Discussion 2: Neurotransmitters: DUE IN 8 hours

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Neurotransmitters and Related Drugs

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Learning Objectives

After completing this chapter, you should be able to:

Name the neurotransmitter families and the neurotransmitters associated with each family.

Identify the neurotransmitters not associated with neurotransmitter families.

Describe the functions of acetylcholine in the central, somatic, and parasympathetic nervous systems.

Explain how nicotine, curare, muscarine, and atropine affect the nervous system and behavior.

Differentiate between the function of glutamate and GABA in the nervous system.

Identify several peptide neurotransmitters and their functions.

Explain the differences among the monoamine neurotransmitters: serotonin, norepinephrine, and dopamine.

Describe the relationship between cannabinoid neurotransmitters and marijuana.

List several ways in which nitric oxide affects the nervous system and behavior.

Draw a synapse between two neurons and indicate where acetylcholinesterase, MAO, COMT, and SSRIs have their effect.

Matt celebrated his 21st birthday with a keg party at his apartment. The first few beers went down smoothly, and he felt no ill effects from the alcohol at first. However, when he began dancing with his girlfriend, he found that he lost his balance easily and that he could not coordinate his movements to the music.

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As the party continued, Matt drank several more beers. He soon began staggering around the apartment, hugging the walls as he moved from one room to the next. When people talked to him, he had a hard time following the conversation. His speech became slurred and effortful. After a few more beers, Matt nearly fell over when his girlfriend kissed him. She giggled and led him to his bedroom, where he staggered to his bed, lay down, and promptly fell asleep.

This chapter will focus on the chemicals that influence the activity of neurons. Some of these chemicals are neurotransmitters manufactured by the neurons themselves, and some are substances such as alcohol that are ingested and then transported across the blood-brain barrier. Alcohol is a good example of an ingested substance that affects the functioning of neurons. The opening text describes how overconsumption of alcohol affected Matt's nervous system.

Let's consider how alcohol affects neurons. Recall from Chapter 2 that in order to excite a neuron, the membrane must be depolarized. Depolarization takes place when positively charged sodium ions flow into the neuron. Alcohol blocks the flow of sodium into the neuron by binding with a protein on the surface of the cell membrane, thereby preventing the cell from getting excited. That's why alcohol is classified as a depressant: It depresses, or decreases, the activity of neurons. In the opening text, alcohol interfered with Matt's ability to walk, talk, and maintain his balance by inhibiting the neurons that control these functions.

All chemicals that affect neurons cause a change in the activity of neurons. Some chemicals, like alcohol, decrease the activity of neurons, and other chemicals increase the activity of neurons. The chemicals produced by neurons, called neurotransmitters, typically affect a neuron's activity by opening particular ion channels. As you learned in Chapter 2, opening sodium channels increases a neuron's activity because sodium rushes into the neuron when the sodium channel is open, depolarizing the neuron. Chemicals that open potassium or chloride channels of a neuron inhibit a neuron by hyperpolarizing the neuron and making the neuron less likely to get excited.

The control of behavior is a very complicated process, involving chemicals that play different roles depending on their location in the nervous system, as you will learn in Chapter 4. Don't forget that many chemicals that come from outside the body also bind with postsynaptic receptors. In this chapter we will consider the effects of various drugs on behavior.

Psychopharmacology is the study of chemical substances that affect the activity of neurons. Therefore, much of the information that we have about drug action in the brain comes from the research of psychopharmacologists. Some drugs are classified as agonists, and others are classified as antagonists. Agonists are chemical substances that bind with a receptor and activate the receptor, much as a neurotransmitter does. In contrast, antagonists also bind with a receptor, but they block the action of the neurotransmitter by preventing the neurotransmitter from binding with its receptor (Figure 3.1). We will examine the roles of well-known neurotransmitter agonists and antagonists in this chapter.

Figure 3.1: Action of agonists and antagonists

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3.1 Classifying Neurotransmitters In this section we will examine a wide variety of chemicals, called neurotransmitters, that are synthesized and used by neurons to transmit information across chemical synapses. Dozens of these transmitter substances have been identified. However, this chapter will focus only on the neurotransmitters that play an important role in the regulation of human behavior. These neurotransmitters are listed in Table 3.1.

Another type of chemical, called a hormone, is synthesized by certain brain structures or by organs outside of the brain, is released into the bloodstream, and travels to target neurons. Hormones generally have longer lasting effects on the action of neurons. For example, epinephrine, which is also known as adrenaline, is a hormone that is released by the adrenal gland, a structure located above the kidney. When released into the bloodstream, epinephrine travels to neurons in the sympathetic nervous system, activating those neurons and producing the physiological effects that we associate with sympathetic arousal: increased heart rate, rapid breathing, pupil dilation, constriction of blood vessels in the gut, and increased flow of blood to skeletal muscles (Figure 3.2).

Figure 3.2: Action of epinephrine Epinephrine affects many areas of the body. What causes your brain to release epinephrine in your body to cause these reactions?

Neurotransmitter Families

Neuroscientists have attempted to classify neurotransmitters and group them into "families" (Table 3.1). But neurotransmitters are difficult to classify due to their wide variety. However, some are easy to group together. For example, some neurotransmitters are simple amino acids, like glutamate or gamma-aminobutyric acid (GABA). Amino acids are relatively simple compounds that contain an NH2 (amino) group and COOH (acid) group.

Peptides such as endorphin and cholecystokinin form another class of neurotransmitters. Peptides are nothing more than a short chain of amino acids joined end to end.

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Photo 3.1 Carbohydrates contain large amounts of tryptophan and, when consumed, produce serotonin in your brain.

Another well-known family of neurotransmitters is the monoamine family, which are derivatives of amino acids that contain one amine (NH2) group.

Monoamines that have been demonstrated to act as neurotransmitters include serotonin, norepinephrine, and dopamine. Serotonin, the neurotransmitter associated with positive mood and satisfaction, is derived from the amino acid tryptophan, which is found in foods that you eat every day, such as red meat, fish, poultry, eggs, milk, cheese, chocolate, and oats. In fact, there is evidence that you can alter brain serotonin levels by changing your diet (see the "For Further Thought" box). Norepinephrine and dopamine come from another amino acid, tyrosine, which is commonly found in a variety of protein-rich foods.

Table 3.1: Important neurotransmitters associated with human behavior

Family name Associated neurotransmitters

Amino acid Glutamate, aspartate, glycine, gamma-aminobutyricacid (GABA)

Peptide Substance P, cholecystokinin, endorphins

Monoamine Serotonin, norepinephrine, dopamine, histamine

Cannabinoids Anandamide

Unknown Acetylcholine

Unknown Nitric oxide

Another recently identified family of neurotransmitters is the cannabinoid family. These neurotransmitters bind with a group of receptors called cannabinoid receptors. The term cannabinoid refers to any natural or synthetic chemical substances that resemble tetrahydrocannabinol (THC), the active ingredient of marijuana, in structure and function. Several neurotransmitters have been discovered that bind with cannabinoid receptors, which will be discussed later in the chapter.

Other transmitter substances synthesized by neurons, such as acetylcholine and nitric oxide, do not fit neatly into a particular family of neurotransmitters. These substances are not derived from amino acids. Nitric oxide, for example, contains no carbon and is an inorganic compound. Perhaps in the future, neuroscientists will discover related chemicals that function as neurotransmitters. For the present, acetylcholine and nitric oxide are the sole occupants of their respective family trees (Table 3.1).

For Further Thought: Serotonin and Diet

What you eat can affect serotonin levels in your brain. Recall that serotonin is derived from the amino acid tryptophan. When tryptophan crosses the blood-brain barrier, it is converted to serotonin. However, tryptophan has to compete with other large amino acids to get into the brain. Because tryptophan is present in very small quantities in most foods, especially compared to other large amino acids, it is usually outnumbered by molecules of other amino acids vying to cross the blood-brain barrier and cannot easily get into the brain.

Foods high in protein contain relatively large quantities of other amino acids, compared to tryptophan. Thus, consuming foods rich in protein tends to prevent tryptophan from crossing the blood-brain barrier. In contrast, foods that are poor in protein have tiny amounts of all amino acids. This means that, when low-protein foods are consumed, tryptophan has less competition when crossing the blood-brain barrier and enters the brain more readily. Research has demonstrated that meals that contain less than 5% protein cause an increase in serotonin production in the brain (Fernstrom, 1987).

In addition, meals rich in carbohydrates promote the passage of tryptophan across the blood-brain barrier. Carbohydrates stimulate the release of insulin in the body, and the

more carbohydrates consumed, the more insulin is released. Tryptophan requires insulin to cross the blood-brain barrier, which means that larger quantities of insulin in the blood will transport larger amounts of tryptophan into the brain. Hence, meals rich in carbohydrates and poor in protein will facilitate the entry of tryptophan into the brain, resulting in increased synthesis of serotonin, which in turn may elevate mood (Silverstone, 1993).

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Photo 3.2 The drug Botox, used to remove wrinkles, is a toxin produced from the same bacteria that causes botulism.

3.2 The Roles of Neurotransmitters in Human Behavior Let's examine the roles that major neurotransmitters play in regulating human behavior. We'll begin our discussion with acetylcholine, the first neurotransmitter to be discovered. Next, we'll take a look at the major amino acid, peptide, and monoamine transmitter substances, and we'll conclude with a discussion of two recently discovered neurotransmitters: nitric oxide and anandamide.

Acetylcholine

Acetylcholine is believed to play an important role in a wide range of behaviors. For that reason, acetylcholine receptors are found throughout the central and peripheral nervous systems. Table 3.2 lists the functions of acetylcholine in the nervous system.

Table 3.2: Functions of acetylcholine

Nervous system Function

1. Central Learning, memory, decision making, antiexcitation, control of posture

2. Peripheral

    a. Somatic Contraction of skeletal muscles

    b. Autonomic

      i. Parasympathetic Contraction of smooth muscles, digestion, relaxation

Acetylcholine is the neurotransmitter that initiates contractions in all smooth and skeletal muscles, as you will learn in Chapter 5. Thus, acetylcholine is necessary for the functioning of the somatic and autonomic nervous systems. Chemicals such as cobra snake venom that block the action of acetylcholine can interfere with muscle contraction, causing paralysis. Curare, for example, is derived from a South American plant and is still used by native hunters there as a poison on the tip of their arrows. When a curare-tipped arrow strikes a prey animal, the curare binds with acetylcholine receptors in the animal, preventing acetylcholine from reaching its muscle receptors. Consequently, the animal becomes paralyzed and drops to the ground, which makes it easy to capture. Curare has several useful medical applications because of its ability to paralyze muscles.

Two life-threatening illnesses caused by bacteria are associated with the interference of acetylcholine transmission in skeletal muscles. Tetanus, also known as "lockjaw," usually results from a deep puncture wound that is not cleaned properly, allowing the bacterium Clostridium tetani to multiply in the area surrounding the wound. The Clostridium bacterium produces a powerful toxin (poison) that is released into the bloodstream and interferes with acetylcholine function by blocking the release of neurotransmitters that inhibit acetylcholine. That is, the tetanus toxin stops the inhibition of muscle contraction. A person afflicted with tetanus experiences prolonged, unmitigated muscle contractions that can lead to death, if not treated.

Another illness, known as botulism, results from ingestion of a bacterium called Clostridium botulinum, which is found in canned and preserved foods that have not been properly prepared. This bacterium, after it is ingested, is not destroyed by enzymes in the digestive tract and gets into the bloodstream, where it multiplies and produces a toxin that inhibits acetylcholine release at the junction between the motor neuron and the muscle fiber (Baskaran et al., 2013; Pellizzari, Rossetto, Schiavo, & Montecucco, 1999). Botulism causes weakness and eventual paralysis of all skeletal muscles, including the muscles needed for breathing. Death due to suffocation results in several hours to days if the illness goes untreated.

The drug Botox is derived from the toxin produced by the Clostridium botulinum bacterium. When injected in tiny doses directly into the muscles of the face, Botox paralyzes these muscles, removing wrinkles from the face, especially the frown lines around the eyes. This treatment, favored by movie stars and other celebrities because it is noninvasive, will last up to 8 months.

In addition to the important role that acetylcholine plays in muscle contraction, acetylcholine plays a number of other important roles in the central and peripheral nervous systems. In the autonomic division of the peripheral nervous system, acetylcholine activates the parasympathetic nervous system, producing a variety of responses associated with relaxation, including decreased heart rate, increased rhythmic contractions in the stomach and intestines, constriction of the pupil of the eye, and increased secretions of various glands associated with digestion, including salivary glands. Acetylcholine also plays an important role in the central nervous system, particularly in learning, memory, attention, decision making, reduction in anxiety, and the control of posture (Blokland, 1996; Decker, Brioni, Bannon, & Arneric, 1995; Edmonds, Gibb, & Colquhoun, 1995; Ehlert, Roeske, & Yamamura, 1995; Felder et al., 2001; Levin & Simon, 1998; McGehee & Role, 1995; Mesulam, 1995; Picciotto, Higley, & Mineur, 2012; Reiner & Fibiger, 1995; Schwarz et al., 1999).

Drugs Associated with Acetylcholine Receptors

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There are two types of acetylcholine receptors in the nervous system: (1) a receptor that binds with nicotine, called a nicotinic receptor; and (2) a receptor that binds with muscarine (a deadly toxin that comes from a poisonous mushroom), called a muscarinic receptor. Nicotine and muscarine are able to bind with acetylcholine receptors because they resemble acetylcholine structurally. A chemical fits into a receptor site like a key fits into a lock, so any chemical substance that has the correct shape will fit into the receptor and bind with it.

