Download Biological Bases of Behavior

Biological Bases
of Behavior
AP PSYCHOLOGY UNIT III
Historical Perspectives

The idea of the “mind” has been
around since Plato

Franz Gall, a German physician,
believed that bumps on a persons
head could be used to determine
their personality and mental abilities


Right idea, wrong format

We know now that the brain has
specialized areas
Biological psychology: the scientific
study of the links between biological
and psychological processes
Micro to Macro

Biological psychology is best understood from the smallest parts to the
biggest parts

We know that all parts of us are made of cells

Nerve cells allow communication within the body

Individual cells make organs, organs make systems, systems work together
for us to live

There are specific systems in the brain with specific functions

A quick aside: There is A LOT of vocabulary in this unit. Expect a vocabulary quiz
daily.
Neurons & Neural Communication

The building block of the nervous system is the neuron, or nerve cell
Other “Parts” of the Neuron

Nodes of Ranvier: the spaces between the myelin sheath; essential for
allowing the message to travel quickly down the axon

Terminal Buttons: ends of the terminal branch of the axon; release the
chemicals into the synapse

Synapse: presynaptic neuron buttons, synapse, and postsynaptic neuron
dendrites

Synaptic cleft: space between neurons where chemicals are released and
absorbed by the next neuron to continue the action potential
Action Potential

The action potential is the process by
which a message is transported down a
neuron

When the neuron is not firing, it is at resting
potential


The neuron is relatively negative on the
inside and positive on the outside

There is more K+ on the inside, more Na+ on
the outside
The ion channels are selectively
permeable

K+ will flow slowly in and out, but Na+ only
enters when the sodium channels are open


In order for a neuron to fire, it needs to reach a minimum threshold

Each neuron has 2 types of messages being sent to it at the same time:
inhibitory & excitatory

If there are more excitatory, it will send the message

Na+ channels open and it enters the neuron, making the inside more
positive

K+ channels open and it leaves the neuron to return the inside to a
negative charge
All-or-none response – a neuron either sends the message or it doesn’t


Applies to a single message…we interpret a difference between a light
tap and a slap because there are more messages being sent at the same
time
Refractory period – the period of time after a neuron sends a message
when it cannot send another message
The action potential is a lot like flushing a toilet, if you think
about it. Explain how…
Neurotransmitters (NTs)

NTs are chemical
messengers released from
the axon of one neuron to
cross the synaptic cleft
and bind to receptor sites
on the dendrites of the
next neuron

Reuptake: when the
sending neuron reabsorbs
any NTs left in the cleft
How NTs Work & NTs to Know




NTs effect specific behaviors and emotions,
sometimes individually, other times in concert
with another NT
Particular brain pathways may use only 1or 2
NTs
Two types of NTs & Drugs

Agonist: stimulate a response

Antagonist: inhibit or block a response
Drugs work by either acting as an agonist or
antagonist

Opiates increase feelings of arousal

Botulin blocks ACh release and paralyze muscles

Top NTs to Know (Table 9.1)

Acetylcholine (Ach)

Dopamine

Serotonin

Norepinepherine

GABA

Glutamate

Endorphins
Nervous System

The Nervous System is the body’s communication
network made up of all of the nerve cells in the central &
peripheral nervous systems

Nerve: bundle of axons

2 main divisions of the nervous system


Central Nervous System (CNS): brain & spinal cord

Peripheral Nervous System (PNS): sensory and motor
neurons that connect the CNS to the rest of the body
Interneuron: neurons within the brain & spinal cord that
communicate internally and between the sensory inputs
and motor outputs
NERVOUS SYSTEM
CENTRAL
NERVOUS SYSTEM
PERIPHERAL
NERVOUS SYSTEM
Central Nervous System
BRAIN
SPINAL CORD

Where our thoughts, behaviors, &
emotions originate from

Connects the brain to the PNS and
vice versa

Made up of 40-86 Billion neurons,
400 Trillion synapses

Reflexes—automatic responses to
stimuli

Neuron clusters organize into
neural networks—connecting
with nearby neurons to create
quick, short connections

