sleep, humans sleep because consciousness has high energy costs. When we are awake or in REM sleep, heart rate, respiration rate, and brain activity are increased. Thus, consciousness and REM sleep are accompanied by high metabolic rates. Even when we are awake, most brain activities are unconscious. Delacour (1995) has suggested that conscious brain activity requires more energy than unconscious brain activity and that, therefore, we engage in conscious behavior sparingly. For this reason, well-learned behaviors are transferred over to the unconscious, or implicit, memory systems for execution (Kavanau, 1997). Conscious processing is reserved for new or unexpected events and for retrieving stored data from declarative memory, although there is evidence that some novel stimuli can be processed in the absence of conscious awareness (Berns, Cohen, & Mintun, 1997; Scott et al., 2011).

The Function of REM Sleep

If the function of sleep is unknown, the function of REM sleep is even more unclear. For some unknown reason, newborns spend about 50% of their sleeping time in REM sleep. What could they be dreaming about? Many investigators believe that memory consolidation occurs during REM sleep. Other investigators have suggested that REM sleep in newborns is important for strengthening neural networks. Hobson (2009) has theorized that the brain is "warming up" during REM sleep and is preparing itself for the sensations and emotions of the waking state.

Although the function of REM sleep is still unknown, we do know that deprivation of REM sleep can impair thinking and disturb behavior. For example, REM deprivation is associated with increased eating and weight gain, an inability to concentrate, and increased anxiety and irritability. When a REM-deprived person is permitted to get a full night of undisturbed sleep, REM rebound is observed. As you learned earlier in this chapter, REM rebound refers to an increase in REM sleep, which is accompanied by an increase in dreaming.

The Nature of Dreaming

Psychologists and other theorists have proposed a variety of explanations for the function of dreams. Undoubtedly, in other psychology courses, you have learned about Sigmund Freud's theory of dreams. According to Freud, dreams symbolically express our unconscious desires and fears. For example, dreaming about money, Freud believed, might indicate a person's anxiety concerning anal functions.

A more modern view of dreams is the activation-synthesis hypothesis of dreaming, proposed by J. Allan Hobson and Robert McCarley (1977). According to the activation-synthesis hypothesis, our cerebral cortex processes and interprets incoming sensory information, even during sleep. Thus, dreams arise when the brain attempts to make sense out of disjointed sensory input (for example, visual images produced by random activation of the visual system) during sleep. One morning just before awakening, I dreamed that I was at a party dancing to music; I then abruptly awoke to find that my clock radio was playing. I had obviously incorporated the music blaring from my radio into my dream.

Dement and Kleitman (1957) attempted to determine when dreaming occurs during the course of a night. Participants in their study slept in Dement and Kleitman's laboratory, with EEG electrodes pasted to their scalps to permit recording of brain activity while they slept. The investigators monitored the participants' EEG records while they slept and awakened participants during REM and non-REM sleep. When the participants were awakened during REM sleep, they reported dreaming about 80% of the time. In contrast, they reported dreaming about 20% of the time when awakened during non-REM sleep. Hence, dreaming occurs during both REM and non-REM sleep (Hartman & Zimberoff, 2012).

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Subsequent research has demonstrated that the quality of REM dreams differs from the quality of dreams generated during non-REM sleep. REM dreams are experienced as vivid and well organized, albeit sometimes illogical or fantastical (for example, dreaming that you are flying with your arms outstretched). The content of non-REM dreams is less organized and appears to be related to ongoing life events or concerns. This difference in dream content and quality may be related to differences in brain physiology during REM sleep and non-REM sleep. REM sleep is characterized by an increase in excitatory input to the cerebral cortex from the ascending reticular activating system and a reduction in inhibitory input to the cortex, with only dopamine pathways being active (Gottesmann, 1999; Hobson, 2009). Thus, dreams during REM sleep are often illogical or irrational, due to the absence of inhibitory influences that normally regulate activity in the cerebral cortex. During non-REM sleep, brain stem input to the cerebral cortex is largely inhibitory, producing less intense and more rational mental activity (Gottesmann, 1999).

Sleep Disorders

Sleep disorders tell us a great deal about the processes underlying the continuum between sleep and consciousness. Let's review a number of these disorders as we seek to understand sleeping and waking states.

