AP Psychology
Chapter Two
Neuroscience and Behavior
I.
Neural Communication: Biological Psychologists study the Iinks
between biological activity and psychological events.
A. Neurons: Are nerve cells that each consist of a cell body,
dendrites, and axons (away).
1. Dendrites receive info.
2. Axons pass info. Along to other neurons.
3. Fatty tissue known as myelin sheath insulates the
axons of some neurons speeding up
transmission.
4. As seen in multiple sclerosis patients, if the
myelin sheath begins to break down,
communication to muscles begins to slow
and will eventually lead to loss of muscle
control.
5. Speeds can range from 2-200 miles per
hour.
B. Neural Transmission: A neuron fires an impulse when it receives
signals from sense receptors stimulated by pressure, heat, or
light, or when it is stimulated by chemical messages from
adjacent neurons.
1. This impulse is known as an action potential
(electrical charge).
2. Neurons, like batteries, generate electricity from
chemical events.
3. Electrically charged atoms called ions are
exchanged in this chemistry to electricity
process.
4. Fluid inside resting axon is mostly negatively
charged while fluid outside axon membrane is
mostly positively charged.
5. This separation of neg./pos. (known as resting
potential) occurs b/c an unmyelinated axon's
membrane is selectively permeable.
6. In other words, the pos. ions can't get through.
7. However, when the neuron fires, the first bit of the
axon opens its gates allowing pos. ions to flood in
causing depolarization.
8. Depolarization causes the next axon channel to open
and so on ... (dominoes).
9. During a resting phase, the pos. ions are
pumped back outside.
1 O.Then the neuron can fire again.
11 .If myelinated, the action potential speeds up.
C. Excitatory and Inhibitory signals: Neurons make decisions based
on the signals they receive. Most neurons have a resting rate of
random firing that either increased or decreases w/input from other
neurons.
1. Excitatory signals accelerate neurons.
2. Inhibitory signals slow neurons down.
3.If excitatory signals - inhibitory signals exceed a minimum
intensity, called the threshold, the combined signals trigger an
impulse.
4. Increasing the stimulus above the threshold DOES NOT
increase the impulse's intensity or speed.
1. Ex. Like guns, neurons either fire or they don't
and squeezing the trigger harder won't make the
bullet go faster.
2. A strong stimulus CAN trigger more neurons to fire
and to fire more often.
D. How Neurons Communicate: Neurons are separated by a very
small junction known as a synapse. We refer to this as a synaptic gap
or cleft.
1. When the action potential reaches the knoblike terminals
at an axon's end, it triggers the release of chemical
messengers known as neurotransmitters.
2. These fill the gap and allow for the "kiss" to take
place OR ions to enter the receiving neuron either
exciting or inhibiting its readiness to fire.
3. Excess neurotransmitters are reabsorbed by the
sending neuron in a process known as reuptake.
4. Many drugs increase the availability of selected
neurotransmitters by blocking their reuptake.
1. Ex.
E. How Neurotransmitters influence us: motions and emotions.
1. Dopamine: Influences movement, learning, attention, and
emotion. Excess dopamine has been linked
w /schizophrenia.
2. Serotonin: Affects mood, hunger, sleep, and arousal.
Prozac and other antidepressants raise serotonin levels.
3. Nor epinephrine: helps control alertness and arousal.
4.GABA (gamma-amino butyric acid) serves inhibitory
functions and is sometimes implicated in eating disorders and
sleep disorders.
5. Acetylcholine: Works on 'neurons involved in muscle, action,
learning, and memory. Alzheimer's patients experience a
deterioration of those neurons that produce this critical chemical
messenger.
F. Acetylcholine: More info.
1. ACh is the messenger at every junction between a motor
neuron and skeletal muscle.
2. When released to our muscle cells, the muscle contracts.
3. If transmission is blocked, our muscles cannot contract.
4. Ex. Curare-hunting darts-paralysis.
5. Ex. Botulin-paralysis.
3. Ex. Black widow's poison-not blocked but allowed to flood
causing violent muscle contractions, convulsions, and possible
death.
G. The Endorphins: Neurotransmitters similar to morphine that re
produced in the brain and elevates mood and eases pain.
1. These natural opiates are released in response to pain
and vigorous exercise. Ex. "runner's high".
H. How Drugs and Other Chemicals Alter Neurotransmission:
1. When flooded w / opiate drugs such as heroin and
morphine the brain may stop producing its own natural
opiates. When this drug is withdrawn, the brain is
deprived of any form of opiate, which is not pleasant for
the drug addict.
2. Drugs affect communication at the synapse often by
exciting or inhibiting neuron firing.
1. Agonists excite by mimicking a particular
neurotransmitter or by blocking its reuptake.
2. Antagonists inhibit by blocking neurotransmitters or
by diminishing their release.
