psychology assignment
reno-s
SAIntroCh2.pptxBIOLOGY AND BEHAVIOR
Chapter 2
PSYCHOLOGY DEBORAH M. LICHT MISTY G. HULL COCO BALLANTYNE
1
Biology and Behavior
Brandon Burns poses for a photo at the Marine Corps Recruit Depot in Parris Island, South Carolina, in the fall of 2003. The following year, he was shot in the head by an enemy sniper in the Battle of Fallujah.
Doctors concluded that some parts of his brain were no longer viable. “They removed part of my skull and dug out the injured part of my brain,” and now, Brandon says, “one third of my brain is gone.”
What were the consequences of his injury?
2
A Complex Communication Network
Nervous system
A communication network that conveys messages throughout the body, using electrical and chemical processes
Brain
An intricate, dynamic connections web that provides the power to think and feel in ways that differ from and are more complex than in other organisms
Contains between 86 and 100 billion nerve cells that can each typically communicate with other cells through a system of an estimated 100 trillion links
3
The Last Frontier: From Bumps to Brain Scans (part 1)
Neuroscience
Involves the study of the brain and nervous system
Draws upon multiple disciplines, including psychology
Biological psychology
A subfield of psychology
Focuses on how the brain and other biological systems influence human behavior
4
The Last Frontier: From Bumps to Brain Scans (part 2)
EARLY
Franz Joseph Gall (1757−1828)
Early ”brain” scientist and neuroanatomist
Phrenology
Pierre Flourens (1794−1828)
Ablation and physiology
Explained that areas of the brain might have particular functions
CONTEMPORARY
Horikawa and colleagues; Hsu and colleagues
Observing the brain as it sleeps, reads, tells lies
Max-Planck-Gesellschaft
Manipulating activity of individual brain cells
Optogenetics
5
Ways to Study the Living Brain
Looking at brain STRUCTURE
Computerized axial tomography (CAT)
Magnetic resonance imaging (MRI)
Watching brain FUNCTION
Electroencephalogram (EEG)
Positron emission tomography (PET)
Functional magnetic resonance imaging (fMRI)
What’s next? MAKING CONNECTIONS
Diffusion spectrum imaging (DSI)
See INFOGRAPHIC 2.1 for additional information.
6
Can you identify the structure of a typical neuron?
Cell body
Dendrites
Axon
Terminal buds
Nodes of Ranvier
Myelin sheath
Synapse
7
The Neuron
The neuron, the basic building block of the nervous system, has three main components: (1) a cell body, which contains vital cellular structures; (2) bushy dendrites that receive messages from neighboring neurons; and (3) a long, thin axon that sends messages to other neurons through its branchlike terminal buds. James Cavallini/Science Source.
8
Holding It Together: Glial Cells
Glia to the rescue
A scanning electron micrograph shows neurons (green) and glia (orange)
Glial cells serve as the “glue” of the nervous system, providing cohesion and support for the neurons. Some classes of glial cells
Microglia
Astrocytes
Schwann cells
9
Neurons and Neural Communication (part 1)
PROCESSES INSIDE THE NEURON
The neuron is surrounded by and filled with positive and negative electrically charged ions.
The difference in sum of the positive and negative charges determines charge overall.
Two processes direct ion flow into and out of the cell:
Diffusion
Electrostatic pressure
The summation of negatives and positives produces the voltage neuron difference.
Neurons and Neural Communication (part 2)
PROCESSES INSIDE THE NEURON
A selectively permeable neuron membrane allows selectively ion movement in and out of its channels.
Positive sodium ions
Negative protein ions
Ion passage through the membrane plays an important role in how neurons transmit information.
Here’s what is going on when the neuron is not active: The negative protein ions are only on the inside of the cell, but they are attracted to the excess positive charge outside and move toward the membrane. Because the protein ions (–) are too big to get through the membrane, the inside of the neuron is negatively charged (Infographic 2.2). Although there are some positive potassium ions inside the neuron, the concentration of sodium ions (+) outside the cell is much greater than that inside. As a result, sodium ions on the outside are attracted to the membrane (because of diffusion and electrostatic pressure).
11
Biology and Behavior: Processes Inside the Neuron (part 1)
COMMUNICATION WITHIN AND BETWEEN
Resting potential
Electrical potential of cell at rest
Solutions on either side of the membrane wall come into equilibrium, with a slightly more negative charge inside.