Insomnia

Insomnia is a disorder in which the affected individual has difficulty falling asleep or staying asleep. All of us have had this trouble at one time or another. In fact, for people between the ages of 18 and 25, insomnia is a common problem. A person may have trouble sleeping because he or she is excited or worried about something. Recall that earlier in the chapter I stressed that a person must be in a relaxed state before sleep can occur. Sometimes a college student can get into a vicious cycle where he or she lies in bed worrying, "Here I go again. I can't fall asleep. If I don't sleep tonight, I'll be too tired to study for my exam tomorrow night. Then I'll fail the exam and end up flunking out of school." These kinds of thoughts are accompanied by beta wave activity, which is not conducive to falling asleep. Whereas younger people have trouble falling asleep, older people who experience insomnia have trouble staying asleep (Montgomery & Shepard, 2010; Reynolds, Buysse, & Kupfer, 1995).

Sometimes prescription sleep medication is prescribed for individuals who have insomnia, although most people with insomnia do not seek medical treatment for this disorder but rather use over-the-counter medications or alcohol to fall asleep (Nowell, Buysse, Morin, Reynolds, & Kupfer, 1998). Many over-the-counter medications contain antihistamines, which block histamine receptors. (Recall from Chapter 3 that histamines cause arousal of the nervous system.) Benzodiazepines have been found to be the most effective for treating insomnia. As you learned in Chapter 3, benzodiazepines bind with GABA receptors, producing relaxation.

Barbiturates can also induce sleep, but tolerance to the drugs occurs in a few days, requiring higher and higher doses to be administered to achieve sleep. Withdrawal from barbiturates can produce insomnia, increased REM sleep, and vivid nightmares (Nishino, Mignot, & Dement, 2001). Also, melatonin has been demonstrated to be somewhat useful in treating insomnia.

Relaxation exercises and meditation can help a person learn to relax and fall asleep. Other behavioral treatments include cognitive behavioral therapy, sleep restriction therapy, and stimulus control therapy. In cognitive behavioral therapy, the patient learns to identify and modify thought patterns that maintain insomnia. Sleep restriction therapy involves initially restricting the amount of time that a person has to sleep and gradually increasing the time for sleep as the person's ability to fall asleep improves. In stimulus control therapy, people with insomnia are allowed to use the bedroom only for sleep. That is, they cannot read, work, or watch television in their bedrooms and must leave their bedrooms if they are unable to sleep for 20 minutes, returning only when they feel sleepy. All of these behavioral techniques have proved to be helpful (Harsora & Kessmann, 2009; Nowell et al., 1998).

Narcolepsy

This disorder is characterized by episodes in which the affected individual suddenly loses all muscle tone and falls asleep. These sleeping attacks resemble epileptic seizures, hence the term narcolepsy. Typically, a person with narcolepsy will experience an aura, or sensory illusion, such as a particular odor or a visual image, immediately before the sleep attack, and different environmental stimuli (especially emotional stimuli) have been observed to trigger a narcoleptic episode. EEG recordings of people during a narcoleptic attack reveal that they go immediately into REM sleep when they collapse into sleep. The loss of muscle tone during a narcoleptic attack also indicates that the affected individual is in REM sleep.

However, the most prominent symptom for most people with narcolepsy is the excessive daytime sleepiness and periods of intense drowsiness that occur every 3 to 4 hours, requiring a short nap. The individual with narcolepsy is typically not aware of these periods of drowsiness and often will deny falling asleep. EEG studies of individuals with narcolepsy have revealed that narcolepsy is associated with decreased delta wave activity during non-REM sleep (Guilleminault, Heinzer, Mignot, & Black, 1998).

Narcolepsy has also been detected in dogs, and much research has been conducted on narcoleptic dogs in order to gain a better understanding of this puzzling disorder (Takahashi, 1999; Wu et al., 2011). For over a decade, William Dement has maintained a colony of narcoleptic Dobermans and Labradors at Stanford University. Because the genetic pedigree of the Stanford dogs is well known, Mignot and his colleagues have been able to identify the gene that causes canine narcolepsy (Lin et al., 1999). This gene codes for a receptor of a particular neuropeptide called orexin, which

regulates eating behavior. By inactivating the orexin gene in mice, Yanagisawa

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Photo 8.6 Although sleep apnea is much more common with adults than babies, it is notably common in premature babies.

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Photo 8.7 Night terrors take place during non-REM sleep, causing the individual to wake in a sense of autonomic arousal.

and his colleagues (Chemelli et al., 1999) have been able to produce narcoleptic attacks in mice. Investigators are uncertain as to the role that orexin plays in sleep, but recent evidence suggests that narcolepsy may be caused by the loss of cells in the hypothalamus that produce orexin (Siegel, 2000).