Keeping in mind that there are two major classes of acetylcholine receptors, you shouldn't be surprised to learn that totally different chemical substances bind to nicotinic and muscarinic acetylcholine receptors. Curare, which you learned about earlier in this chapter, binds with nicotinic receptors and prevents acetylcholine from activating the receptor. Because it blocks the action of acetylcholine, curare is a nicotinic antagonist.

Nicotine, on the other hand, is a nicotinic agonist. Whether derived from tobacco or from nicotine gum or patches, nicotine enters the bloodstream, crosses the blood-brain barrier, and activates nicotinic receptors. This is because nicotine has a molecular shape that is very similar to the acetylcholine molecule (Domino, 1998; Grimster et al., 2012). Nicotine has been demonstrated to improve cognitive processing, increase cerebral blood flow, and decrease anxiety—functions associated with activation of nicotinic receptors (Decker, Brioni, Bannon, & Arneric, 1995; Rowland et al., 2010).

If you don't remember the difference between an agonist and antagonist, this is a good time to review these terms. Figure 3.1 illustrates how the actions of agonists and antagonists differ. Drugs and other chemicals that affect neurons act as agonists or antagonists for a particular neurotransmitter. Nicotine is an acetylcholine agonist because it activates the action of acetylcholine, and curare is an acetylcholine antagonist because it blocks the action of acetylcholine.

You have already learned about one agonist of the muscarinic acetylcholine receptor, muscarine. Muscarine binds with the muscarinic receptor, producing a number of parasympathetic responses, including constriction of the pupil of the eye (Scott & Fryer, 2012). A muscarinic antagonist that has a number of medical applications is atropine. Like muscarine, nicotine, and curare, atropine is a natural substance that is derived from a plant. It can fit into the muscarinic receptor and prevent acetylcholine from binding with the receptor.

In ancient times atropine was used as a poison. Today it has many useful medical applications. For example, it is used to produce dilation of the pupil so that the physician may examine the interior of the eyeball. If you have had your pupils dilated by an eye doctor, you have experienced the effects of atropine. Remember, muscarine has the opposite effect: pupillary constriction. Table 3.3 summarizes the agonists and antagonists associated with acetylcholine receptors.

Table 3.3: Review of acetylcholine agonists and antagonists

Type of acetylcholine receptor Example of an agonist Example of an antagonist

Nicotinic Nicotine Curare

Muscarinic Muscarine Atropine

Amino Acid Neurotransmitters: Glutamate and GABA

Amino acid neurotransmitters are the most common transmitter substances found in the human nervous system. Unfortunately, because amino acids are found inside all cells in the body, scientists overlooked their role as neurotransmitters for many years. Receptors for the amino acids—glutamate, aspartate, glycine, and gamma-aminobutyric acid—have been identified in the cell membranes of neurons, and these amino acids are now regarded as true neurotransmitters. Glutamate and aspartate bind with receptors that open sodium channels and are excitatory neurotransmitters. Glycine and gamma-aminobutyric acid open chloride channels and are inhibitory neurotransmitters. We'll focus on glutamate and GABA in this chapter because the roles of glutamate and GABA in regulating human behavior are well documented, whereas the functions of glycine and aspartate are not well understood.

Glutamate

Research has demonstrated that there are at least 13 different receptors for glutamate, so the functions of glutamate are numerous. Most neurons in the brain use glutamate to produce rapid excitation in postsynaptic neurons. Glutamate is also believed to play an important role in the encoding of long-term memory and the storage of information in the brain. In Chapter 13 we'll examine the role of glutamate in brain damage and several degenerative brain diseases such as Alzheimer's disease.

Chemicals Associated with Glutamate Receptors

Although a large number of synthetic drugs have been created that bind with glutamate receptors, we will focus on two better-known chemical substances that we encounter every day. The first substance is caffeine, which is found in most coffee, tea, and carbonated beverages. Caffeine's main effect is to increase the activity of glutamate receptors that activate the heart muscle, which elevates cardiac output and increases the flow of oxygen to the brain. Caffeine does not bind with glutamate receptors directly, but instead it blocks the action of adenosine, a neurotransmitter that inhibits glutamate release. That is, caffeine binds with adenosine receptors, preventing adenosine from binding with its own receptors. When

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adenosine cannot bind with its own receptors, it cannot inhibit the release of glutamate. Thus, caffeine blocks the action of adenosine and indirectly increases glutamate release.

A second substance that is associated with glutamate receptors is monosodium glutamate, also known as MSG, which is used in some types of cuisine to enhance the flavor of food. (Chinese restaurants, for example, typically use MSG in their dishes, although some do not use MSG and promote themselves as being MSG-free.) MSG does not cross the blood-brain barrier, so it has no effect on the brain. However, because the blood- brain barrier is not fully developed in the very young, MSG can cross the blood-brain barrier in young children. MSG does bind with glutamate receptors in the peripheral nervous system and can produce tingling, burning, loss of sensation, ringing in the ears, and other peripheral symptoms in people who are sensitive to MSG or who have ingested too much of the substance (Settipane, 1987).

GABA

Gamma-aminobutyric acid (GABA) is considered to be the most important inhibitory neurotransmitter in the brain (Paul, 1995). A wide variety of different GABA receptors have been discovered in the human nervous system. Therefore, like the other neurotransmitters we have considered to this point, GABA plays a number of different roles in the brain, many of them still undiscovered.

One GABA receptor that has received a great deal of study is called the GABAA receptor. It is a large complex that contains receptor sites for other

substances in addition to GABA. Figure 3.3 illustrates a typical GABAA receptor. The receptor itself is a protein composed of five subunits that form an ion channel. It is embedded in the cell membrane, with receptor sites for GABA located on the surface of the neuron. Some subunits also have receptor sites for other substances, including alcohol, antianxiety agents known as benzodiazepines (for example, Valium), barbiturates (sleeping pills), and general anesthetics (Mihic, Sanna, Whiting, & Harris, 1995; Tan, Rudolph, & Lüscher, 2011) that stimulate GABA activity and act as GABA agonists.

Figure 3.3: The GABAA receptor complex The GABAA receptor complex is a complicated structure that contains binding sites for GABA, barbiturates, and antianxiety drugs (benzodiazepines).

Although investigators are beginning to understand the structure of GABA receptors, they are still far away from linking specific receptor types to specific behaviors. Certainly, the wide variety of GABA receptors that exist point to an enormous range of behaviors and functions that are regulated by GABA (Eulenburg & Gomeza, 2010). Some investigators believe that very minor alterations in the GABA receptor structure can profoundly affect receptor function and may be implicated in a number of behavior disorders, including anxiety disorders, alcohol abuse, epilepsy, sleep disorders, and certain degenerative disorders such as Huntington's disease (Ali, Jha, Kaur, & Mallick, 1999; Luchetti et al., 2011; Malizia & Richardson, 1995; Mihic, Sanna, Whiting, & Harris, 1995).

Drugs Associated with GABA Receptors

Many chemical substances are associated with the GABA receptors. For example, a variety of compounds have been synthesized that bind directly with the GABA receptor site, acting as GABA agonists or antagonists. These compounds are useful for research purposes when comparing the various receptor types, but they are not important for you, the student of behavior, to study. Instead, we will focus on several well-known drugs that bind with the GABA receptor. The drugs we will examine in this context are benzodiazepines, barbiturates, alcohol, and general anesthetics.

Benzodiazepines are a class of drugs that were first developed in the 1950s (Ballenger, 1995). These drugs are chiefly prescribed as antianxiety agents and have sedative and muscle relaxant effects as well. Valium is probably the best-known benzodiazepine—in fact, it was once the most widely prescribed drug in America. Benzodiazepines can also be used to control epileptic convulsions. In 1977 several investigators working in different laboratories discovered that benzodiazepines bind to receptor sites on GABAA receptor complexes. Benzodiazepines boost GABA activity

by increasing GABA binding to its receptor.

Like benzodiazepines, barbiturates are antiepileptic agents, but they are also used to induce sleep or unconsciousness in patients. Drugs that induce sleep are called hypnotics; drugs that induce unconsciousness are called general anesthetics. Barbiturates can be used as an antiepileptic, a

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Photo 3.3 Heroin was once an over-the- counter pain remedy.

hypnotic, or a brief-acting general anesthetic. They bind to the GABAA receptor complex much as benzodiazepines do (Figure 3.3; Paul, 1995; Tan,

Rudolph, & Lüscher, 2011).

Alcohol also binds to specific sites on the GABAA receptor complex. Similar to benzodiazepine in action, alcohol augments GABA binding to its

receptor, producing increased inhibition. This inhibitory action most likely produces the anxiety-reducing and sedative effects of alcohol. General anesthetics, used during surgery to induce unconsciousness in the surgical patient, also bind with the GABAA receptor, increasing the inhibitory

function of GABA (Mihic, Sanna, Whiting, & Harris, 1995). Thus, it appears that one of GABA's functions in the brain is to calm a person down and to induce sleep and unconsciousness as GABA activity increases.

Peptide Neurotransmitters

Neuroscientists have identified nearly 50 different peptides that are made by neurons and used as transmitter substances. These peptide neurotransmitters, or neuropeptides, as they're often called, differ from other neurotransmitters because they are synthesized in ribosomes in the soma of the neuron, whereas other neurotransmitters are manufactured in the axon near the site of release. In addition, peptide neurotransmitters are almost always released by the presynaptic neuron in conjunction with another neurotransmitter (Hökfelt, Castel, Morino, Zhang, & Dagerlind, 1995; Matthews & Fuchs, 2010). This observation (that neuropeptides do not act alone as a signaling transmitter) has raised many questions about the role of peptides as neurotransmitters. Most neuroscientists believe that neuropeptides enrich the message of the other neurotransmitter. At present, the functions of very few peptide neurotransmitters are truly understood. We will focus on only three neuropeptides in this chapter, although you will learn about more in later chapters.

Substance P

Substance P gets its funny name from the fact that it was first identified as an active substance in a powder made from brain extract. It is found in many parts of the brain and spinal cord, especially those parts of the nervous system associated with the sensation of pain. Currently, substance P is believed to be the primary neurotransmitter that signals pain.

Several investigators have demonstrated that substance P is released in response to stress and that it may play a role in depression, as you will learn in Chapter 12 (Burnet & Harrison, 2000; Ratti et al., 2011; Kramer et al., 1998; Wahlestedt, 1998).

Cholecystokinin

Cholecystokinin (CCK) is a hormone synthesized by cells in the small intestine and in the nervous system. It is released into the blood and travels to the central nervous system, where it binds with CCK receptors on neurons. CCK's main function involves transmitting signals about satiation following a meal. However, CCK also appears to play a role in blocking pain and reducing anxiety (Marchand & Gaumond, 2013).

Endorphins and Other Endogenous Opiate Peptides

The term endorphin is actually a contraction of the term endogenous morphine, so called because this class of neuropeptides functions like morphine in countering pain and reducing stress. Morphine is a synthetic drug that mimics the painkilling effect of opium, a natural substance derived from the poppy plant. Endorphin is a class of morphine-like chemicals, referred to as endogenous opiate peptides, manufactured by certain neurons in the brain.

At least six different peptides have been identified as endogenous opiate peptides. Endogenous opiate peptides bind with opioid receptors on the membranes of neurons. In addition to reducing pain, endogenous opiate peptides have also been implicated in the regulation of blood pressure, stress responses, food intake, sexual behavior, temperature regulation, and memory (Bodnar, 2012).

Drugs Associated with Opioid Receptors

Usually, neurotransmitters are first identified by neuroscientists, and then their respective receptors are located and characterized. In the case of endorphins, these two steps were reversed. The opioid receptor was isolated and identified first, and then researchers discovered the endogenous transmitter that binds to the receptor (Snyder, 1980.) Why was this discovery process reversed for opioid receptors?

Opium, a derivative of the poppy plant, has been known for centuries to produce sedation and euphoria in the user. Other drugs that are derived naturally or synthetically from opium, called opiates or narcotics, were developed in the 19th and 20th centuries. These new opiates, including morphine, heroin, codeine, and Demerol, were effective in reducing pain. Researchers reasoned that opium and its derivatives must interact with neurons to produce their effects, and some began searching for receptor sites on neurons that bind with opiates. In 1973 Candice Pert and Solomon Snyder at Johns Hopkins University discovered the receptor binding site for opiate drugs. After the opioid receptor was identified, investigators embarked on a search for chemicals in the nervous system that bind to the opioid receptor. In 1974 and 1975 researchers in Europe and the United

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States found a brain extract (later called endorphin) that binds to the opioid receptor (Hughes, 1975; Pasternak, Goodman, & Snyder, 1975; Terenius & Wahlstrom, 1975). Hence, the discovery of the opioid receptors in the brain that prompted the search for endorphins.

Monoamine Neurotransmitters

Earlier in this section on neurotransmitters, you learned that serotonin, norepinephrine, and dopamine belong to the same family, called monoamine neurotransmitters. Collectively, these neurotransmitters play an important role in regulating mood, sleep, appetite, and memory (Choi & Son, 2013). Individually, these three neurotransmitters each have a particular distribution in the brain and have been implicated in special functions. Other amines such as histamine have been identified in the central nervous system, but their roles are unclear at present. Therefore, we will focus on serotonin, norepinephrine, and dopamine in this section.