Experiences strengthen these
connections…that’s why
practice is important

Go through the spinal cord…a single
sensory neuron sends info to the spinal
cord, which activates a motor neuron
to send the response

Allows your body to react before your
brain has time to process what is
going on
Neural Chain, aka Reflex Arc
The brain processes
the sensory info
and decides what
to do
Sensory information
enters the body
through receptor
cells
Motor neurons
receive commands
from the brain and
react
NERVOUS SYSTEM
CENTRAL
NERVOUS SYSTEM
BRAIN
SPINAL
CORD
PERIPHERAL
NERVOUS SYSTEM
Peripheral Nervous System
SOMATIC NS
AUTONOMIC NS

Voluntary control of skeletal
muscle movements

Controls glands and muscles of the
internal organs

Almost everything you do is
controlled by this branch

Controls breathing, heart rate,
digestion

Some activities can be consciously
overridden (slowing your breathing
rate)

Broken into 2 subsystems

Talking

Walking

Writing

Sympathetic

Parasympathetic
NERVOUS SYSTEM
CENTRAL
NERVOUS SYSTEM
BRAIN
SPINAL
CORD
PERIPHERAL
NERVOUS SYSTEM
SOMATIC
NERVOUS SYSTEM
AUTONOMIC
NERVOUS SYSTEM
Autonomic Nervous System

Sympathetic Nervous System: alerts body to an emergency

Parasympathetic Nervous System: calms body after an emergency

Organs work under both sympathetic & parasympathetic


Eyes: pupils dilate (sympathetic) & contract (parasympathetic)

Stomach: inhibits digestion (sympathetic) & stimulates digestion
(parasympathetic)

Bladder: relaxes (sympathetic) & contracts (parasympathetic)
Sound File
NERVOUS SYSTEM
CENTRAL
NERVOUS SYSTEM
BRAIN
SPINAL
CORD
PERIPHERAL
NERVOUS SYSTEM
SOMATIC
NERVOUS SYSTEM
AUTONOMIC
NERVOUS SYSTEM
SYMPATHETIC
NERVOUS SYSTEM
PARASYMPATHETIC
NERVOUS SYSTEM
Endocrine System

Body’s slow communication system; glands that secrete hormones
into the bloodstream

Hormones: chemical messengers created by endocrine glands

Endocrine glands

Pituitary – “master gland” that influences release of hormones by other
glands; releases growth hormone & oxytocin (giving birth &
breastfeeding) – controlled by hypothalamus

Adrenal – pair of glands that secrete epinephrine (adrenaline) &
norepinephrine, which help arouse the body in times of stress
 Works
with sympathetic NS to initiate fight-or-flight

Thyroid – metabolism

Pancreas – regulates blood sugar
Brain Scanning Techniques

We can’t look into your brain and see your thoughts or emotions, but
we can see what your brain is doing when you have thoughts and
experience emotions

Lesions: destroyed brain tissue; naturally or experimentally caused

Electroencephalogram (EEG): amplified recording of energy waves
across the brain’s surface

Computed Tomography (CT) Scan: x-rays taken from a variety of
angles and combined into a composite representation of a slice the
brain

Positron Emission Tomography (PET) Scan: shows brain area’s
consumption of glucose, which occurs when an area is active;
person is given a task and we can see what part of the brain is used
to complete it


Magnetic Resonance Imaging (MRI): using magnetic fields and radio
waves to produce images of the brain; shows us the parts

Head is put into a strong magnetic field, then radio waves disorient the
atoms in the brain

When the atoms return to their normal spin they emit signals that provide
detailed pictures
Funtional MRI (fMRI): shows structure and function of brain by showing
bloodflow


Look at MRIs taken seconds apart to see changes when completing a
task or looking at a picture
Brain Scans
Older Brain Structures

Structures of the brain that control base needs: breathing, sleeping,
feeding

Brainstem: oldest part of the brain, starts at the top of the spinal cord,
made up of the medulla & pons.