Sleep Apnea

The word apnea literally means "without breath" (a- means "without" and -pnea means "breath" in Latin and Greek). Thus, sleep apnea is a disorder in which breathing is temporarily suspended during sleep. This disturbance can occur at any age from birth to old age and is most prevalent in obese adults. Obviously, when an individual stops breathing, asphyxiation sets in, and death can result. Most cases of sudden infant death syndrome (SIDS), in which a healthy infant is placed in its crib and is discovered dead sometime later, have been attributed to sleep apnea. That is, in these infants, the breathing reflex is not fully developed or reliable, and when they stop breathing, the brain does not induce inhalation as it should. Sleep apnea is especially common in premature babies, who have to be monitored constantly for any signs of breathing cessation (Photo 8.6). In addition, some medications can cause sleep apnea. People taking certain

muscle relaxants, for example, may wake up gasping for air, which can be a frightening experience.

Somnambulism

Sleepwalking is the common word for somnambulism. As you learned at the beginning of this chapter, people can engage in very complicated behaviors (such as speaking in French or climbing stairs) while sleepwalking. However, sleepwalking generally occurs in non-REM sleep, when the brain is relatively inactive. This means that people are unconscious of their behavior when somnambulating. Remember that during REM sleep the major muscle groups do not have any tone and are incapable of producing movement. On the other hand, muscle tone is present during non-REM sleep, and behavior can be initiated by unconscious or implicit brain systems, out of the person's conscious control.

Nocturnal Enuresis

Nocturnal enuresis is also known as bed-wetting. Many young children have accidents and urinate in their sleep. But persistent bed-wetting after age 9 is regarded as a medical problem. Nocturnal enuresis occurs in non-REM sleep, when conscious processing is absent in the brain. Thus, bed- wetting happens unconsciously, and the person is not aware that he or she is urinating when it happens, which makes this disorder very difficult to treat (Butler, 2001; Jensen & Kristensen, 2001; Lawless & McElderry, 2001).

Psychologists employ classical conditioning to treat bed-wetting. An alarm is used as the unconditioned stimulus (US), which awakens the affected individual. (Waking is the unconditioned response, or UR, to the alarm.) This alarm is wired to a sensor that detects wetness, and the sensor is attached to the individual's pajama bottoms. Therefore, when the individual begins to urinate during sleep, the sensor detects the urine, causing the alarm to ring. Urination is the conditioned stimulus (CS) that is paired with the alarm (the US). This treatment is based on the theory that, when urination (the CS) occurs, the individual will awaken (the conditioned response, or CR).

Night Terror

A nightmare, as you know, is a "bad" dream or a dream loaded with negative emotional content. Some nightmares can be so disturbing that the autonomic arousal that they induce wakens us from our sleep. Nightmares occur typically during REM sleep. In contrast, night terror takes place during non-REM sleep. A person experiencing night terror awakens from deep sleep frightened and showing signs of autonomic arousal, including increased heart rate and blood pressure. Often the individual experiencing night terror will begin to scream and then wake up, confused and frightened. Whereas a person awaking from a nightmare can usually describe the content of the bad dream in detail, an individual awaking with night terror has no idea why he or she feels scared. Night terror is common in young children and usually disappears as they get older, although some people continue to experience night terror in adulthood.

Sleep Disorders Associated with Alterations of the Circadian Rhythm

A number of disorders are associated with alterations of the circadian rhythm, including advanced-sleep-phase syndrome, delayed-sleep-phase

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syndrome, and jet lag. Individuals with advanced-sleep-phase syndrome generally feel tired due to disturbed phasing of their circadian rhythm, several hours earlier than their normal sleep time. A person with advanced-sleep-phase syndrome, for example, may shows signs of sleepiness at 5:00 or 6:00 p.m., instead of at 10:00 or 11:00 p.m. In contrast, those with delayed-sleep-phase syndrome do not feel tired until many hours after their normal sleep time and awake much later than normal. Jet lag is caused by taking long flights that cross several time zones, which causes an abrupt shift in the sleep-wake cycle. Although it lasts only a day or so, people with jet lag feel tired and cannot think clearly during normal waking hours and have trouble falling asleep at bedtime.