Serotonin

Serotonin was discovered more than 100 years ago in the serum of blood; hence its prefix sero-. The suffix -tonin comes from the observation that this blood-borne substance increases muscle tone in smooth muscle in the gut (Watts, Priestley, & Thompson, 2009). Recall that serotonin is derived from the amino acid tryptophan and therefore has the chemical name hydroxytryptamine (abbreviated as 5-HT).

Seven classes of serotonin receptors have been identified, each with its own distribution in the brain and its own function. For example, one type of receptor is implicated in anxiety, aggression, and depression, whereas another type seems to be involved in appetite and motor control, and a third type appears to play a role in nausea, vomiting, anxiety, and schizophrenia (Di Giovanni, Esposito, & Di Matteo, 2010). The fact that serotonin has so many different types of receptors tells us that serotonin plays many roles in the brain. In fact, no other neurotransmitter has been implicated in so many important human functions (Jacobs & Fornal, 1995).

Serotonin's most important function appears to be the regulation of sleep. But, it has also been demonstrated to be involved in vigilance, mood regulation, stereotyped or repetitive movements such as response to pain, and appetite (especially appetite for carbohydrates). For example, a study on diabetic patients reveals that reduced brain serotonin levels may be recovered by increased carbohydrate consumption (Yu et al., 2013). As you will learn in later chapters, serotonin has also been implicated in a host of disorders, including mood disorders, anxiety disorders, obsessive- compulsive disorder, schizophrenia, eating disorders, migraine headaches, and sleep disorders (Elliot, Zahn, Deakin, & Anderson, 2011; Marino et al., 2010; Price & Drevets, 2012).

Drugs Associated with Serotonin Receptors

Given that there are at least 15 different types of serotonin receptors, there are dozens of drugs that could be discussed in this section. However, the discussion will be limited to two illicit drugs, lysergic acid diethylamide (LSD) and methylene-dioxymethamphetamine (MDMA), that appear to interact with serotonin receptors but that are not generally prescribed for medical purposes. The molecular structure of LSD is strikingly similar to that of serotonin, and, hence, LSD is able to fit into serotonin receptor sites. LSD's effect is hallucinogenic, producing hallucinations and altering cognition and sensory experiences. The active ingredient in psychedelic mushrooms, called psilocybin, also resembles serotonin in chemical structure. Like LSD, psilocybin fits into the serotonin receptor and causes hallucinations.

MDMA, known as ecstasy for the short-term surge of euphoria and feeling of well-being that it produces, also binds with certain serotonin receptors. However, exposure to MDMA appears to be toxic to neurons. Damage to the axons of serotonin neurons has been observed in the brains of people who have taken MDMA more than 200 times (McCann, Szabo, Scheffel, Dannals, & Ricaurte, 1998). Using a radiolabel that binds to serotonin markers on the axons of neurons that release serotonin, McCann and colleagues (1998) were able to show in brain scans that axon terminals in serotonin neurons were destroyed in human subjects who used large doses of MDMA over the course of 4 to 5 years, compared to control subjects who had never used MDMA. This damage was dose-related because the damage observed was greater in subjects who used MDMA more times (400 versus 100 doses).

Norepinephrine

Norepinephrine and its catecholamine cousin, epinephrine, bind to the same receptors called adrenergic receptors. Altogether, there are four types of adrenergic receptors, each having its own agonists and antagonists and each having its own distribution in the brain. It is quite interesting that a neurotransmitter (norepinephrine) and a hormone (epinephrine) would bind to the same receptors, but it tells us that both norepinephrine and epinephrine are involved in activation of the sympathetic nervous system. Both produce an increase in heart rate, respiration rate, sweating, and pupil dilation. In addition, norepinephrine plays a role in mood, drive reduction, sleep, arousal, cognition, and emotions (Foote & Aston-Jones, 1995; Morilak, 1997). Norepinephrine also has been implicated in a number of behavioral disorders, including depression, posttraumatic stress disorder, anxiety disorder, and withdrawal symptoms associated with drug addiction (Economidou et al., 2012; Kelley & Dantzer, 2011). You will learn a great deal more about norepinephrine in Chapters 8 through 12 as we discuss sleep, eating, sexual behavior, emotions, addiction, and response to stress.

Drugs Associated with Adrenergic Receptors

Recall that the four types of adrenergic receptors each have their own agonists and antagonists. That means that we could discuss any of a large

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Although pushed as a healthier choice, marijuana has been proven to have toxic effects. Marijuana is also considered a psychoactive drug that appears to affect brain receptors. What are its effects on brain chemistry?

Effects of Marijuana Use

number of possible drugs here. This section will focus on two drugs, clonidine and yohimbine, because they have important implications for human behavior. Clonidine is an agonist of one type of adrenergic receptor, and yohimbine is an antagonist of the same receptor type. Because these two drugs have opposite effects on the same receptor, you would expect them to have opposing behavioral effects—and they do! Clonidine has a sedative or calming effect when administered, whereas yohimbine agitates the subject and can provoke anxiety (Banna, Back, Do, & See, 2010).

Dopamine

Dopamine is considered by some investigators to be the most important catecholamine in the brain (Hasbi, O'Dowd, & George, 2011). Dopamine has its own receptors, a total of five different types, and is distributed along four major pathways in the brain (Baldessarini & Tarazi, 1996). Each dopamine pathway in the brain is associated with a different function of dopamine: motor control, thinking, affect, and hormone secretion. In addition, dopamine has been implicated in the control of emotions and feelings of pleasure and euphoria. An impressive number of disorders are associated with dopamine, including movement disorders such as Parkinson's disease and Huntington's disease, psychotic disorders such as schizophrenia, and drug addiction (Fahn et al., 2009; Ng, George, & O'Dowd, 1997).

Drugs Associated with Dopamine Receptors

The best-known of the drugs associated with dopamine receptors are the dopamine receptor antagonists, which include chlorpromazine, clozapine, and haloperidol. If you ever work in the mental health field, you will quickly become familiar with these drugs because they are prescribed to treat schizophrenia and other psychotic conditions. (See Chapter 12 for a full description of schizophrenia and other psychoses.) Because dopamine antagonists are so effective in eliminating many symptoms of schizophrenia, many investigators believe that dysfunction of the dopamine system is the underlying cause of schizophrenia.

Cannabinoid Neurotransmitters

Anandamide was the first neurotransmitter to be identified that binds with cannabinoid receptors in the nervous system. Like the endorphins, the cannabinoid receptor was isolated and identified before anandamide was discovered. These discoveries have been relatively recent. Cannabinoid receptors were first identified in 1988, and anandamide was discovered in the same laboratory at Hebrew University in Israel in 1992 (Devane, Dysarz, Johnson, Melvin, & Howlett, 1988; Devane et al., 1992). The word anandamide is derived from the Sanskrit word for "bliss," ananda, and the suffix -amide refers to its chemical structure. Several other cannabinoid neurotransmitters that bind only with cannabinoid receptors have been discovered since 1992.

Since the discovery of the original cannabinoid receptor, a second cannabinoid receptor has been identified. It now appears that there are two cannabinoid receptors: CB1 and CB2. The CB1 receptor is found primarily in the central nervous system, and the CB2 receptor is found primarily in the peripheral nervous system. The location of cannabinoid receptors in the brain indicates that these receptors probably play a role in emotion, cognition, and motor control (Kowal et al., 2013; Moriarty, McGuire, & Finn, 2011; Terzian, Drago, & Micale, 2011). However, the exact role that cannabinoids and their receptors play is not known.

Drugs Associated with Cannabinoid Receptors

The word cannabinoid comes from Cannabis sativa, a leafy hemp plant that is best-known as marijuana. For centuries, cannabis has been used for both medicinal and recreational purposes. The active ingredient in cannabis, tetrahydrocannabinol (THC), is an agonist that binds to cannabinoid receptors in the brain, producing a number of effects, including changes in mood, thinking, and sensory perception. Moderate cannabis intoxication can impair memory and motor coordination. Other adverse side effects include feelings of depersonalization, panic attacks, and disturbances in thinking that closely resemble a psychosis (Zvolensky, Cougle, & Bernstein, 2010; Zvolensky, Marshall, & Bonn-Miller, 2009).

Nitric Oxide

Nitric oxide was first identified as a neurotransmitter in 1987 when investigators discovered that acetylcholine produces dilation of blood vessels only when nitric oxide is present (Ignarro, Buga, Wood, Byrnes, & Chaudhuri, 1987; Palmer, Ferrige, & Moncada, 1987). Since that time,

neuroscientists have been trying to understand how this gaseous compound functions in the nervous system. You see, nitric oxide presents a bit of a problem to researchers. It is produced by neurons, but it is not released into the synapse like other neurotransmitters (Cooper, Winslow, Govind, & Atwood, 1996 ). In fact, nitric oxide easily diffuses across the cell membrane, which means it can readily leave one neuron and enter another (Garthwaite & Boulton, 1995; Lane & Gross, 1999; Vincent, 2010).

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Psychologists conducting research in this area have found that nitric oxide plays a role in learning and memory and sexual, aggressive, and ingestive behaviors (Forstermann & Sessa, 2011; Ramírez-Bermudez et al., 2010). In addition, decreased nitric oxide levels in the brain result in decreased sexual activity, increased aggression, and decreased eating.

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3.3 The End of the Story: Removing Neurotransmitters from the Synapse

What happens after neurotransmitters have been released into the synapse and bind with postsynaptic receptors? Do they merely stay attached to the receptor forever? Think about what this would mean if the neurotransmitter were to remain bound to the receptor for a long time. A neurotransmitter bound indefinitely to a receptor would produce prolonged depolarization or hyperpolarization—which would have devastating effects on brain function. So, proper brain function requires that neurotransmitters bind rapidly with their respective receptor sites and then just as rapidly detach from the receptor and disappear from the synapse. How is this accomplished?

There are two main mechanisms by which neurotransmitters are removed from the synapse following an action potential: (1) degradation by enzymes and (2) reuptake into the presynaptic neuron.

Degradation by Enzymes

Enzymes are chemical substances that stimulate chemical reactions. The removal of acetylcholine from the synapse is a good example of degradation by enzymes. After its release from the presynaptic terminal, acetylcholine binds briefly with its postsynaptic receptor and then detaches. As it detaches from its receptor and slips back into the synapse, acetylcholine is immediately attacked and deactivated by an enzyme, acetylcholinesterase, that stimulates the chemical process that breaks down acetylcholine (Figure 3.4). Acetylcholinesterase deactivates acetylcholine by breaking the neurotransmitter into two components: acetyl and choline. Thus, acetylcholine is able to stimulate the postsynaptic receptor for only a brief period of time.

In later chapters we will examine how neuropharmacologists have taken advantage of the action of acetylcholinesterase to fashion drugs that prolong or reduce the effect of acetylcholine. Think about it for a moment. A drug that mimics acetylcholinesterase will quickly eliminate acetylcholine from the synapse, thereby reducing acetylcholine's effect. A drug that inhibits acetylcholinesterase (an acetylcholinesterase inhibitor) will hinder the enzyme's action and allow acetylcholine to accumulate in the synapse, prolonging the neurotransmitter's effect. Because acetylcholine plays an important role in memory, a drug that enhances the activity of acetylcholinesterase (and reduces acetylcholine at the synapse) will interfere with memory. In contrast, an acetylcholinesterase inhibitor increases acetylcholine in the synapse and enhances memory (Morley et al., 2010).

Reuptake by the Presynaptic Neuron

Figure 3.4: Acetylcholine

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Unlike acetylcholine, the monoamines are not deactivated by a synaptic enzyme but instead rely on a reuptake mechanism to remove them from the synapse. Hence, they are removed from the synapse much more slowly than acetylcholine. After their release into the synapse following an action potential, monoamines bind briefly with their postsynaptic receptors before detaching and drifting freely in the synapse. A cellular presynaptic transport mechanism, located in the membrane of the axon, pumps the monoamine back inside the presynaptic neuron.

After it is inside the neuron, the monoamine is attacked by a number of enzymes that break it down so it can be removed from the brain and excreted from the body. Two enzymes that have received much study in this regard are monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). MAO breaks down all monoamines, including dopamine, norepinephrine, and serotonin. In contrast, COMT breaks down only the catecholamines dopamine and norepinephrine.

The reuptake and enzymatic mechanisms that remove and deactivate monoamines have provided neuroscientists with important clues about how monoamine levels in the brain can be controlled. Altogether, there are three ways to increase the availability of monoamines in the synapse: (1) increase the release of monoamines into the synapse, (2) block the reuptake transport system that pumps monoamines back into the presynaptic neuron, and (3) inhibit the enzymes, MAO or COMT, that break down monoamines.

The arousing effects of two highly abused drugs, amphetamine and cocaine, are the result of elevated catecholamine levels in the brain. Amphetamine appears to increase catecholamine levels in the synapse by stimulating the release of catecholamines and by blocking the reuptake by the presynaptic neuron. Cocaine increases dopamine levels in the synapse by blocking the dopamine reuptake transport mechanism. In addition, cocaine also blocks the reuptake of the other monoamines, norepinephrine and serotonin.