3. New therapeutic drugs are being created to address
neurotransmitter related problems.
4. The brain-blood barrier makes creating drugs
harder than you'd think b/c the brain can block out
chemicals in the blood.
1. Ex. Parkinson's patients can not take a drug
that mimics dopamine b/c it is blocked by the brain and
can't slither through the barrier.
2. However, if given the raw material L-dopa,
which can sneak through, the brain can convert this to
dopamine and as a result decrease the deficit.
II.
III.
IV.
v.
The Nervous System: Our body's primary info. system.
A. The (CNS) is made up of the brain and spinal cord while the (PNS) links the CNS
w/ the body's sense receptors, muscles, and glands.
B. Info. travels in the nervous system via 3 types of neurons:
1. Sensory neurons carry INCOMING info. from the sense receptors to the CNS.
2. Interneurons are CNS neurons that internally communicate and intervene
between the sensory inputs and motor outputs.
3. Motor neurons carry OUTGOING info. from the CNS to the muscles and
glands.
C. Our nerves serve as electrical cables by bundling the sensory and motor axons
carrying PNS info.
1. Ex. Optic nerve: billions of axons in a single cable carrying info. from eye
to brain.
The Peripheral Nervous System: Consist of two components: Skeletal/somatic and
Autonomic
A. The somatic controls voluntary movements of skeletal muscles.
B. . The Autonomic controls the gland and muscles of our internal organs
1. Usually operates on its own to influence internal functioning.
2. But, can be consciously overridden sometimes.
3. This is a dual sys. that usually work together to maintain a steady internal state.
4. If needed, the sympathetic ns sys. arouses us for defensive action.
5. When the stress subsides, the parasympathetic ns produces opposite
effects to calm us down.
The Central Nervous System: Our spinal cord and brain allow neurons to talk to other
neurons which enable our humanity-our thinking, feeling, and acting.
A. Spinal cord: an information highway connecting the PNS to the brain.
1. Ascending neural tracts send up sensory info. and descending tracts send back
motor-control info.
2. Our reflexes are automatic and our body reacts before our brain receives info.
to feel pain b/c of interneurons.
3. However, to produce bodily pain or pleasure, the info. must reach the
brain.
B. The Brain: receives info., interprets it, and decides responses.
1. Our neural networks strengthen connections between neurons b/c certain
patterns of input will produce a given output.
The Brain
A. Tools of discovery: we've come a long way baby!
1. Lesion production allows us to observe the effects of brain diseases and
injuries. (can be produced surgically in animals)
2. Why wait for an injury when you can, electrically, chemically, and
magnetically stimulate parts of the brain and note the effects.
3. EEG is an amplified recording of the electrical activity that sweeps across the
brain's surface.
4. Neuroimaging techniques allow us to see inside the brain w/o lesioning it.
1. CT scan: x-ray photos that can reveal brain damage.
2. PET scan: sugar glucose is injected into patient and where this sugar
concentrates tells us which parts of the brain are active during a given
task.
3. MRI: head is put into strong magnetic field, which aligns spinning atoms.
Brief radio waves disorient atoms and when they return to their normal
spin signals are detected. These signal concentrations can be seen. Ex.
schizophrenia.
4. Functional MRI: brain lights up when participant is asked to perform
different mental functions.
VI. Low-level Brain Structures: functions w/o any conscious effort and sustains basic life
functions as well as enables memory, emotions, and basic drives.
A. The Brainstem (basement/custodians): begins where the spinal cord enters the
skull and swells slightly forming the medulla.
B. The medulla is responsible for heartbeat and breathing/automatic survival
functions.
C. The reticular formation runs the brain stem passing through the medulla and up
to the thalamus. It controls arousal.
D. The thalamus is the brain's switchboard for all sensory info. except smell. It
receives info. from the senses and routes it to various higher brain regions.
E. The cerebellum (little brain) most obvious function is coordinating voluntary
movement.
F. The limbic system is located at the border of the lower brain's part and the
cerebral hemispheres and plays a part in emotions and basic drives.
1. The hippocampus is the only part of this system that processes memory;
2. The amygdala influence aggression and fear. Must remember however,
that this is not the only part of the brain involved in such emotions.
3. The hypothalamus helps keep the body's internal environment in a steady
state by regulating thirst, hunger, and body temperature. Sexual behavior is
also influenced much like a reward system (built in). Reward deficiency
syndrome has been proposed for addictive behaviors such as alcoholism,
drug abuse, and food binging.
VII. The Cerebral Cortex: like bark on a tree it is the thin outer covering of
our brain and is our body's ultimate control and info. processing
center.
A. Structure of the cortex: thin surface of the cerebral hemispheres
(left/right).
B. Each hemisphere is divided into 4 lobes. Each lobe carries out
many functions and some of these functions require the interplay of
several lobes.