Medulla: base of the brainstem; controls heartbeat & breathing

Pons: controls movement

People in a vegetative state have damage above the brainstem-they
can still breathe, their heart pumps, but other faculties have been lost

Mike the Headless Chicken

Also the nerve crossover point that allows the right hemisphere to control
the left side of the body and vice versa

Thalamus: pair of egg-shaped structures that sit on top of the
brainstem; act as your sensory relay station taking information from
every sense except smell and routing it to the appropriate part of the
brain.

Reticular Formation: netlike nerve network that goes from the spinal
cord through the thalamus. Filters some of the sensory information
going to the thalamus and sends it on to other brain areas.


Also plays a role in arousal.
Cerebellum: at rear of the brainstem, split in two, it looks like a minibrain. Has many roles—enables nonverbal learning, memory, helps
judge time, & moderate emotions.

Coordinates voluntary movement…if you are an athlete, dancer, can
drive a car…thank your cerebellum.
Limbic System

Located between the hemispheres and brainstem.

Primarily associated with emotions & drives.

Amygdala: two nerve clusters the size of lima beans. Strong link with
aggression & fear.


Hypothalamus: below thalamus; regulates many bodily functions
including hunger, thirst, body temp, sexual behavior.


Kluver & Pucy study of rhesus monkey by removing/stimulating
amygdala.
(Olds, 1975) through accidental placement of an electrode,
psychologists discovered that hypothalamus contains a reward center.
Rats would continuously press a button that stimulated that part of the
brain. They would even run over electrified floors to get to the button.
Hippocampus: connected with memory.
Cerebral Cortex-Structure

The cerebral cortex is the outer layer of the 2 hemispheres of the
brain. It is where high-level thinking occurs.

Glial cells: cells that support neurons by providing nutrients & myelin,
guiding neural connections, and cleaning up ions & NTs.

Broken into 2 hemispheres with 4 lobes each

Frontal: speaking, muscle movement, judgment, emotions, planning

Parietal: behind frontal; receives sensory input for touch & body position

Occipital: at back of head; receives info from visual fields

Temporal: above ears; primarily the auditory area
Cerebral Cortex-Function


Motor cortex: strip at back of frontal lobes

Controls motor function

Mapped out by body part (p. 106); the more precise the control, the
larger the area devoted

Psychologists & physicians are able to map this out because your brain
has no sensory nerves, allowing the patient to remain awake during
brain surgery
Somatosensory cortex: strip at front of parietal lobes

Processes body touch and movement sensations

Similar to the motor cortex, each body part has its own spot

The more sensitive the body part, the larger the space

There are other areas of the brain that deal with sensory information
beside touch
Association Areas

Areas of the cerebral cortex not involved in primary motor or sensory
functions

Can’t map them like the sensory & motor areas

Prefrontal cortex: judgment, planning, processing new memories

Parietal lobes: areas believed to be connected to math & spatial
reasoning

Right temporal lobe: facial recognition (if damaged, you would still
recognize facial features, but not who the person is)

Broca’s area: speaking

Wernicke’s area: understanding language Aphasia Patient
Aphasia Patient
Plasticity & Other Stuff

Plasticity is the brain’s ability to change and reorganize after damage
and form new pathways as the result of experiences

Some brain functions seem set in location, while others are able to be
reorganized

Neurons are a different matter-if they are severed, they do not
regenerate…if your spine is cut, you will be paralyzed

Neurogenesis: formation of new neurons


Occurs deep in the brain, then neurons migrate
Brain-Computer Interfaces

Psychologists have been able to implant electrodes in certain parts of
the brain and connect that to a computer that is able to complete a
task the person is thinking about…Just think of the applications!
Brain Hemispheres

The corpus callosum is a bundle of nerves that connects the 2
hemispheres of the brain and facilitates communication.

Split brain refers to patients whose corpus callosum has been
severed, or in some cases never developed. This procedure is usually
performed to stop excessive neural activity and seizures.

Psychologists learn a great deal from these patients about the functions
of each hemisphere and other specialized areas of the brain.

They also help better understand the interesting organization of sensory
information coming in through the eye.