For nearly half a century, physicians have been prescribing MAO inhibitors to treat patients who are depressed (Healy, 1998). MAO inhibitors block the deactivation of the monoamines by MAO and increase the availability of serotonin, norepinephrine, and dopamine in the brain. Is it possible that low levels of monoamines cause depression? Certainly some investigators think so, and the clinical evidence supports such a suggestion.

Another class of drugs that is used to treat depression is called tricyclic antidepressants. These tricyclic antidepressants are believed to block the reuptake transport systems for norepinephrine, dopamine, and serotonin, elevating monoamine levels in the brain.

In addition, a class of drugs known as selective serotonin reuptake inhibitors (SSRIs) is also prescribed to treat depression in some patients. As their name implies, SSRIs function by inhibiting the serotonin reuptake transport mechanism, thereby increasing serotonin levels in the brain. In contrast, another antidepressant drug, desipramine, blocks the reuptake of norepinephrine but has no effect on the reuptake of serotonin. Table 3.4 summarizes the effects of drugs used to treat depression. There have also been recent experiments involving a drug like ketamine, ADZ6765, in speeding up response to depression through the brain's glutamate system (Sanders, 2013).

Table 3.4: Effects of various antidepressants

Drug Drug effect Norepinephrine Serotonin

Celexa Blocks serotonin reuptake No change Increases

Paxil Blocks serotonin reuptake No change Increases

Prozac Blocks serotonin reuptake No change Increases

Zoloft Blocks serotonin reuptake No change Increases

Elavil Blocks norepinephrine reuptake Increases No change

Norpramin Blocks norepinephrine reuptake Increases No change

Imipramine Blocks serotonin and norepinephrine reuptake Increases Increases

Effexor Blocks serotonin and norepinephrine reuptake Increases Increases

Wellbutrin Weakly blocks serotonin and norepinephrine reuptake Unknown Unknown

Parnate Inhibits monoamine oxidase Increases Increases

Norepinephrine, serotonin, and dopamine seem to play a role in depression, but their exact roles are not clear, as you will learn in Chapter 12 when we return to a consideration of depression. In fact, selecting a drug to treat depression is not always easy (see the "Case Study" box).

Case Study: Choosing the Best Drug to Treat Depression

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iStockphoto/Thinkstock

Photo 3.4 With the proper guidance, medication can be an effective treatment for depression.

Mika was an international student enrolled in an American university when she went to the university's counseling center, complaining of depression. The psychologist who talked to Mika ascertained that she needed medication and referred her to a physician at the university health center for a prescription for an antidepressant. The physician prescribed an SSRI for Mika.

A week later Mika met with her psychologist. She was still depressed, but she now had an additional symptom. She could not stay awake. While the psychologist was talking to her, Mika nodded off and fell asleep repeatedly. The psychologist consulted with the physician who prescribed the SSRI and advised her of Mika's sleepy state. Mika was then taken off the SSRI medication and prescribed a norepinephrine reuptake inhibitor, which eliminated

her sleepiness.

However, Mika's depression did not lift until she'd been taking the new antidepressant for more than 5 weeks. This is typical for antidepressant medications: They sometimes require 4 to 6 weeks before their antidepressant effects become apparent. The reason for this time lag is yet unknown but is probably due to changes that take place within neurons in response to the medication. Many people who are treated pharmacologically for depression get no relief from their symptoms, even after 6 weeks of self-administration of the prescribed drug. Often a different antidepressant medication is prescribed that does improve the patient's mood, but it takes several weeks more before the new medication takes effect.

You've finally come to the end of this chapter on brain chemistry. By now you should have a good idea of how neurons signal to each other with chemicals, and you should understand how the chemicals affect the functioning of neurons. Remember, however, that many neurons communicate with their neighbors using gap junctions or electrical synapses. Chemical synapses are necessary for sending information to cells in other parts of the nervous system. In the next chapter you will learn the names and functions of the various regions of the central and peripheral nervous systems. And you will learn that the neurons in each region have receptors for some types of neurotransmitters but not for others. The entire picture is quite complicated, and even leading experts in the field don't understand all the intricacies. The chapters to come will keep the material as uncomplicated as possible, giving you only information that is relevant for our study of physiological psychology.

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3.4 Chapter Summary Classifying Neurotransmitters

Some neurotransmitters can be classified as amino acids, peptides, monoamines, or cannabinoids, although other neurotransmitters such as acetylcholine and nitric oxide are difficult to group together.

The Roles of Neurotransmitters in Human Behavior

All neurotransmitters bind with several different types of receptors, which indicates that each neurotransmitter can excite or inhibit other neurons in a wide variety of ways.

Acetylcholine

Acetylcholine, the first neurotransmitter to be discovered, initiates contraction of muscles, stimulates parasympathetic responses, and plays a role in learning, memory, and arousal.

Acetylcholine has two types of receptors, nicotinic and muscarinic.

Curare and nicotine are drugs that bind with nicotinic receptors. Muscarine and atropine are drugs that bind with muscarinic receptors.

Amino Acid Neurotransmitters

Amino acid neurotransmitters include glutamate and GABA.

Glutamate typically produces rapid excitation in postsynaptic neurons and is believed to play an important role in the formation of long-term memory. Caffeine and monosodium glutamate are two chemicals associated with glutamate action.

GABA is the most important inhibitory neurotransmitter in the brain. Benzodiazepines, barbiturates, alcohol, and general anesthetics bind to receptor sites in the GABA receptor.

Peptide Neurotransmitters

Nearly 50 different peptide neurotransmitters have been identified, including substance P, cholecystokinin, and endorphins.

Substance P is the neurotransmitter that signals pain.

Cholecystokinin is a hormone that signals satiety following a meal.

Endorphins and other endogenous opiates function to reduce pain and to regulate blood pressure, stress responses, and food intake. Narcotic drugs such as morphine, heroin, codeine, and Demerol bind with endorphin receptors and are effective in alleviating pain.

Monoamine Neurotransmitters

Serotonin, dopamine, norepinephrine, and the hormone epinephrine are the best-known monoamines.

Serotonin regulates mood, sleep, and appetite. Two illicit drugs, lysergic acid diethylamide (LSD) and methylene-dioxymethamphetamine (MDMA, or ecstasy), interact with serotonin receptors.

Norepinephrine is involved in the activation of the sympathetic nervous system and in the regulation of mood and responses to stress. Two drugs, clonidine (a sedative) and yohimbine (an anxiety-producer), bind with adrenergic receptors.

Dopamine has been implicated in motor control, thinking, affect, and hormone secretion. The best-known of the drugs associated with dopamine receptors are dopamine receptor antagonists, which are used to treat schizophrenia and other psychotic conditions.

Cannabinoid Neurotransmitters

Anandamide is a cannabinoid neurotransmitter that binds with cannabinoid receptors in the nervous system and is believed to play a role in emotion, cognition, and motor control.

Marijuana is a drug that also binds with cannabinoid receptors.

Nitric Oxide

Nitric oxide is an atypical neurotransmitter that plays a role in learning and memory, as well as sexual, aggressive, and eating behaviors.

The End of the Story: Removing Neurotransmitters from the Synapse

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There are two main mechanisms by which neurotransmitters are removed from the synapse following an action potential: (1) degradation by enzymes and (2) reuptake into the presynaptic neuron.

Acetylcholinesterase deactivates acetylcholine by breaking the neurotransmitter into two components, acetyl and choline. A drug that inhibits acetylcholinesterase (an acetylcholinesterase inhibitor) will hinder the enzyme's action and allow acetylcholine to accumulate in the synapse, prolonging the neurotransmitter's effect.

The monoamines are not deactivated by a synaptic enzyme but instead rely on a reuptake mechanism to remove them from the synapse. Once inside the neuron, the monoamine is attacked by a number of enzymes that break it down so it can be removed from the brain and excreted from the body. The enzyme, monoamine oxidase (MAO), breaks down serotonin, norepinephrine, and dopamine. Catechol-O-methyltransferase (COMT) deactivates only dopamine and norepinephrine. Amphetamine and cocaine increase catecholamine levels in the synapse by stimulating the release of catecholamines and by blocking the reuptake by the presynaptic neuron.

MAO inhibitors, tricyclic antidepressants, and selective serotonin reuptake inhibitors (SSRIs) have been prescribed to treat patients who are depressed.

Questions for Thought

1. How might an investigator demonstrate that a certain neurotransmitter regulates a particular behavior? For example, how might a psychologist show that cholecystokinin plays a role in eating behavior?

2. When a person becomes addicted to nicotine, what changes take place in the nervous system of the addicted person? What might happen when that person tries to quit smoking?

3. How does nitric oxide differ from other neurotransmitters?

4. Name drugs that increase the activity of receptors associated with acetylcholine, serotonin, dopamine, norepinephrine, anandamide, and endorphins.

Tables of Drug Classes and Effects

Table 3.5: Psychotropic drug classes

Drug class Behavioral effect Neurotransmitter(s) affected

Antidepressants Elevate mood Serotonin, norepinephrine

Antipsychotics (major tranquilizers)

Reduce psychotic symptoms Dopamine (strongly)

Atypical antipsychotics Reduce psychotic symptoms Dopamine (weakly)

Antimanics Stabilize mood Norepinephrine, serotonin, GABA

Sedatives (minor tranquilizers)

Reduce anxiety GABA

Hypnotics Induce sleep GABA

General Anesthetics Produce unconsciousness GABA

Opiates Relieve pain Endorphins

Cannabinoids Stimulate appetite, alter attention Endocannabinoids

Stimulants Increase vigilance, enhance attention, reduce appetite and sleep

Norepinephrine

Table 3.6: Effects of antipsychotic drugs

Drug Drug class Effect on D2 receptor

Amisulpride Atypical Binds loosely (permits normal dopamine action)

Aripiprazole Atypical Binds loosely (permits normal dopamine action)

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Chlorpromazine Classical Binds tightly (inhibits dopamine action)

Clozapine Atypical Binds loosely (permits normal dopamine action)

Flupenthixol Classical Binds tightly (inhibits dopamine action)

Fluphenazine Classical Binds tightly (inhibits dopamine action)

Haloperidol Classical Binds tightly (inhibits dopamine action)

Olanzapine Atypical Binds loosely (permits normal dopamine action)

Pimozide Classical Binds tightly (inhibits dopamine action)

Quetiapine Atypical Binds loosely (permits normal dopamine action)

Remoxipride Atypical Binds loosely (permits normal dopamine action)

Risperidone Atypical Binds loosely (permits normal dopamine action)

Sertindole Atypical Binds loosely (permits normal dopamine action)

Trifluperazine Classical Binds tightly (inhibits dopamine action)

Ziprasidone Atypical Binds loosely (permits normal dopamine action)

Table 3.7: Effects of various antidepressants (Generic names are in italics)

Drug Drug effect Norepinephrine Serotonin

Celexa (citalopram) Blocks serotonin reuptake (serotonin selective reuptake inhibitor)

No change Increases

Luvox (fluvoxamine) Blocks serotonin reuptake (serotonin selective reuptake inhibitor)

No change Increases

Paxil (paroxetine) Blocks serotonin reuptake (serotonin selective reuptake inhibitor)

No change Increases

Prozac (fluoxetine) Blocks serotonin reuptake (serotonin selective reuptake inhibitor)

No change Increases

Zoloft (sertraline) Blocks serotonin reuptake (serotonin selective reuptake inhibitor)

No change Increases

Elavil (amitriptyline) Blocks norepinephrine reuptake Increases No change

Norpramin (desipramine)

Blocks norepinephrine reuptake Increases No change

Tofranil (imipramine) Blocks norepinephrine and serotonin reuptake Increases Increases

Effexor (venlafaxine) Blocks norepinephrine and serotonin reuptake Increases Increases

Wellbutrin (bupropion) Weakly blocks norepinephrine and serotonin reuptake Unknown Unknown

Parnate (tranylcypromine)

Inhibits monoamine oxidase Increases Increases

Table 3.8: Effects of recreational drugs/drugs of abuse

Drug Drug effect Behavioral effect

Alcohol Augments GABA binding to its receptor Increased inhibition, anxiety reduction, and sedation

Amphetamine/Meth/Speed Stimulates norepinephrine release; to a lesser extent, release of dopamine and serotonin

Increased vigilance and focus, reduced fatigue and appetite

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Caffeine Blocks adenosine receptors Inhibits effects of adenosine, produces mild stimulation

Cocaine/crack Blocking the reuptake of dopamine, norepinephrine, and serotonin

Increases mental alertness and produces mild euphoria

Heroin Binds with endorphin receptors; mimics effects of endorphins

Relieves pain, produces euphoria and clouding of mental function

Ketamine Binds with glutamate receptor, antagonizes action of glutamate

Produces dissociative anesthesia

LSD/Acid Binds with serotonin receptors, blocks serotonin action

Produces sensory overload, hallucinations, euphoria

Marijuana Binds to cannabinoid receptors Changes in mood, attention, memory, motor coordination

MDMA/Ecstasy/MDA Stimulates serotonin release and, to a lesser extent, release of norepinephrine and dopamine

Produces mild hallucinations, euphoria

Mescaline Binds with norepinephrine receptors, interferes with action of norepinephrine

Produces mild hallucinations, vivid mental images and distorted vision

Morphine Binds with endorphin receptors; mimics effects of endorphins

Relieves pain, produces euphoria and clouding of mental function

Oxycontin/oxycodone Binds with endorphin receptors; mimics effects of endorphins

Relieves pain, produces euphoria and clouding of mental function

Peyote Binds with norepinephrine receptors, interferes with action of norepinephrine