Shift work can also produce sleep disorders, especially when the worker is forced to work different shifts during different weeks; for example, working 3:00 p.m. to 11:00 p.m. one week and 11:00 p.m. to 7:00 a.m. the next. Changing shifts on a weekly or monthly basis is quite disruptive for the endogenous biological clock, causing the individual to feel sleepy and inattentive while awake and to have problems falling asleep at bedtime. Sleepiness can disrupt performance and cause the sleepy person to make more mistakes than usual (Akerstedt, 1985). In addition, confused and very ill patients often have a reversed sleep-wake cycle, remaining asleep during the day and awake at night (Quera-Salva, Lemoine, & Guilleminault, 2010). Bright light has been used with some success as treatment for all of these disorders (Campbell, Dawson, & Anderson, 1993; Bjorvatn & Pallesen, 2009; Eastman, Stewart, Mahoney, Liu, & Fogg, 1994; Lack, Mercer, & Wright, 1996; Oren & Terman, 1998). Light has an activating effect, probably caused by light-induced release of norepinephrine, and it improves performance.

The research of behavioral neuroscientists is improving our understanding of the states we call sleep and consciousness. Some scholars firmly believe that we will never fully understand consciousness because of the problems presented by the mind studying the mind (Horgan, 1994). They question whether the human mind can really examine itself objectively. Nonetheless, studies that involve recording the electrical activity of the brain or functional brain imaging have greatly enhanced our knowledge of sleep and consciousness and will continue to do so in the future. Most neuroscientists today agree that consciousness results from the integration of many discrete cortical functions that are distributed across the cerebrum.

But remember that brain stem structures also play an important role in sleep and consciousness. For example, the biological clock, which determines when we sleep and when we're awake, is regulated by the suprachiasmatic nucleus of the hypothalamus. As you will learn in Chapter 9, the hypothalamus directs behaviors associated with a number of drives, in addition to the drive to sleep.

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8.5 Chapter Summary Consciousness

Consciousness refers to an awareness of one's self and one's surroundings, but investigators disagree as to its exact nature.

Metacognition is an awareness of one's own mental processes.

Consciousness appears to involve structures in the frontal lobe, especially the prefrontal cortex.

The study of disorders of consciousness has provided some insight into the nature of consciousness.

Amnesia is an impairment of declarative memory and thus interferes with conscious processing.

Goal neglect is an impairment associated with frontal lobe syndrome.

In Asperger's syndrome, individuals exhibit a consciousness that is less impaired than that observed in most autistic individuals.

Coma is a state of unconsciousness in which the eyes are closed. In contrast, a permanent vegetative state is a state of unconsciousness in which the eyes are open, but behaviors are reflexive and primitive.

Experiments with split-brain patients conducted by Roger Sperry and others have demonstrated the important role that the cerebral hemispheres play in the conscious processing of information.

Roger Sperry received a Nobel Prize for his research on consciousness in patients who have undergone a surgical division of the corpus callosum. His research demonstrated that each cerebral hemisphere has a consciousness of its own, although the left hemisphere plays a special role in consciousness because it contains the language centers.

Sleep

EEG studies using scalp electrodes have shown that synchronized brain waves are associated with deep sleep and that desynchronized brain waves are associated with active, conscious states.

Beta waves are observed when an individual is aroused, and alpha waves are associated with relaxed wakefulness.

Theta waves are found primarily in Stage I sleep, whereas sleep spindles and K-complexes are present in Stage II sleep.

Delta waves occur more than 50% of the time in Stage IV sleep and less than 50% of the time in Stage III sleep.

In REM sleep, brain activity increases, heart rate increases, skeletal muscles are inactivated (except for eye muscles, which cause the eyeballs to jerk about under closed eyelids), and sexual arousal occurs.

REM rebound is seen in people who are deprived of REM sleep.

Brain Mechanisms of Sleep and Consciousness

A number of brain structures play crucial roles in sleep and consciousness, including the reticular formation, the raphe system, the suprachiasmatic nucleus of the hypothalamus, the pineal gland, and the reticular thalamic nucleus.

The reticular formation alerts the cerebrum when important stimuli occur.

The raphe system is the principal source of serotonin in the brain and thus plays a role in regulating sleep.

The suprachiasmatic nucleus (SCN) of the hypothalamus plays a crucial role in regulating the biological clock. The SNC relays information about light to the pineal gland, which releases melatonin.

The thalamocortical system is the pathway between the thalamus and cerebral cortex that plays a role in determining our conscious experience.

The Function of Sleep

Many theories have been advanced to explain why we sleep, although the evidence for each theory is largely circumstantial.