1. Frontal lobes: just behind forehead. Speaking, muscle
movements, and speaking. Motor strip lies at the rear.
2. Parietal lobes: top of head and toward rear. Includes the
sensory cortex.
3. Occipital lobes: back of head. Visual cortex receives info.
from opposite visual field.
4. Temporal lobes: above ears. Auditory cortex receives auditory
info. primarily from the opposite ear.
C. Functions of the cortex: Motor functions, sensory functions, and
association functions. *Beware! Complex activities involve many
brain areas.
1. The motor cortex sends messages out to the body and can be
stimulated to make different body parts move(simple) .
. ,. ~
Opposite body parts move from the side stimulated.
2. Those areas that require precise control, occupied the greatest
amount of cortical space. Ex. fingers and mouth.
3. *Functional MRIs show, however, that most movements
require more than one part of the brain:
D. The sensory cortex: receives incoming messages.
1. The more sensitive a body region the greater the area of the
sensory cortex devoted to it. Ex. lips, foes
2. If you lose a finger that region of the sensory cortex receives
info. from your other fingers making them more sensitive.
3. Nurture is also involved. "WELL PRACTICED" pianist have
larger than usual auditory cortex area that encodes piano sounds.
4. The visual cortex part of your occipital lobes processes visual
info.
..
E. The other 3/4s of our brain not committed to sensory or muscular
activity is referred to as our association areas.
1. No part of our brain is not used.
.
·
..•.
;'
VIll
. . .. 'I
IX.
2. For ex. the associations areas in our frontal lobes allow us to
plan, judge, and process new memories.
3. Electronically probing these areas produces no observable
responses.
4. Frontal lobe damage can also affect personality. Ex. Phineas
Gage.
5. Assoc. areas of the parietal lobe are involved in math and
spatial reasoning.
6. An area on the underside of the right temporal lobe enables us to
recog. faces. If damaged, couldn't recog. your own mom.
F. Language requires the use of many brain areas.
1. For ex. damage to any of several cortical areas can cause an
••
impaired use of language known as aphasia.
2. Left 'frontal lobe: Broca's area (Tom Brokaw): disrupts
speaking.
3. Left temporal lobe: Wernicke's area: disrupts understanding.
4. Angular gyrus: could speak and understand but not read.
G. In summary, the brain's specific subsystems are localized in
particular regions, yet the brain acts as a unified whole.
Brain Reorganization: .Nurture reveals the plasticity of the brain.
A. Even though severed neurons are not likely to regenerate, neural
tissue can reorganize in response to damage.
1. Ex. Monkeys arm severed-sensory area shifted to face.
2. Ex. cat's eye-laser damages spot in eye-other areas of the eye
gain sensory area.
3. Ex. Blind people have greater area of sensory cortex devoted to
touch.
B. New evidence reveals that adult humans can generate new brain
cells.
., ~
1. Brains way to compensate for gradual loss of neurons.
2. Master "stem cells" that can dev. into any type of brain cell
could be used in a diseased brain. (?)
3. The younger our brains the more plastic.
4. Ex. Hemispherectomies.
Our Divided Brains: Two hemispheres serve different functions.
A. Left hemisphere: reading, writing, speaking, arithmetic reasoning,
and understanding.
B. Right hemisphere: understands simple requests and easily
perceives objects.
C. Split brain patients (cut the corpus callosum) show hemispheric
differences.
D.
Our Intact brain hemispheric differences:
E. Right hemisphere: perceptual tasks.
1. Ex. recog. picture faster and more accurately
B. Left hemisphere: speaks or calculates.
1. Ex. recog. work faster and more accurately
2. Ex. Zulu lang. heard clicks in right ear and more accurately
recog.
3. Ex. Sign lang. is processed in left hem.
XI. Handedness: Is it inherited?
A. Genes or some prenatal factor influences handedness.
1. Ex. newborn study
2. Poor Kelsea!
XII. The Endocrine System: Hormones released by endocrine glands
forms the body's slower information system. (pg.81 diagram)
A. Glands secrete other forms of chemical messengers known as
hormones.
1. These chemicals travel via the bloodstream.
2. They influence our interest in sex, food, and aggression.
3. This system takes longer but the effects usually last longer than
the effects of a neural message.
B. Your adrenal glands release epinephrine and norepinephrine
which increase heart rate, blood pressure, and blood sugar,
providing us with a surge of energy.
1. When the emergency passes, the hormones and their effects
linger for a while.
C. The pituitary gland (master gland) is controlled by the
hypothalamus AND is also a controller in its own right.
1. Releases the growth hormone.
2. Signals sex hormones to release sex hormones.
D. The nervous and endocrine systems are so interconnected the
distinction between them sometimes blurs.