Produces mild hallucinations, stimulates the visual and visuo-psychic areas of the brain

Psilocybin/Mushrooms Binds with serotonin receptors, stimulates serotonin activity

Produces hallucinations, altered sense of time, and euphoria

Phencyclidine (PCP) Binds with glutamate receptor, antagonizes action of glutamate

Produces dissociative anesthesia

Tobacco/nicotine Binds with nicotinic acetylcholine receptors Produces mixed feelings of relaxation, sharpness, calmness, and alertness

Table 3.9: Review of acetylcholine agonists and antagonists

Type of acetylcholine receptor Example of an agonist Example of an antagonist

Nicotinic Nicotinic Curare

Muscarinic Muscarinic Atropine

Chapter 3 Flashcards

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Web Links

For more information on Botox, search the term on the MedLinePlus website, a service of the U.S. National Library of Medicine. Here you will have access to the latest news, clinical trials, and journal articles related to studies of Botox. http://medlineplus.gov/ (http://medlineplus.gov/)

The National Institute of Drug Abuse's website provides numerous resources and publications for learning about the effects of drugs, including alcohol and other substances, on the brain and, in turn, on human behavior. http://www.drugabuse.gov/ (http://www.drugabuse.gov/)

Key Terms

Click on each key term to see the definition.

acetylcholine (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#)

A neurotransmitter necessary for muscle contraction, memory, and parasympathetic activity.

acetylcholinesterase (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#)

An extracellular enzyme that stimulates the process that deactivates acetylcholine.

agonists (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#)

Chemicals that bind with and activate a receptor.

amino acids (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#)

Relatively simple compounds that contain one NH2 (amino) group and COOH (acid) group.

anandamide (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#)

A neurotransmitter that binds with cannabinoid receptors.

antagonists (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#)

Chemicals that bind with a receptor, blocking the action of the neurotransmitter.

benzodiazepines

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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#)

Minor tranquilizers such as Valium that bind with GABA receptors.

cannabinoid receptors (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#)

Receptors that bind with anandamide and tetrahydrocannabinol, the active ingredient in marijuana.

catechol-O-methyltransferase (COMT) (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#)

An intracellular enzyme that deactivates catecholamines.

cholecystokinin (CCK) (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#)

A peptide released from the duodenum that inhibits eating.

curare (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#)

A nicotinic antagonist that produces paralysis.

dopamine (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#)

A monoamine neurotransmitter that is a precursor of norepinephrine and epinephrine.

endorphin (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#)

An endogenous opiate neurotransmitter that inhibits pain messages.

epinephrine (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#)

A neurohormone, also known as adrenaline, that is released by the adrenal gland and activates the sympathetic nervous system.

gamma-aminobutyric acid (GABA) (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#)

A neurotransmitter that is the most abundant inhibitory neurotransmitter in the brain.

glutamate (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#)

A neurotransmitter that is the most abundant excitatory neurotransmitter in the brain.

hormone (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#)

A chemical released by a gland into the bloodstream.

marijuana (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#)

Cannabis sativa, a leafy hemp plant that has been used for centuries for both medicinal and recreational purposes. The active ingredient in marijuana is tetrahydrocannabinol (THC).

monoamine (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#)

A chemical compound that contains one amino group.

monoamine oxidase (MAO) (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#)

An intracellular enzyme that deactivates monoamines.

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muscarine (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#)

A deadly toxin that comes from a poisonous mushroom.

muscarinic receptor (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#)

A type of acetylcholine receptor in the nervous system that binds with muscarine.

nicotine (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#)

An agonist that binds with acetylcholine nicotinic receptors.

nicotinic receptor (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#)

An acetylcholine receptor that binds with nicotine.

nitric oxide (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#)

An atypical neurotransmitter that readily diffuses across the cell membrane of a neuron.

norepinephrine (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#)

A monoamine neurotransmitter that plays a role in mood, drive reduction, sleep, arousal, cognition, and emotions.

opiates (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#)

Drugs that are derived naturally or synthetically from opium, such as morphine, heroin, codeine, and Demerol.

opioid receptors (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#)

Receptors on the cell membranes of neurons that bind with endogenous opiates and opiate drugs.

peptides (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#)

Short chains of amino acids joined end to end.

psychopharmacology (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#)

The study of chemical substances that affect the activity of neurons.

selective serotonin reuptake inhibitors (SSRIs) (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#)

A class of drugs that is prescribed to treat depression in some patients; SSRIs function by inhibiting the serotonin reuptake transport mechanism, thereby increasing serotonin levels in the brain.

serotonin (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#)

A monoamine neurotransmitter that plays a role in sleep, vigilance, mood, appetite, and repetitive movements.

substance P (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#)

A neurotransmitter used by pain receptors to signal the presence of tissue damage and pain.

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The Organization of the Nervous System

4

Science Photo Library/SuperStock

Learning Objectives

After completing this chapter, you should be able to:

Identify the major functions of the central nervous system.

Explain how the meninges protect the central nervous system.

Compare the functions of the five levels of the spinal cord: cervical, thoracic, lumbar, sacral, and coccygeal.

Draw a rough map of the brain and indicate the location of the hindbrain, midbrain, and forebrain on the map.

Identify the structures in the hindbrain and relate their functions to human behavior.

Discuss the organization of the midbrain.

Describe the differences between the thalamus and the hypothalamus.

Explain the function of the various structures in the limbic system.

Differentiate between the functions of the cerebellum and the basal ganglia.

Name the lobes of the cerebrum and locate each on a drawing of the cerebrum.

Describe the organization of the peripheral nervous system, referring to spinal nerves and cranial nerves.

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On a Saturday night shortly before midnight, 15-year-old Tyler was carried by his worried parents into the emergency room of a large medical center. Tyler was conscious but unable to speak. In addition, he appeared to be paralyzed on the right side of his body. The doctors who examined him were puzzled: Here was a teenager who appeared to have suffered a stroke, a disorder typically associated with older adults. Tyler's symptoms, inability to speak and right-sided paralysis, suggested damage to the left side of his brain.

Although Tyler couldn't speak, he could nod "yes" or shake his head "no" when questioned by the emergency room doctors. At first Tyler refused to answer the doctors' questions. However, he began to cooperate when he was told that the doctors couldn't help him unless he told them what he'd been doing earlier that evening.

The doctors surmised that Tyler had been trying to get high on some type of inhalant. Their questions focused on determining the chemical he had used. It turned out that Tyler and his friends had been sniffing butane, the propellant used in disposable lighters. Butane is known to cause spasms in the muscular walls of blood vessels. In Tyler's case the butane he inhaled caused sudden, extreme constriction of the arteries in his brain, causing a major artery in his left hemisphere to develop a blockage. Neurons in that side of his brain were deprived of oxygen as a result of the blockage and were damaged, producing a loss of function associated with the left hemisphere in the brain.

The World Congress of Neuroscience has hailed the 21st century as the Century of the Brain. The Century of the Brain! How much do you know about the brain? Do you understand the mechanisms by which it controls behavior? If you do, you should be able to explain how brain damage caused by sniffing butane affects behavior. If not, you will be able to explain the effects of brain damage on behavior when you finish this chapter.

This chapter will introduce you to the brain and its organization. As you read this chapter, you will learn about the important structures in the brain and how each participates in the control of bodily functions and behavior. Later in this book, we will look at vital human behaviors such as speech, reasoning, and emotions. We will examine how the brain is involved in mental illness. And we will explore the role of the brain in behaviors that we have in common with other animals, such as eating, sleeping, drinking, and sexual behavior. We will also probe the brain's regulation of movement and sensory processes like vision, taste, smell, touch, and hearing.

Remember from Chapter 2 that the nervous system has two divisions: the central nervous system and the peripheral nervous system. The central nervous system is composed of the brain and the spinal cord. All of the neurons located outside the brain and spinal cord make up the peripheral nervous system. In this chapter we will focus on the organization of the nervous system and, in particular, on the structure of the principal organ of the nervous system, which is the brain. Let's consider the organization of the central nervous system first.

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Flirt/SuperStock

Photo 4.1 Your brain can initiate behavior on its own, prompting the central nervous system to act. An example of this would be thinking of someone and then calling that person.

4.1 An Overview of the Central Nervous System The primary function of the central nervous system is to process information that it receives from the peripheral nervous system and then organize a response to that information. For example, imagine that a spider climbs onto your ankle and begins to walk up your leg. The tickling sensation travels through your peripheral nervous system to your central nervous system. This information travels up your spinal cord to your brain, which then processes the information and sends messages back to your peripheral nervous system, directing your eyes to look at your leg for the source of the tickling and directing your hand to brush the offending creature off your leg.

The brain can also initiate behavior on its own, without prompting from the peripheral nervous system. You might, for example, suddenly think of your sister in a faraway city and decide to telephone her. Your central nervous system in this case directs the movements needed to walk to the telephone, pick up the receiver, and dial your sister's phone number.

Thus, the central nervous has two major functions: (1) to receive and act upon information received from the peripheral nervous system, and (2) to initiate thoughts and behaviors independently without prompting from the peripheral nervous system. As you learned in Chapter 2, information coming from neurons in the peripheral nervous system located below your neck must travel through the spinal cord to be relayed to the brain. Information from neurons in your head and neck is transmitted though the peripheral nervous system directly to the brain.

Protecting the Central Nervous System

The central nervous system is so important to your survival that it is encased in bone for protection. The skull surrounds the brain, and the column of vertebral bones that you know as the backbone protects the spinal cord. Underneath these bones, three layers of tissues, called the meninges, cover the brain and spinal cord, providing further protection (Figure 4.1).

Figure 4.1: The meninges, the protective covering of the central nervous system

The meninges consist of three layers: the dura mater (outer layer), arachnoid (middle layer), and pia mater (innermost layer).

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The outermost layer of the meninges is known as the dura mater. The dura mater is a tough, fibrous protective coating that helps maintain the integrity of the brain and spinal cord. Beneath the dura mater is the arachnoid layer, which gets its name from its spider web–like appearance (arachne means "spider" in Greek). The innermost layer of the meninges is called the pia mater. This delicate tissue is in direct contact with the surface of the brain and spinal cord.

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Southern Illinois University/Science Source

Photo 4.2 In hydrocephalus, a portion of the ventricles is blocked, causing accumulation of cerebrospinal fluid in the brain. Because the bones of the skull are not fixed in very young children, the head of the infant with hydrocephalus will swell as pressure from accumulating cerebrospinal fluid builds. In the newborn infant shown above, light placed behind the head shines through the skull because cerebrospinal fluid has compressed and replaced brain tissue.

The arachnoid layer's web is composed of blood vessels and other vessels containing a special fluid found only in the central nervous system, called cerebrospinal fluid. The word cerebrospinal comes from two words, cerebrum, which is the Latin word for "brain," and spinal, which refers to the spinal cord. Cerebrospinal fluid is manufactured in a structure located near the top of the brain, and it flows down through the brain and spinal cord through a system of canals, called ventricles. When the cerebrospinal fluid reaches the base of the spinal cord, it travels back up the spinal cord through the arachnoid layer of the meninges to the brain.

The ventricles produce nearly a pint of cerebrospinal fluid each day. Blockage of the ventricles causes cerebrospinal fluid to build up in the brain, producing a disorder known as hydrocephalus. You can imagine that, as fluid builds up in the brain due to a blockage of the ventricle system, pressure on neurons in the brain increases, and neurons are damaged or destroyed. Therefore, hydrocephalus is a serious condition that can produce death or permanent damage to the nervous system. We will discuss hydrocephalus in greater detail in Chapter 13.

Scientists have identified several functions of cerebrospinal fluid. First of all, it acts as a watery cushion to protect the central nervous system from smacking against the skull or backbone following a sudden jarring (Johanson et al., 2008; Sakka, Coll, & Chazal, 2011). Cerebrospinal fluid produces a pressure inside the brain that prevents the brain from collapsing like a deflated balloon, and it also plays an important role in brain development (Sakka et al., 2011). Chemicals produced by the brain are transported in the cerebrospinal fluid to the spinal cord. These chemicals found in the cerebrospinal fluid can tell us a lot about the brain (Simonsen, 2012). For example, they can indicate the presence of an infection in the brain or a chemical imbalance.

Cerebrospinal fluid, then, is a window into the brain—it can tell us what is happening in the brain. For example, a number of investigators have linked abnormal levels of serotonin byproducts and GABA found in the cerebrospinal fluid to a greater risk of depression and suicidal behavior (Asberg, 1997; Lee, Petty, & Coccaro, 2009; Loefberg, Agren, Harro, & Oreland, 1998; Raedler, 2011; Singareddy & Balon, 2001). A spinal tap is a medical procedure that is used to extract cerebrospinal fluid from the arachnoid layer of the meninges. This procedure can inform physicians about the state of the brain without their actually going into the brain.

Sometimes bacteria or other microorganisms can invade the meninges, producing a disorder called meningitis. Meningitis is a life-threatening illness that can produce long-term disabilities in those who survive. In meningitis the meninges swell in response to the infection by the microorganism, putting pressure on the spinal cord or brain, which can kill neurons or produce permanent brain damage. The onset of the illness is very rapid. A healthy individual will develop a fever and flu-like symptoms, which rapidly progresses to rigidity of the neck and severe headache. If the infection is left untreated, the individual will lapse into a coma and eventually die. Even with antibiotic treatment, up to as much as 15% of people who contract meningitis may die

(Centers for Disease Control and Prevention, 2012). In the United States meningitis is quite rare, occurring in fewer than 3 out of every 100,000 people each year.