The evolutionary theory of sleep maintains that sleep conserves energy at times when it is dangerous to be awake.

The function of REM sleep is unknown.

According to the activation-synthesis hypothesis of dreams, dreams arise when the brain tries to make sense out of incoming sensory information during sleep.

When subjects were awakened from REM sleep, they reported dreaming 80% of the time, compared to subjects awakened during non-REM sleep, who reported dreaming 20% of the time.

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Deprivation of REM sleep can impair thinking and disturb behavior, as well as produce REM rebound.

Sleep Disorders

Insomnia is a disorder in which a person has difficulty falling or staying asleep.

Antihistamines, benzodiazepines, and barbiturates can induce sleep.

Narcolepsy is characterized by excessive daytime sleepiness and episodes in which a person loses all muscle tone and falls asleep.

Sleep apnea is a disorder in which breathing is temporarily suspended during sleeping.

People with somnambulism typically sleepwalk during non-REM sleep.

Nightmares generally occur during REM sleep, and night terror takes place during non-REM sleep.

Individuals with advanced-sleep-phase syndrome generally feel tired several hours earlier than their normal sleep time due to disturbed phasing of their circadian rhythm.

Individuals with delayed-sleep-phase syndrome do not feel tired until many hours after their normal sleep time and awake much later than normal.

Jet lag is caused by taking long flights that cross several time zones, which causes an abrupt shift in the sleep-wake cycle.

Questions for Thought

1. Do dogs experience consciousness? Do autistic children experience consciousness? Explain your answers.

2. In a split-brain patient, which hemisphere is most likely to produce a sense of conscious awareness? Why?

3. Can sleepwalking occur during REM sleep? Why or why not?

4. How does shift work affect sleeping and consciousness?

5. List Delacour's criteria for consciousness and give a real-life example of each.

6. What is the difference between being in a coma and having locked-in syndrome?

7. What roles do structures in the hindbrain, hypothalamus, and thalamus play in the production of sleep and consciousness?

8. Explain the difference between advanced-sleep-phase syndrome and delayed-sleep-phase syndrome.

Chapter 8 Flashcards

Web Links

The Medline Plus website, a service of the U.S. National Library of Medicine and the National Institutes of Health, supplies information on taste and sleep disorders. Search the website for resources on insomnia, narcolepsy, sleepwalking, and other sleep disorders. http://medlineplus.gov/ (http://medlineplus.gov/)

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Search The Huffington Post's website for an article titled "Phineas Gage Brain Map Study Spotlights Neuroscience's Most Celebrated Case." This fascinating article details the study that explains why the drastic personality change Phineas Gage experienced occurred after his brain injury. http://www.huffingtonpost.com (http://www.huffingtonpost.com/)

The official website of the Nobel Prize provides an excellent summary of Sperry's split brain studies. This includes the background and importance of the studies as well as a summary of the excellent data we were able to gather because of these studies. http://www.nobelprize.org (http://www.nobelprize.org/)

Key Terms

Click on each key term to see the definition.

activation-synthesis hypothesis of dreaming (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A theory that states our cerebral cortex processes and interprets incoming sensory information during sleep; thus, dreams arise when the brain attempts to make sense out of disjointed sensory input during sleep.

advanced-sleep-phase syndrome (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which affected individuals feel tired several hours earlier than their normal sleep time.

alpha waves (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Desynchronized brain waves observed during periods of relaxed wakefulness that occur at a frequency of 8 to 12 Hz.

amnesia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder characterized by loss of declarative memory.

anterograde amnesia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The inability to form new memories for facts and events.

Asperger's syndrome (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A form of autism in which the affected individual is high functioning, with excellent language skills and evidence of metacognition.

autism (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder characterized by severe impairment of cognitive and social skills, including impaired language and social interactions and abnormal attentional processes.

beta waves (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Fast, irregular brain waves associated with states of excitation that occur at a frequency of 13 to 50 Hz.

biological clock (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A mechanism controlled by the suprachiasmatic nucleus that regulates sleep-wake cycles.

circadian rhythm (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A sleep-wake cycle that is approximately 24 hours long in most people.