12
Biology and Behavior: Processes Inside the Neuron (part 2)
COMMUNICATION WITHIN AND BETWEEN
Action potential
Involves spike in electrical energy that passes through the axon of a neuron, the purpose of which is to convey information
Is all-or-none
Every time a segment of the axon fires
Positive sodium ions flood in from the outside of the cell, while the prior segment returns to its resting potential, all along the length of the axon to its end.
How does a neuron convey the strength of a stimulus?
By (1) firing more often, and (2) delivering its message to more neurons. Consider a loud scream and a quiet whisper. The loud scream is a stronger stimulus, so it causes more sensory neurons to fire than the quiet whisper. The loud scream also prompts each neuron to fire more often.
13
Biology and Behavior: Processes Inside the Neuron (part 3)
COMMUNICATION WITHIN AND BETWEEN
Excitatory signals
Occur when enough signals combine and sending neurons signal the receiving neuron to pass along the message
Inhibitory signals
Inhibit neuron from releasing a signal through the axon
All-or-none
Action potentials are all-or-none.
The neuron conveys stimulus strength by firing more often and delivering its message to more neurons.
14
Biology and Behavior: Processes Inside the Neuron (part 4)
The myelin sheath insulates and protects the tiny spikes in electricity happening inside the axon.
Action potential “skips” over the segments of myelin, hopping from one node to the next, instead of traversing the entire length of the axon.
Myelin
Protein that envelops and insulates the axon, facilitating faster transmission of the impulse
Action potentials may travel as fast as 268 miles per hour through a myelinated axon (Susuki, 2010). Myelin is a protein that envelops and insulates the axon, facilitating faster transmission. The action potential “skips” over the segments of myelin, hopping from one node of Ranvier to the next (see small space in the center), instead of traversing the entire length of the axon. Jean-Claude Revy, ISM/Phototake.
15
Biology and Behavior: Communication Between Neurons
Neurotransmitters
Chemical messengers that neurons use
Receptor sites
Location where neurotransmitters attach on the receiving side of the synaptic gap
Reuptake
Occurs when neurotransmitters are reabsorbed by the sending bud
Diffusion
Occurs when neurotransmitters are not reabsorbed and drift out of the synaptic gap
16
Biology and Behavior: The Synapse
The terminal bud of a sending neuron (top) interacts with a dendrite of a receiving neuron by releasing chemical messengers (neurotransmitters) into the synapse.
Once the neurotransmitters migrate across the gap and latch onto the dendrite’s receptor sites, the message has been conveyed.
See INFOGRAPHIC 2.3 for graphic presentation of communication between neurons.
17
Biology and Behavior: Neurotransmitters and Behavior
NEUROTRANSMITTERS
Approximately 100 neurotransmitters have been discovered.
Neurotransmitters secreted by one neuron under certain conditions can cause neighboring neurons to fire, which can affect the regulation of mood, appetite, muscles, organs, arousal, and a variety of other functions.
See Table 2.5 for additional information about the surprising effects of neurotransmitters.
18
Biology and Behavior: Neurotransmitters and Behavior (part 1)
ACETYCHOLINE
Relays messages from motor neurons to muscles, enabling movement; involved in memory
Low levels linked to Alzheimer’s disease
Too much = spasms; too little = paralysis
Potential wonder drug for disease treatment
GLUTAMATE
Makes neurons fire; central role in memory and learning
Too much = strokes; too little = symptoms of schizophrenia
GABA
Inhibits neurotransmitter firing; contributes to motor control and vision
Roles in sleep and wakefulness
Decreased with long-term alcohol use
19
Biology and Behavior: Neurotransmitters and Behavior (part 2)
NOREPINEPHRINE
Has variety of effects in CNS; helps body prepare for stress
Plays important role in maintaining attention
High levels lead to over-arousal and hypervigilance
SEROTONIN
Plays key role in controlling appetite, aggression, and mood; regulates sleep and breathing
SSRIs boost effects of positive feelings
DOPAMINE
Plays role in abuse of some substances (cocaine and amphetamines)
Impacts attention, learning through reinforcement, and regulation of body movement
20
Biology and Behavior: Neurotransmitters and Behavior (part 3)
ENDORPHINS
Regulates secretion of other neurotransmitter; naturally produced opioids; reduces pain and elevates mood
AGONISTS
Interfere at level of synapse; increase normal neurotransmitter activity
ANTAGONISTS
Interfere at level of synapse; decrease normal neurotransmitter activity
21
The Supporting Systems: Overview of the Nervous System
The brain needs supporting infrastructure to carry out directives and relay essential information from outside.