The Spinal Cord

You have already been introduced to the spinal cord in Chapter 2. Recall that, in cross section, the spinal cord resembles a gray butterfly surrounded by a white background (Figure 2.7). The gray "butterfly" is actually composed of neuronal cell bodies, and the white matter is composed of bundles of axons. We see this pattern repeated throughout the nervous system: groups of neuronal cell bodies clustered together forming the gray matter and bundles of axons forming the white matter. In the central nervous system, a cluster of gray matter is called a nucleus (plural is nuclei), and a bundle of axons is called a tract. In the peripheral nervous system, a cluster of gray matter is called a ganglion (plural is ganglia), whereas a bundle of axons is called a nerve.

The spinal cord extends from the base of the skull to the tailbone. It is divided into five sections based on its location within the body: cervical, thoracic, lumbar, sacral, and coccygeal (Figure 4.2). The cervical portion of the spinal cord is located in the neck. As its name implies, the thoracic portion of the spinal cord is the section that runs through the chest area or thorax. The lumbar section is located within the vertebrae that make up the small of the back. The position of "lumbar support" in the driver's seat of your car corresponds with the location of the lumbar area of the spinal cord. The sacral portion of the spinal cord is found within the backbones that are attached to the pelvic girdle, the circle of bones that make up your hips and pelvis. The coccygeal portion, which is located at the very base of the spinal cord, is very small and virtually useless in humans.

Figure 4.2: The five segments of the spinal cord Each of the five segments receives messages from and controls different parts of the body. Which parts of the body does the sacral section command?

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Each of the five segments of the spinal cord receives information from and controls the muscles and organs in a particular part of the body. The cervical portion of the spinal cord innervates the shoulders, arms, and hands. The thoracic portion of the spinal cord regulates the functioning of muscles and organs in the chest and upper abdomen. The lower abdominal muscles and organs, as well as muscles in the legs and feet, are controlled by the lumbar portion of the spinal cord. Finally, the sacral portion of the spinal cord directs the workings of the organs within the pelvis, including the reproductive organs, the bladder, and rectum. In an animal with a tail, the coccygeal region of the spinal cord controls tail movements and receives sensory information from the tail. In humans, the coccygeal spinal cord controls only a small group of muscles above the anus.

Spina bifida is a disorder in which the bony spinal column fails to close properly during development, leaving a part of the spinal cord exposed. The amount of exposed spinal cord varies, depending on the extent of the opening in the backbone. Approximately 1 out of every 1,000 children born has spina bifida, although the disorder can be detected early in pregnancy. Because the spinal cord protrudes out of the backbone in spina bifida, it is vulnerable to infection and damage, which can leave the afflicted child severely physically and sometimes mentally challenged. Surgical treatment, including closure of the bony defect, can sometimes help children born with this disorder. This surgical treatment can be performed prenatally (while the fetus is still in the uterus) or postnatally (after birth). Recently, a team of investigators demonstrated that prenatal surgery is more effective than postnatal surgery in reducing motor and mental impairment in children with spina bifida (Adzick et al., 2011).

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Scott Camazine/Science Source

Photo 4.3 This MRI scan of a normal brain highlights the different areas of the brain and its structures.

4.2 The Brain I remember the first time I saw an MRI scan of my own brain. I was fascinated and, at the same time, disappointed to find that my brain looked just like any other healthy human brain I'd ever seen. See the following image for an example of a typical brain. I'm sure my brain looks just like your brain. Most of us have virtually identical structures situated in the same locations within the skull.

Furthermore, our human brains bear a close resemblance to the brains of other mammals (Figure 4.3). In fact, if you are really observant, you will notice many similarities between your brain and the brains of other vertebrates, like fish, cats, and birds. For all vertebrates, the brain can be divided into three parts: the forebrain, the midbrain, and the hindbrain. These terms make a lot of sense if you consider the brain of a typical animal, one that is oriented horizontally with respect to the ground. The hindbrain is located in the back of the brain toward the animal's hindquarters. The forebrain is situated in the front of the brain, and the midbrain is situated in the middle.

Figure 4.3: Comparison of the human brain with the brains of other creatures

Homo sapiens may not see, hear, or smell as well as many other species, but greater relative brain size and the greater relative size of the "thinking" part—the association cortex—of the human brain—have given us an evolutionary advantage.

Source: Copyright Hungry Coyote Limited. Used by permission.

In humans and other animals that have a vertical orientation, the hindbrain is located at the bottom, the midbrain is located on top of the hindbrain, and the forebrain, which is enormous in humans, sits on top, covering not only the tiny midbrain but also the larger hindbrain. Figure 4.4 shows the positions of the forebrain, midbrain, and hindbrain in the human brain.

Figure 4.4: The forebrain, midbrain, and hindbrain This figure shows the development of the forebrain, midbrain, and hindbrain

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as one ages. What changes do you see?

The Hindbrain

Three structures make up the hindbrain: the medulla, the pons, and the cerebellum (Figure 4.5). The medulla is located directly above, or superior to, the spinal cord. This means that all information coming from and going to the spinal cord must pass through the medulla. Indeed, the medulla contains a great deal of white matter containing tracts that relay information between the spinal cord and higher brain areas. Gray matter is also found in the medulla, however. Clusters of neurons, known as nuclei, are scattered throughout the medulla. Each nucleus has a specific function, as you will learn in later chapters. Some nuclei regulate life-support functions, such as breathing, coughing, or vomiting. Damage to these nuclei can result in death. Other nuclei in the medulla receive sensory information or send motor commands to muscles in the head, neck, and trunk.

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Located directly above the medulla is the pons. The word pons means "bridge" in Latin. The pons is a bridge-like structure that is composed almost entirely of white matter, or tracts, conveying information between the higher brain regions and the medulla and spinal cord. Information leaving your forebrain travels down tracts through your midbrain to your hindbrain and spinal cord, passing through the pons. Neural messages coming from the medulla and spinal cord pass through the pons before traveling to higher brain areas, as you will learn in later chapters.

The cerebellum lies dorsal to both the medulla and the pons. We will discuss its structure in greater detail in Chapter 5. For now, you should know that it is divided into two hemispheres: right and left. Each hemisphere contains a cerebellar cortex (gray matter) and underlying white matter. This architecture (gray matter situated over tracts of white matter) gives the cerebellum a characteristic tree-like appearance when it is viewed in cross section.

The neurons in the cerebellum are responsible for coordinating muscular activities, especially those involved in rapid and repetitive movements. Alcohol is known to especially impair the functioning of the cerebellum, causing intoxicated persons to lose their muscle coordination. Sobriety tests performed by police officers are designed to detect impairment of the cerebellum (see the "For Further Thought" box in this chapter).

For Further Thought: Sobriety Tests—Evaluating Cerebellar Impairment

Alex was in Atlanta for a professional conference, where he had the opportunity to meet with colleagues and former college friends. The first night of the conference, he went out to a bar with a group of friends. After a fun evening of swapping industry stories, Alex left the bar around midnight with four friends. He had drunk six beers but felt that he could drive safely. Within minutes, he was stopped at a roadblock by police who were looking for drunk drivers.

Alcohol affects the functioning of neurons throughout the brain, including the cerebellum. Because the cerebellum controls coordinated movements, alcohol interferes with coordination. A sobriety test allows police officers to check for signs of cerebellar dysfunction that are caused by alcohol intoxication. A police officer approached Alex's car and asked for his driver's license. Nervously, Alex fumbled in his wallet for his license. The officer scanned it briefly, and then asked Alex to say the alphabet as quickly as he could. Alex did well until he got to "L, M, N, O, P." Because he was intoxicated, his tongue stumbled over those letters.

The police officer asked Alex to get out of the car and walk along a straight line that was painted on the pavement. Alex had a difficult

Figure 4.5: Major structures in the brain

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Charlie Neuman/ZUMA Press/Corbis

Photo 4.4 Alcohol's influence on the cerebellum causes a loss of coordination.

time walking the line. He staggered, weaving from side to side, and nearly fell over at one point. Finally, the officer told Alex to close his eyes, extend his right arm, and then touch his nose with his right index finger. Alex closed his eyes and tried to touch his nose, but he slammed his hand into his face very hard. Alex failed all three phases of the sobriety test. He demonstrated fine motor impairment when he slipped up saying the letters of the alphabet. Impairment of gross movement was evident when Alex could not walk along a straight line. In addition, Alex failed the finger-to-nose test, a test that assesses the ability of the cerebellum to locate the position of a particular limb in space and to direct the movement of that limb based on its location.

After Alex failed the sobriety test, he was subjected to a Breathalyzer test, which measures alcohol content of the expired breath. This test indicated that the level of alcohol in Alex's body was above the legal limit. Alex was given a ticket for DUI and taken to jail. His car was towed away, and his intoxicated friends had to take a taxi home.

The Midbrain

The midbrain is the smallest of the three major divisions of the brain. In the human brain, it is roughly the size of a large acorn. The midbrain can be divided into three parts: the dorsal portion, the ventral portion, and the tegmentum, which lies between the dorsal and ventral areas. The dorsal area is also known as the tectum, and it contains four structures that look like little hills, the superior colliculi and the inferior colliculi. (The term colliculi means "little hills" in Latin.) You have two superior colliculi and two inferior colliculi in your midbrain: one of each on the left side of your brain and one of each on the right side. Located above the inferior colliculi, the superior colliculi are important in processing visual information, as you will learn in Chapter 6. The inferior colliculi are involved in relaying auditory information to the cerebellum and forebrain.

The tegmentum contains a number of important structures, such as the red nucleus, the periaqueductal gray, and the substantia nigra, that we will cover later in this book, structures that play a vital role in movement, attention, pain control, emotions, and sensory processing. For the most part, the ventral area of the midbrain consists of tracts relaying neural information between the hindbrain and the forebrain.

The reticular formation, which runs from the hindbrain to the forebrain, takes up a large portion of the midbrain. The reticular formation plays an important role in keeping you awake and alert. When your alarm goes off, it is your reticular formation that rouses you to consciousness. The reticular formation also arouses you when someone calls your name, when some creepy-crawlie slithers up your arm, or when someone yells "Help!" Damage to the reticular formation can produce a state of unconsciousness called a coma, in which a person is unable to respond to external stimuli.

The Forebrain

The largest part of the human brain is the forebrain (Figure 4.4). This area of the brain produces the most interesting human behaviors, such as thinking, creating, eating, speaking, and emoting. The forebrain contains a number of important structures, including the cerebrum, basal ganglia, limbic system, thalamus, and hypothalamus. Two forebrain structures, the thalamus and hypothalamus, make up the diencephalon, which gets its name from the Greek words for "two" (dio) and "brain" (encephalon). Let's examine each of these forebrain structures, beginning with the diencephalon.

The Diencephalon

The diencephalon is located directly above the midbrain. Information from the midbrain must pass through the diencephalon in order to reach the higher parts of the forebrain. The prefix hypo- means "under" in Greek. As its prefix hypo- implies, the hypothalamus lies under the thalamus (Figure 4.5).

The shape of the thalamus resembles an egg that has been flattened on one side. It is composed of a large number of nuclei, or clusters of neurons, that relay information to and from structures in the forebrain, especially the largest structure, which is called the cerebrum. The cerebrum is considered the seat of consciousness by most behavioral neuroscientists. That is, you do not become consciously aware of a stimulus unless neural information about the stimulus makes its way to the cerebrum. It is the function of the nuclei in the thalamus to process incoming information and pass it on to the cerebrum. Thus, the thalamus acts like a switchboard operator relaying information between the cerebrum and other parts of the brain. There is evidence that the thalamus also receives information from the cerebrum and plays an important role in attention (Haber & Calzavara, 2009; McAlonan, Cavanaugh, & Wurtz, 2006; Sillito, Jones, Gerstein, & West, 1994; Zikopoulos & Barbas, 2006).

The hypothalamus is located on the ventral surface of the brain superior to the midbrain (Figure 4.5). Below or ventral to the hypothalamus lies the pituitary gland, which is attached to the hypothalamus by a stalk. The hypothalamus directly controls the activity of the pituitary gland by releasing hormones that are sent to the pituitary gland. Hormones are specialized chemicals that are released by one structure in the body, typically called a

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Photo 4.5 The amygdala has two separate regions: one that produces fear and escape behaviors and one that produces aggressive behavior when attacked.

Neurosurgeon Joe Bogen discusses the relationship between the corpus collosum and the two hemispheres of the brain. What implications are

Splitting the Brain

gland, and affect another structure in the body. The hypothalamus directs the activity of the pituitary gland with hormones, and the pituitary gland uses hormones to control the activity of other glands and organs in the body, as you will learn in Chapters 8 through 11.

In addition, the hypothalamus is involved in the regulation of many motivated behaviors, such as eating, drinking, sleeping, temperature control, sexual behavior, and emotions. Like the thalamus, the hypothalamus contains many tiny clusters of neurons called nuclei. Each nucleus in the hypothalamus plays a role in the regulation of a specific motivated behavior. We will examine the functions of the hypothalamus in Chapters 8 through 11.