Clock gene (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

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The gene responsible for producing the circadian rhythm in mice.

coma (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A state of unconsciousness in which the eyes remain closed.

consciousness (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

An awareness of one's self, one's surroundings, and one's behavior.

delayed-sleep-phase syndrome (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which affected individuals do not feel tired until many hours after their normal sleep time and awaken much later than usual.

delta waves (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Large synchronized brain waves with a frequency of 0.5 to 2.5 Hz that are observed in deeper stages of sleep.

depersonalization (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A state in which affected individuals feel as if they are outside their own body.

desynchronized brain waves (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Rapid, irregular brain waves that are observed during conscious states.

dissociative identity disorder (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A personality disorder in which an individual can exhibit a number of different personae, some of whom are unaware of the existence of other personae.

dissociative state (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which the affected individual experiences altered sensory perceptions, memory loss, and distortion of time perception and identity.

evolutionary theory of sleep (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A theory that states all animals occupy an environmental niche and sleep to conserve energy during times when it is dangerous to be awake.

flashback (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The emergence of vivid memories that causes a past event to be experienced as happening all over again.

fugue state (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

a disturbance in identity function in which an affected person does not know his or her own identity and has no memory of the past (episodic memory).

goal neglect (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which the affected person disregards instructions and ignores requirements of a task, although the person can explain the instructions or rules.

insomnia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which the affected individual has difficulty falling asleep or staying asleep.

jet lag (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

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A disturbance of the sleep-wake cycle caused by taking a long flight that crosses several time zones.

K-complexes (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Large changes in measured voltage in EEG records, with a sharp positive peak followed by a sharp negative peak; seen only in Stage II sleep.

locked-in syndrome (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which the person's motor system is detached from conscious control, although the person is fully conscious and aware.

melatonin (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A hormone that signals information about the environmental light/dark cycle to the rest of the brain.

metacognition (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

An awareness of one's own mental processes.

narcolepsy (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A sleep disorder in which an awake individual experiences seizure-like attacks in which the individual loses all muscle tone and falls asleep.

night terror (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A phenomenon that occurs during non-REM sleep in which affected individuals awaken from deep sleep frightened and showing signs of autonomic arousal.

nightmare (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A dream loaded with negative emotional content.

nocturnal enuresis (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Bed-wetting, which occurs in non-REM sleep.

pineal gland (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A brain structure that releases melatonin.

psychogenic amnesia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A memory disorder associated with stress or psychological trauma in which memories about one's own life cannot be retrieved.

raphe system (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A hindbrain area that produces serotonin and regulates sleep behavior.

REM rebound effect (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

An increase in REM that is observed in people who have been deprived of REM sleep.

REM sleep (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A sleep stage in which desynchronized brain waves predominate and the sleeping individual's eyeballs move rapidly in a jerky fashion under closed eyelids.

reticular thalamic nucleus (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

10/14/20, 7)30 AMPrint

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A nucleus in the thalamus that blocks access of sensory information to the cerebrum and limbic system.

retrograde amnesia (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

When a person does not remember events that occurred before the time of brain injury. Memory loss can span a few hours, a few days, or a few years prior to the injury.

reversed sleep-wake cycle (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which the affected individual remains asleep during the day and is awake at night.

sleep apnea (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A disorder in which breathing is temporarily suspended during sleep.

sleep cycle (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A complete cycle from Stage I sleep down to Stage IV sleep and back to Stage I that lasts approximately 90 minutes.

sleep spindles (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Bursts of brain waves with a frequency of 7 to 14 waves per second that last for several seconds and recur every 3 to 10 seconds; they are present in all stages of sleep but are most prevalent in Stage II sleep and are associated with a loss of perceptual awareness.

somnambulism (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Sleepwalking.

split-brain patients (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Individuals who have undergone a surgery that severs their corpus callosum.

Stage I sleep (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The lightest stage of sleep characterized by desynchronized theta waves.

Stage II sleep (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The stage of sleep characterized by desynchronized brain waves, sleep spindles, and K-complexes.

Stage III sleep (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The stage of sleep characterized by less than 50% synchronized delta waves.

Stage IV sleep (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

The deepest stage of sleep characterized by more than 50% synchronized delta waves.

suprachiasmatic nucleus (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A nucleus of the hypothalamus that controls the biological clock.

synchronized brain waves (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Large, slow, regular waves associated with deep sleep.

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theta waves (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Slow, irregular brain waves associated with Stage I sleep that occur at a rate of 3-7 Hz.

yohimbine (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

A drug that blocks the alpha-2 adrenergic receptor and produces an increase in the release of norepinephrine, causing panic attacks, feelings of dissociation, and flashbacks in individuals with post-traumatic stress disorder.

zeitgeber (http://content.thuzelearning.com/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover#)

Anything, such as light or an alarm clock, that resets the biological clock.