Central nervous system (CNS)
Peripheral nervous system (PNS)
The nervous system is made up of the central nervous system, which includes the brain and spinal cord, and the peripheral nervous system.
22
The Supporting Systems
SPINAL CORD
Includes bundle of neurons; Connects with the body’s muscles, glands, and organs
SPINAL CORD RESPONSIBILITIES
Receiving information from the body and sending it to the brain
Taking information from the brain and delivering it throughout the body
23
The Supporting Systems: Types of Neurons
SENSORY NEURONS
Receive information about the environment from the sensory systems and convey it to the brain for processing
MOTOR NEURONS
Carry information from CNS to produce movement; provide mechanism regulated by spinal cord and the brain
INTERNEURONS
Reside in the brain and spinal cord; act as bridges connecting sensory and motor neurons
24
THE SPINAL CORD AND REFLEX ARC
Without any input from the brain, the spinal cord neurons are capable of creating some simple reflexive behavior.
While the spinal reflex occurs, sensory neurons also send messages to the brain, letting it know what has happened.
This type of pain reflex includes a number of steps: (1) Your hand touches the hot pan, activating sensory receptors, which cause the sensory neurons to carry a signal from your hand to the spinal cord. (2) In the spinal cord, the signal from the sensory neurons is received by interneurons. (3) The interneurons quickly activate motor neurons and instruct them to respond. (4) The motor neurons then command your muscles to contract, causing your hand to withdraw quickly. A sensory neuron has a rendezvous with an interneuron in the spinal cord, which then commands a motor neuron to react—no brain required. We refer to this process, in which a stimulus causes an involuntary response, as a reflex arc.
25
What Lies Beyond: The Peripheral Nervous System (part 1)
PERIPHERAL NERVOUS SYSTEM (PNS)
Includes all neurons not in CNS
Involves neurons that are bundled together (nerves) to carry signals throughout body
Nerves
Act as primary communication system for PNS
Supply CNS with information about body’s environment
Have two functional branches: somatic and autonomic nervous systems
26
What Lies Beyond: The Peripheral Nervous System (part 2)
SOMATIC NERVOUS SYSTEM
Characteristics
Involves branch of the parasympathetic nervous system
Includes sensory nerves and motor nerves
Gathers information from sensory receptors
Controls the skeletal muscles responsible for voluntary movement
27
What Lies Beyond: The Peripheral Nervous System (part 3)
AUTONOMIC NERVOUS SYSTEM
Characteristics
Regulates involuntary activity
Has two divisions involved in physiological responses to stress or crisis situations
Sympathetic nervous system
Parasympathetic nervous system
28
The Sympathetic and Parasympathetic Nervous System
The autonomic nervous system has two divisions, the sympathetic and parasympathetic nervous systems. In a stressful situation, the sympathetic nervous system initiates the “fight-or-flight” response. The parasympathetic nervous system calms the body when the stressful situation has subsided.
Photo: PhotoObjects.net/Thinkstock/Getty Images.
29
What Lies Beyond: The Peripheral Nervous System (part 4)
HIS BRAIN, HER BRAIN
Hardwired differently versus socially conditioned to develop certain interests and skills
GENDER SIMILARITIES AND DISPARITIES IN BRAIN ANATOMY AND FUNCTION
Differences in asymmetry of cerebral hemisphere
Higher volumes of gray matter in female brain
Gender disparities in brain networks involving social cognition and visual-spatial abilities—some may be present early in development
Could some of these differences explain why genders are drawn to different areas of study?
Female response to stress
Many women have inclination to direct energy toward nurturing and forging social bonds as a stress response.
30
BACHELOR’S DEGREES AWARDED IN THE UNITED STATES
Bachelor’s Degrees Awarded in the United States
Women earn the majority (57.3%) of all bachelor’s degrees awarded in the United States. But when it comes to degrees awarded in science, math, and engineering, the numbers look very different. Why do so many fewer women receive degrees in STEM fields?
Information from the National Science Foundation, 2015.
31
The Endocrine System and Its Slowpoke Messengers
ENDOCRINE SYSTEM
Hormones
Pituitary gland
Thyroid gland
Adrenal glands
Can you define each of these? How do they influence behavior and physiological processes?
Together, these glands and organs can impact: (1) growth and sex characteristics, (2) regulation of some of the basic body processes, and (3) responses to emergencies. Just as our behaviors are influenced by neurotransmitters we can’t see and action by the endocrine system are also hard at work behind the scenes.