The diencephalon, together with the midbrain and hindbrain, makes up the brain stem. In terms of evolutionary development, the brain stem is considered to be the oldest part of the brain. If you examine the brain of a reptile, like that of a snake or a turtle, you would find that the reptilian brain is very similar to the human brain stem.

The Limbic System

The hippocampus, amygdala, and septum, together with a handful of regions in the midbrain, diencephalon, and cerebrum, make up the limbic system. The Canadian psychologist Paul MacLean coined the term limbic system. Limbic comes from the Latin word limbus, meaning "boundary." To MacLean's mind, the limbic system formed a boundary between the brain stem and the higher centers of the brain. The limbic system functions in the production and experience of emotion.

The hippocampus gets its name from its seahorse-like shape (hippo means "horse" and kampus means "sea monster" in Greek). In addition to the role it plays in emotions, the hippocampus is responsible for some types of learning and for the creation of permanent, or long-term, memories. Damage to the hippocampus can interfere with and produce memory loss.

The amygdala is located at the tail end of the hippocampus's seahorse shape. It is oval in appearance and has two distinct regions: one that produces fear and escape behaviors when stimulated and another that elicits rage and aggressive attack behavior when activated.

Rabies, which is caused by a virus that attacks the forebrain, especially in the region of the amygdala, produces a lack of natural fear, as well as vicious attack behavior, in rabid animals.

The septum is a complex forebrain structure that contains a number of different nuclei with diverse functions. Until 1954 the function of the septum was unknown. Studies by James Olds and Peter Milner in the early 1950s demonstrated that rats will eagerly press a bar to receive brain stimulation of the septum (Olds & Milner, 1954). Thus, the septum is known as the "reward center" of the brain and is involved in the development of addictions (Luo, Tahsili-Fahadan, Wise, Lupica, & Aston-Jones, 2011). In addition, recent research has also implicated the septum in the development of intense romantic love (Acevedo, Aron, Fisher, & Brown, 2011; Fisher, Aron, & Brown, 2005).

The Basal Ganglia

The basal ganglia consist of several clusters of neurons found in the base of the forebrain. Together, these structures are responsible for the production of movement. For example, you notice that your hands are dirty and decide to wash your hands. The basal ganglia initiate this washing behavior. Hand-washing compulsions, in which people feel compelled to wash their hands hundreds of times a day, are a common manifestation of obsessive-compulsive disorder. Research has demonstrated that faulty circuits between the basal ganglia and other brain structures may cause obsessive-compulsive disorders (Correia et al., 2010). The basal ganglia have also been implicated in a number of movement disorders, such as tremors associated with Parkinson's disease and Huntington's chorea (Lieu & Subramanian, 2012), as you will learn in Chapter 5.

The Cerebrum

The cerebrum (cerebrum means "brain" in Latin) gets its name from the fact that it is by far the largest structure in the brain—so large, in fact, that when the skull is removed from the top of a person's head, the only structure that can be seen is the cerebrum (Figure 4.6). The rest of the forebrain, the midbrain, and the hindbrain are tucked underneath the cerebrum in the skull. This means that damage to the skull, as in a skull fracture, will have its greatest impact on the cerebrum. In Chapter 13 we will look at different effects of damage to the cerebrum.

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presented by splitting the brain?

Figure 4.6: The cerebrum in two views: in the skull and removed from the skull

Each lobe of the cerebrum has a specialized function in the brain, such as speech, hearing, and sight.

The cerebrum is organized like the cerebellum, with a cortical layer called the cerebral cortex, which consists of a thin layer of gray matter (less than 2 millimeters in thickness) and white matter beneath the cortex. The white matter is composed of axons leaving and entering the cerebral cortex. Some axons carry information from nuclei in the thalamus to particular regions of the cortex. Other axons carry information from the cerebral cortex to specific nuclei in the thalamus. Most axons in the white matter of the cerebrum, however, carry information from one area of the cortex to another.

The cerebrum has two halves, called cerebral hemispheres. That is, you have a left cerebral hemisphere and a right cerebral hemisphere. Four lobes make up each cerebral hemisphere: the frontal lobe, the parietal lobe, the temporal lobe, and the occipital lobe (Figure 4.6). Although each lobe has specialized functions, the four lobes in each hemisphere communicate with each other and with the lobes in the other hemisphere. Communication between the hemispheres is made possible by the corpus callosum (Figure 4.7). The corpus callosum is a large, thick tract that connects neurons in the left and right cerebral hemispheres.

Figure 4.7: The cerebrum in cross section In this image the cerebrum is seen in two views in cross section: mid-sagittal cross section (left) and coronal cross section (right).

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The Frontal Lobes

Brain investigators divide the frontal lobe into three separate regions, each with its own special functions: the motor cortex, the premotor cortex, and the prefrontal cortex. The motor cortex directs fine motor coordination. The neurons in the motor communicate directly with the motor neurons that control muscle contractions. Located immediately anterior to (or in front of) the motor cortex, the premotor cortex processes information about intended movements and sends that information on to the motor cortex.

The prefrontal cortex contains a number of regions that have been demonstrated to control a number of executive functions, including short-term memory, working memory, decision making, and prioritizing behaviors. When you are trying to decide whether you should do your laundry, watch television, or call your mother, it is your prefrontal cortex that weighs the alternatives and empowers you to make a decision. Throughout this book, we will make many references to the frontal lobe because it plays an important role in who you are and what you do.

The Parietal Lobes

Located directly posterior to the frontal lobes, the parietal lobes consist of the primary somatosensory cortex and the secondary somatosensory cortex. The prefix somato- is derived from the Latin word soma, which means body. Somatosensation refers to sensations that arise from the body. The principal function of the parietal lobes, then, is to process sensory information coming in from the body, whether it be a stomachache or the sensation of someone stroking your arm or cold toes on a wintry day. You will learn more about the parietal lobe in Chapter 6.

The Occipital Lobes

The occipital lobes are situated at the posterior end of the cerebrum, behind the parietal lobes. The principal function of the occipital lobes is to process visual information coming from the eyes. As you will learn in Chapter 6, neurons in the occipital lobe receive information about the images detected by the eyes, analyze that information by breaking each image into tiny components, and then reconstitute the image after communicating with neurons in the frontal, parietal, and temporal lobes.

The Temporal Lobes

The temporal lobes play a role in a number of important functions. The senses of taste, smell, and audition are processed in the temporal lobes. Language comprehension, too, is regulated in the temporal lobe, as is recognition of visual objects and faces. In addition, several structures, including the amygdala and the hippocampus, are located deep beneath the cortex of the temporal lobe. Therefore, damage to the temporal lobe can affect hearing, taste, smell, comprehension of language and facial expressions, mood, and memory.

Left or Right?

Recall that the cerebrum comprises two cerebral hemispheres that are connected by a band of white matter called the corpus callosum. Psychologists such as Nobel Prize winner Roger Sperry have demonstrated that the left and right cerebral hemispheres have specialized functions, too. The new brain-scanning technologies have confirmed that the cerebrum divides its work asymmetrically across the two hemispheres. For most people the left hemisphere plays an important role in speech and language comprehension. Arithmetic and scientific reasoning also appear to be controlled by the left hemisphere. In contrast, neurons in the right hemisphere process information about emotional expression, face recognition, music, and other time-space relationships. However, it is important to remember that the differences between the left and right hemispheres are not clear-cut. Research has suggested that some people lack specialized hemispheric skills (Gazzaniga, 1989; Schambra et al., 2011).

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4.3 The Peripheral Nervous System Recall from Chapter 2 that the peripheral nervous system has two divisions: the somatic nervous system and the autonomic nervous system. The somatic nervous system innervates striated muscles, which are under your voluntary control. In contrast, the autonomic nervous system innervates smooth muscles (and cardiac, or heart, muscles) and is not under your conscious control. The autonomic nervous system acts automatically, in response to signals from the central nervous system.

The autonomic nervous system is composed of two divisions: the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system becomes activated when a person is excited, aroused, or in another highly emotional state. On the other hand, the parasympathetic nervous system plays an energy-conserving role and is associated with a relaxed, vegetative state.

Both the sympathetic and parasympathetic nervous systems innervate all organs and body structures containing smooth muscles. However, the two divisions of the autonomic nervous system have opposite effects on the structures that they stimulate. For example, recall from Chapter 2 that the sympathetic nervous system speeds up the heart, and the parasympathetic system slows it down. Sympathetic activation causes the pupils in the eyes to dilate, and parasympathetic activation causes the pupils to constrict. Likewise, when the sympathetic nervous system is activated, salivary glands produce a thick saliva in small quantities, whereas parasympathetic stimulation of the salivary glands causes copious secretion of a thin, watery saliva.

The word innervate is used several times in the preceding paragraphs. Notice that the root of innervate is nerve. The peripheral nervous system transmits information over relatively long distances in the body by way of nerves. To innervate, then, means to send information by way of nerves. Usually this information serves to control or regulate the body structure that is innervated.

The peripheral nervous system transmits information to the entire body by way of 12 pairs of cranial nerves and 31 pairs of spinal nerves, or 43 pairs of nerves altogether. They are described as "pairs of nerves" because nerves exit from the right and left halves of the brain and spinal cord. That means that you have a left optic nerve that connects your left eye to your brain and a right optic nerve that connects your right eye. The same is true for all the nerves that we will discuss in this section. Each nerve is paired with a nerve on the opposite side of the body. Let's consider the cranial nerves first.

Cranial Nerves

The cranial nerves permit direct communication between the brain and the peripheral nervous system. Cranial nerves allow for (1) sensory input from the head, neck, and upper abdomen to the brain; (2) motor output from the brain to the skeletal muscles in the head and neck; and (3) parasympathetic output to smooth muscles in the head, neck, and upper abdomen. These nerves gain access to the brain via holes in the skull. Table 4.1 summarizes the functions of the twelve cranial nerves. Note that Roman numerals are used to denote each cranial nerve.

Table 4.1: Functions of the cranial nerves

Cranial nerve Function

Olfactory (I) Sensory: smell

Optic (II) Sensory: vision

Oculomotor (III) Motor: eye muscles

Trochlear (IV) Motor: eye muscles

Trigeminal (V) Sensory: skin of face, jaws, teeth Motor: muscles that close mouth

Abducens (VI) Sensory: eye muscles Motor: eye muscles

Facial (VII) Sensory: taste, facial muscles Motor: muscles of facial expression

Auditory (VIII) Sensory: hearing, vestibular senses

Glossopharyngeal (IX) Sensory: tongue, throat Motor: muscles of tongue and throat

Vagus (X) Sensory: taste, organs of chest and upper abdomen Motor: smooth muscles in neck, chest, upper abdomen

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Accessory (XI) Motor: skeletal muscles of neck

Hypoglossal (XII) Motor: muscles in lower jaw, tongue

Spinal Nerves

In addition to the cranial nerves, the peripheral nervous system contains 31 pairs of spinal nerves. The spinal nerves are bundles of axons that exit and enter the spinal cord. Recall from our earlier discussion of the spinal cord that axons entering the dorsal aspect of the spinal cord are carrying sensory information and that axons leaving the ventral aspect of the spinal cord are carrying motor information to muscles. Each spinal nerve, then, is composed of a sensory branch and a motor branch (Figure 4.8). All spinal nerves are paired, with one nerve associated with the left side of the spinal cord and one nerve associated with the right side.

Figure 4.8: The sensory and motor branches of spinal nerves

Sensory nerves enter the dorsal aspect of the spinal cord. Motor nerves exit from the ventral aspect of the spinal cord.

You have already learned that the spinal cord is divided into five regions: cervical, thoracic, lumbar, sacral, and coccygeal. The spinal nerves are named after the region of the spinal cord from which they arise. Because the spinal cord is encased within the vertebral column, the spinal nerves can enter and exit the spinal cord only where there are breaks in the column of bones that make up your backbone (Figure 4.9). Therefore, the number of nerves that arise from each region of the spinal cord is determined by the number of vertebral bones that cover and protect that region.

Figure 4.9: Spinal nerves exiting between vertebrae

The number of nerves between your vertebrae is determined by the number of vertebral bones that shield that particular region.

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Go back to Figure 4.2. Here you can see that 8 pairs of nerves arise from the cervical region of the spinal cord, 12 pairs of nerves arise from the thoracic region, 5 pairs of nerves from the lumbar region, 5 pairs of nerves from the sacral region, and 1 pair of nerves from the coccygeal region, for a grand total of 31 pairs of nerves.

Each spinal nerve is named after the region of the spinal cord from which it arises. A nerve from the cervical region is named C1 through C8, depending on where it arises, with C1 being the most superior cervical nerve and C8 the most inferior of the cervical nerves. Thoracic nerves are named T1 through T12, with T1 being most superior and T12 most inferior. Likewise, lumbar nerves are named L1, L2, L3, L4, and L5, and sacral nerves are named S1, S2, S3, S4, and S5. Each spinal nerve innervates a specific area of the body. The body area innervated by one spinal nerve is called a dermatome. Figure 4.10 illustrates the dermatomes associated with each spinal nerve.

Figure 4.10: Dermatomes Spinal nerves innervate specific areas of the body: C1–C8 (cervical nerves), T1–T12 (thoracic nerves), L1–L5 (lumbar nerves), and S1–S5 (sacral nerves).

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When a person suffers an injury to the spinal cord, we identify the injury by its location on the spinal cord. If a woman breaks her neck between the third and fourth cervical vertebrae, we say that she has a C4 injury. In general, the higher the lesion on the spinal cord, the more impairment of movement and sensation we expect to see. A person with a C4 injury, or an injury to the spinal cord above C4, is likely to develop quadriplegia, a disability in which the motor and sensory functions of all four limbs are impaired. If you look closely at Figure 4.10, you will see that the hands and forearms receive innervation from C6, C7, and C8. This means that some arm function may be spared with a C5 injury, and the person with a C4 injury will have weak or limited motor control of the forearms.

The Organization of the Peripheral Nervous System

This final section will help you gain an understanding of how the peripheral nervous system is distributed across the cranial and spinal nerves. So far, you've learned that the peripheral nervous system comprises 12 cranial nerves and 31 spinal nerves. You've also learned that the peripheral nervous system has two divisions: the somatic and autonomic nervous systems, and you've learned that the autonomic nervous system is further divided into the sympathetic and parasympathetic nervous systems.

Except for cranial nerves I, II, and VIII, all cranial and spinal nerves innervate skeletal muscles and, thus, are part of the somatic nervous system. (Recall that cranial nerves I, II, and VIII carry sensory information only and have no motor component.) Not all cranial and spinal nerves innervate smooth muscles, however. Therefore, the autonomic nervous system is not distributed across all nerves. Of the cranial nerves, only cranial nerves III, V, VII, IX, and X innervate smooth muscles (Figure 4.11). Similarly, only the spinal nerves arising from the thoracic, lumbar, and sacral regions of the spinal cord relay information from the autonomic nervous system.

The two divisions of the autonomic nervous system, the sympathetic and the parasympathetic nervous systems, are also distributed unevenly across the spinal and cranial nerves. The sympathetic nervous system arises from the thoracic and lumbar regions of the spinal cord. Thus, only the thoracic and lumbar nerves carry sympathetic information. Messages from the sympathetic nervous system are sent to various organs and glands throughout the body, preparing the body to deal with arousing or stressful stimuli. The "Case Study" describes the case of a young boy with cancer of the sympathetic nervous system.

Figure 4.11: Distribution of the autonomic nervous system

The sympathetic nervous system arises from the thoracic and lumbar regions of the spinal cord. The parasympathetic nervous system arises from the sacral region of the spinal cord and from the brain (via cranial nerves).

Case Study: Neuroblastoma

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Photo 4.6 Neuroblastoma is a form of cancer that strikes the neurons of the sympathetic nervous system. Shown is a microscopic view of neuroblastoma cells.

Robyn was a happy, friendly baby who had big blue eyes and a ready smile. Soon after he first learned to walk, Robyn began to complain of pain in his back. He would take a few steps, grab his sides, and groan. When he started to talk, his first words included "Ow!" and "Hurt!"

Robyn's mother took Robyn to his pediatrician, the first of many physicians who examined Robyn. The pediatrician was doubtful that Robyn was really experiencing pain and suggested that he was just calling for more attention. However, Robyn continued to complain about pain in his back, especially when he walked. His mother had him examined by two other pediatricians who could not find anything wrong.

When Robyn was 3 years old, his mother took him to a family practitioner who referred him to a physician who specialized in the treatment of arthritis. The arthritis specialist examined Robyn carefully before he said to Robyn's mother, "Your son does not have arthritis. He has neuroblastoma."

Neuroblastoma is a form of cancer that strikes the neurons of the sympathetic nervous system. Tumors were found in the thoracic and lumbar areas of Robyn's back, a common origin of neuroblastoma. That explained why Robyn experienced pain in the middle of his back. Over time, tumors spread along the entire distribution of Robyn's sympathetic nervous system, to his lungs, liver, and other organs. Tumors developed even in Robyn's eyes, blinding him. A cheerful little boy until the end, Robyn died shortly before his fifth birthday.

The sympathetic nervous system is sometimes referred to as the thoracolumbar system because it arises from the thoracic and lumbar regions of the spinal cord. Similarly, the parasympathetic nervous system is called the craniosacral system because only certain cranial nerves and nerves from the sacral region of the spinal cord relay parasympathetic information to smooth muscles and organs. Cranial nerves III, V, VII, IX, and X conduct information in the parasympathetic nervous system to smooth muscles and glands in the head and neck. In addition, cranial nerve X carries parasympathetic stimulation to smooth muscles and organs in the chest and upper abdomen, such as the heart and the stomach. Sacral nerves relay parasympathetic stimulation to the smooth muscles and organs of the lower abdomen and pelvic area.

We will come back to a discussion of the autonomic nervous system many times during the course of this book, when we are examining eating behavior, sexual behavior, emotion, and the reaction to stress. Autonomic arousal, especially activation of the sympathetic nervous system, can also affect perception, attention, learning, and a number of cognitive processes. Therefore, it is important that you understand thoroughly the differences between the two divisions of the autonomic nervous system, the sympathetic and parasympathetic nervous systems.

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4.4 Chapter Summary An Overview of the Central Nervous System

The central nervous system is composed of the brain and spinal cord.

The central nervous has two major functions: (1) to receive and act upon information received from the peripheral nervous system and (2) to initiate thoughts and behaviors independently without prompting from the peripheral nervous system.

Protecting the Central Nervous System

The central nervous system is protected by bone and the meninges, which has three layers.

The outermost layer of the meninges is the dura mater, the middle layer is the arachnoid layer, and the innermost layer is the pia mater.

Vessels in the arachnoid layer contain a fluid found only in the central nervous system called cerebrospinal fluid.

The Spinal Cord

The spinal cord is divided into five sections: cervical, thoracic, lumbar, sacral, and coccygeal, each of which controls the muscles and organs in a specific area of the body.

The Brain

The brain has three subdivisions: the hindbrain, the midbrain, and the forebrain.

The Hindbrain

The medulla, pons, and cerebellum are the major structures in the hindbrain.

Neurons in the medulla regulate life-support functions, receive sensory information, or send motor commands to muscles in the head, neck, and trunk.

The pons permits passage of information between the spinal cord and higher regions of the brain.

The cerebellum coordinates muscular activity and is especially vulnerable to alcohol, which impairs its functioning.

The Midbrain

In the midbrain are located the superior and inferior colliculi, the tegmentum, and the reticular formation.

The superior colliculus processes visual information, and the inferior colliculus processes auditory information.

The reticular formation runs from the hindbrain to the forebrain via the midbrain and plays an important role in keeping the individual awake and alert.

The Forebrain

The forebrain is the largest part of the human brain.

The forebrain contains the diencephalon, the basal ganglia, the limbic system, and the cerebrum.

The Diencephalon

The diencephalon is composed of the thalamus and hypothalamus.

The thalamus contains a cluster of nuclei that relay information to and from the cerebrum.

The hypothalamus is involved in the regulation of the pituitary gland and motivates behaviors such as sleeping, eating, and drinking.

Together, the midbrain, hindbrain, and diencephalon make up the brain stem, which regulates our most primitive behaviors, such as breathing, sleep, sexual behavior, drinking, and eating.

The limbic system produces emotional behavior and contains the hippocampus, amygdala, and septum.

The hippocampus is a seahorse-shaped structure that plays a role in emotion as well as the creation of long-term memories.

The amygdala is involved in emotional behaviors such as fear, escape, rage, and aggression.

The basal ganglia are composed of clusters of neurons located in the base of the forebrain and play a role in the production of movement.

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The cerebrum is the largest structure in the brain and is organized like the cerebellum with two hemispheres, a cortical layer (the cerebral cortex, which contains the cell bodies of hundreds of millions of neurons) and underlying white matter.

Mental activities requiring consciousness are processed in the four lobes of the cerebrum.

The frontal lobes consist of three regions: the motor cortex, the premotor cortex, and the prefrontal cortex. Processing of somatosensation is one of the principal functions of the parietal lobes, and processing of vision is the principal function of the occipital lobes. The temporal lobes are involved in a number of functions, including hearing, taste, smell, and emotions.

The Peripheral Nervous System

The peripheral nervous system is composed of 12 cranial and 31 spinal nerves.

The Cranial Nerves

Cranial nerves allow for direct communication between the brain and the peripheral nervous system.

The Spinal Nerves

Spinal nerves are named after the five regions of the spinal cord: cervical, thoracic, lumbar, sacral, and coccygeal.

The body region innervated by one spinal nerve is called a dermatome.

Questions for Thought

1. Which parts of the brain are highly developed in alligators? In birds? How did you reach your conclusion?

2. How do you think the limbic system influences the functioning of the cerebrum?

3. How does the function of the cerebellum differ from that of the basal ganglia?

Chapter 4 Flashcards

Web Links

To put brain development into context, search "Adolescent Brain Development" on the U.S. Department of Health & Human Services' website. Here you will learn about the factors that contribute to brain development in adolescents and the effects on teenage behavior, including decision-making and risk-taking. http://www.hhs.gov/ (http://www.hhs.gov/)

To learn more about disorders that affect the peripheral nervous system, visit the MedlinePlus website. Information provided includes symptoms, diagnosis, treatment, and the recent studies of these disorders. http://medlineplus.gov (http://medlineplus.gov)

Key Terms

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Click on each key term to see the definition.

amygdala (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#)

An almond-shaped structure located in the medial temporal lobe that is implicated in the experience of negative emotions.

arachnoid layer (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#)

The middle layer of the meninges.

basal ganglia (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#)

A group of subcortical nuclei that sends and receives information about movement to and from the cerebrum.

brain stem (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#)

Consisting of the midbrain, hindbrain, and diencephalon, the brain stem regulates our most primitive behaviors, such as breathing, sleep, sexual behavior, drinking, and eating.

cerebellum (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#)

The hindbrain structure that controls motor coordination and coordinates movement in response to sensory stimuli.

cerebral 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/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/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 outermost layers of the cerebrum that contain neurons.

cerebral hemispheres (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#)

The two (left and right) halves of the cerebrum.

cerebrospinal fluid (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#)

A watery fluid found in the ventricles of the brain and in the spinal cord.

cerebrum (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#)

The largest structure in the brain, believed to be the seat of consciousness.

cervical (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#)

The region of the spinal cord located in the neck.

coccygeal (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#)

The region of the spinal cord located at the base of the spine.

corpus callosum (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#)

The large tract that connects neurons in the left and right cerebral hemispheres.

cranial nerves (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#)

Twelve pairs of nerves that enter and exit the brain through holes in the skull.

diencephalon

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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/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/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 forebrain area that contains the thalamus and hypothalamus.

dura mater (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#)

The tough outer layer of the meninges.

forebrain (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#)

The largest part of the brain; it contains the cerebrum, basal ganglia, limbic system, thalamus, and hypothalamus.

frontal lobe (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#)

The most anterior lobe of the cerebrum; it contains the motor cortex and other centers of executive function.

ganglion (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#)

A cluster of neuronal soma in the peripheral nervous system.

hindbrain (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#)

The part of the brain immediately superior to the spinal cord; it consists of the medulla, pons, and cerebellum.

hippocampus (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#)

The limbic system structure that plays a role in emotions and memory.

hypothalamus (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#)

A structure in the diencephalon that controls the pituitary gland and regulates motivated behaviors.

inferior colliculi (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#)

Midbrain structures that receive and process auditory information.

limbic 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#)

The brain structures that regulate emotions.

lumbar (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#)

The region of the spinal cord located in the lower back.

medulla (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#)

The hindbrain structure that controls life-support functions.

meninges (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#)

The protective covering of the central nervous system.

meningitis (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#)

An infection of the meninges produced by bacteria.

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midbrain (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#)

The middle section of the brain; it consists of the tectum, the tegmentum, and a ventral region that contains the reticular formation.

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/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/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 area in the frontal lobe that directs fine motor coordination.

nerve (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#)

A bundle of axons in the peripheral nervous system.

occipital lobe (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#)

The most posterior lobe of the cerebrum; it processes visual information.

parietal lobe (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#)

The region of the cerebrum located immediately posterior to the frontal lobe; it processes somatic information relayed from the body.

pia mater (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#)

The innermost layer of the meninges.

pituitary 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#)

The master gland located below the ventral surface of the brain; it is connected to the hypothalamus by a stalk and receives commands from the hypothalamus to regulate the activity of other major glands in the body.

pons (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#)

The hindbrain structure that relays information from the medulla to the higher brain structures.

prefrontal 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/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/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 most anterior region of the frontal lobe that controls executive decision-making functions.

premotor 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/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/books/AUPSY350.13.2/sections/cover/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 area of the frontal lobe involved in planning, organizing, and integrating movements of the head, trunk, and limbs.

reticular formation (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#)

A group of neurons located in the brain stem that alerts the forebrain to important stimuli.

sacral (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#)

The region of the spinal cord located in the pelvic girdle.

septum (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#)

The structure in the limbic system associated with positive emotions and pleasurable feelings.

spina bifida (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#)

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A disorder in which the spinal cord is left exposed due to failure of the backbone to close during embryonic development.

spinal nerves (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#)

Nerves that enter and exit the spinal cord between bones of the spinal column.

superior colliculi (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#)

Midbrain structures that receive visual information and process the location of objects in the environment.

temporal lobe (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#)

The most inferior lobe of the cerebrum; it processes auditory, smell, and taste information and contains the hippocampus and amygdala.

thalamus (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#)

A structure in the diencephalon that relays information from the brain stem to the cerebrum.

thoracic (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#)

The region of the spinal cord located in the chest.

ventricles (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#)

Cavities in the brain that contain cerebrospinal fluid.