32
The Endocrine System
This system of glands communicates within the body by secreting hormones directly into the bloodstream. Photos: (left, face) Hemera/Thinkstock/Getty Images; (left, body) © Yuri Arcurs/Alamy; (right) Asiaselects/ Getty Images.
33
Two Hemispheres
RIGHT BRAIN, LEFT BRAIN: THE TWO HEMISPHERES
Cerebrum
Includes largest, most highly developed part of brain
Involved in intelligence, personality, thinking, perceiving, planning and organization, language, sensation, motor functions
Divided into right and left hemispheres and linked by corpus callosum
Corpus Callosum
Includes bundle of nerve fibers
Enables left and right side brain to communicate and to work together to process information
The cerebrum looks like a walnut with its two wrinkled halves.
It contains all brain parts expect the brainstem structures.
Regions of the left and right hemispheres specialize in different activities, but the two sides of he brain are constantly communicating and collaborating. Science Source.
34
The Hemispheres: Split-Brain Operation
Hemispherectomies
Exceptionally rare; last resort
Callostomies (split-brain operations)
Right and left hemisphere disconnected
MRI SCAN
Both hemispheres intact after hemispherectomy
35
The Split-Brain Experiment
36
The Hemispheres: Lateralization
Lateralization
Each cerebral hemisphere processes certain types of information and excels in certain activities.
Generalization
The left hemisphere plays a crucial role in language processing, and the right hemisphere plays a crucial role in managing visual spatial tasks.
But
Hemispheres constantly integrate and share information.
37
The Special Roles of the Left and the Right
Handedness and language dominance
The left hemisphere controls language in most people; it does not necessarily correspond to handedness.
Areas responsible for language production and comprehension
EARLY RESEARCH
Broca’s area originally thought responsible for speech creation
Wernicke’s area originally thought responsible for comprehension
TODAY
Areas perform additional functions and cooperate with multiple brain regions
The left hemisphere handles language processing in around 95% to 99% of people who are right-handed, but only in about 70% of those who are left-handed (Corballis, 2014).
38
Speak Again
Brandon works on his pronunciation in front of a mirror during a speech therapy session at the Memphis VA hospital. You can see the extent of his injury on the left side of his head. Upon awakening from his coma, Brandon could not articulate a single word. Today, he can hold his own in complex conversations.
39
The Hemispheres: Language Area and the Brain
Broca’s area
Wernicke’s area
Can you identify the role each structure plays in language production and comprehension?
40
The Hemispheres: The Role of the Right
RESEARCH: RIGHT HEMISPHERE
More proficient in some visual tasks
Critical for understanding abstract and humorous use of language
Better for following conversations that change topics
Important for recognizing faces
41
The Amazing Brain: Neuroplasticity
HUMAN STEM CELL
The brain undergoes constant alterations
Physical adaptation and repair—even after hemispherectomy
Growth of new connections and reorganization
Stem cells
Responsible for creating new neurons
Adult-born neurons exist
42
The Cortex: A Peek Beneath the Skull (part 1)
THE CORTEX
Cerebral cortex
Processes information and surrounds nearly all of the brain structure
Meninges
Contains three thin layers that envelop and protect brain and spinal cord
See INFOGRAPHIC 2.4 for additional information.
Peel away the scalp and cut away the bony skull, and you will find still more layers of protection. Three thin membranes—the meninges—provide a barrier to both physical injury and infection. Bypass them, and the outermost layer of the brain, the cortex, is revealed.
43
The Lobes: Specialized Areas of the Brain
Frontal lobe: higher-level cognitive functions like thinking, planning, and personality characteristics—located at the front and top of the brain.
Parietal lobe: integration of sensory information like touch and temperature—located at the top and back of the brain.
Occipital lobe: processing of visual formation—located at the back and center of the brain.
Temporal lobe: hearing and language comprehension—located at the center and front of the brain.
44
The Lobes: Up Close and Personal (part 1)
Phineas Gage and the frontal lobes
In 1848, Gage was impaled by a 3-foot tamping rod through his cheek, brain, and skull that caused dramatic changes in his personality.
Modern scientists revisited these data and suggested that damage occurred in both hemispheres.
Fritsch and Hitzig and the motor cortex
By applying a mild shock to dogs’ cortexes, researchers demonstrated that the motor cortex region is involved in muscle movement.
Albert Einstein and the parietal lobes
A postmortem comparison of 35 male brain specimens and Einstein’s brain found that the region of Einstein’s parietal lobe responsible for visual spatial cognition and mathematical was thinking 15% larger than those of the control group.
Do you think Einstein had a superbrain?
45
The Lobes: Up Close and Personal (part 2)
Penfield and the somatosensory cortex
Used method similar to Fritsch and Hitzig, showing which points along the motor cortex and somatosensory cortex corresponded to parts of the body
Developed model often represented by oversimplified “homunculus”
This illustration shows how areas on the motor and somatosensory cortex correspond to the various regions of the body. Parts of the body that are shown larger, such as the face and hands, indicate areas of greater motor control or sensitivity. The size of each body part reflects the amount of cortex allocated to it.
46
The Lobes: Up Close and Personal (part 3)
Occipital lobes
Initial processing site for visual information in lower back of head
Primary visual cortex
Connects to optic nerve, where visual information is received and interpreted
Association areas
Integrates information from all over the brain
Located in all four lobes
See Table 2.2 for summary of region of the cortex.
47
Social Media and Psychology
FACEBOOK IN THE BRAIN
Facebook friends range from zero to 5,000, averaging 338.
A preliminary study suggests friend volume may reflex something about a user’s brain.
There is a correlation between number of Facebook friends and density of gray matter in areas of the brain known for meaningful social movements (superior temporal sulcus) and facial recognition (entorhinal cortex).
So… are your Facebook friends a gray matter?
There is no shortage of data: “Each day, people send one billion posts to Facebook, tweet 400 million messages through Twitter, upload 12 years’ worth of videos to YouTube, and make 300,000 edits to Wikipedia” (Mesh, Tamir, & Heekeren, 2015, p. 771).
48
Digging Below the Cortex (part 1)
DRAMA CENTRAL: THE LIMBIC SYSTEM
Fuels basic drives and processes emotions and memories
Hippocampus
Amygdala
Thalamus
Hypothalamus
The limbic system includes the hippocampus, amygdala, thalamus, and hypothalamus.
Hypothalamus: A small structure located below the thalamus that maintains a constant internal environment within a healthy range; helps regulate sleep–wake cycles, sexual
behavior, and appetite.
Amygdala: A pair of almond-shaped structures in the limbic system that processes aggression and basic emotions such as fear, as well as associated memories.
Thalamus: A structure in the limbic system that processes and relays sensory information to the appropriate areas of the cortex.
Hippocampus: A pair of structures located in the limbic system; primarily responsible for creating new memories.
49
From the Pages of SCIENTIFIC AMERICAN
RESEARCH SUGGESTS SUGAR MAY HARM BRAIN HEALTH
Eating a lot of sugar or other carbohydrates can be hazardous to both brain structure and function.
Diabetes: Links to elevated risk of dementia and smaller hippocampus
High levels of glucose: Associated with worse memory, smaller hippocampus, and compromised hippocampal structure
CONCLUSION
Even in the absence of diabetes or glucose intolerance, high blood sugar may harm the brain and disrupt memory function.
Future research needed
And Now the Good News: Food for Thought?
DO YOU KNOW THE POTENTIAL BENEFITS FOR THE FOLLOWING FOODS?
Walnuts
Berries
Cocoa
Oily fish
Broccoli
See Table 2.3 for answer to the question.
51
Digging Below the Cortex (part 2)
COMPONENTS OF THE BRAINSTEM
Brainstem
Includes the brain’s core
Extends from spinal cord to forebrain
Forebrain
Involves largest part of the brain and includes cerebral cortex and limbic system
Midbrain
Involves brainstem part involved in arousal levels, responsible for generating movement patterns in response to sensory input
Located beneath the structures of the limbic system, the brainstem includes the midbrain, pons, and medulla. These structures are involved in arousal, movement, and life-sustaining processes. The cerebellum is important for muscle coordination and balance and, when paired with the pons and medulla, makes up the hindbrain. Photo: Onoky/Corbis.
52
Digging Below the Cortex (part 3)
COMPONENTS OF THE BRAINSTEM
Reticular formation
Involves network of neurons running through the midbrain
Controls levels of arousal and quickly analyzes sensory information on its way to the cortex
Hindbrain
Pons
Medulla
Cerebellum
Involves muscle coordination and balance
May also affect fine distinctions in cognition
53
And Now?
LIFE IS GOOD
Three years after his traumatic brain injury, Brandon celebrated his marriage to Laura. The couple now has three children.
54