Man with Split Brain
You have probably heard people talk about being “rightbrained” or “left-brained”, but those are inaccurate
statements. We all use all of our brain, it’s just that some of us
are more specialized in one hemisphere’s skills.

Left Hemisphere

Right Hemisphere

Logical

Visual

Language centers

Artistic

Speech

Excels at making
inferences
Consciousness

Consciousness is our awareness of ourselves and environment. It is
what allows us to “read” our surroundings and survive. It also provides
us with long-term vision, so to speak. Without consciousness, we
would live only for right now, seeking pleasure, without considering
the consequences of our actions.

Cognitive neuroscience seeks to study how brain activity is linked to
cognition (perception, thinking, memory, language).

With scans, psychologists can see that some non-communicative
patients brains are stimulated in areas associated with activities they
are imagining.
Dual Processing

Psychologists are discovering that our brain works on two separate
tracks, conscious and unconscious, simultaneously.


When we see an object in front of us, we consciously identify it (that’s a
baseball). At the same time, our brain is processing information about
the ball.
A lot of what we do occurs below our conscious thought. These
unconscious actions and processes allow us to focus our conscious
thoughts on more immediate concerns.
Behavior Genetics

The study of the power and limits of genetics on behavior.


In other words, how much effect does your nature have on
behavior…Nature vs. Nurture.
The human body has 20,000-25,000 genes.

Some are active, others are inactive-waiting to be turned on by your
environment.

As a human race, we are a lot more alike than we are different
because of our genetic makeup.

Psychologists are looking at the differences between individuals.

There isn’t one gene for aggression, many genes come together to
influence that trait.
Twin & Adoption Studies

The single best way to determine the effect of nature and nurture on
behavior because you are separating the two.

Identical twins are especially important to study because of their
genetically identical makeup.


Key point: they have the same genes, but not always the same number
of genes-that is why one twin might develop a disease the other may not.
Fraternal twins also serve as good subjects because while they are no
more similar than regular siblings, they are raised at the exact same
time period eliminating variables related to the time period a child is
raised in.

Identical twins separated at birth have been studied since about
1980.

There are some examples of separated twins that have led remarkably
similar lives, see the “Jim’s” story in your book.

What twin studies tell us is that nature and nurture play a pretty even role
in our behavior.

It’s important to note that a genetic predisposition does not mean a
person will develop a disease, certain personality trait, or grow to be
exactly 5’10’’. It means that genetic markers indicate it could happen.


The other side of separated twin studies is the environment they are
raised in. These studies give us a pure look at environmental
influences since the children bear zero genetic relationship to their
adoptive parents.

People who grow up together do not have similar personalities, whether
they are genetically related or not. Think about you and your
siblings…how much do you have in common with each other?

This does not mean that environment does not influence our personality.
Adoption does seem to have a positive effect on adopted children.

Adopted children tend to score higher on intelligence tests & be more
well-adjusted than their bio parents.
Molecular Genetics

Study of the molecular structure and function of genes

Looking at individual genes to see if they can determine who would
be predisposed to a certain disease

They would look at a family with generational history of bipolar, for
example, and take blood samples to look at each person’s DNA

What are the ethical implications of knowing this when a woman is
pregnant? What types of actions might be taken by someone who’s
child has been labeled “at risk for disease x”?
Heritability

First off, this does not mean inherited!

Heritability is the extent to which variation among individuals can be
attributed to genetics.

Having two eyes has 0 heritability, essentially everyone has 2 eyes.

Height or intelligence are highly heritable - diabetes and cancer are
less heritable.

As environments become more similar, heritability increases.

If people had similar genetics but different upbringings, heritability
would decrease.
Gene-Environment Interaction

Our genetics and environments interact to create our personality.

Are boys rough and girls gentle because it’s their nature, or does the
environment encourage it?


Boy v. girl baby

Boy v. girl toys
Epigenetics is the study of environmental influences on gene
expression without DNA changes

Agouti Mice
Evolutionary Psychology

Remember that evolutionary psychology is the study of the evolution
of behavior and the mind.

Natural selection: inherited trait variations that contribute to
reproduction and survival will most likely be passed on.

Mutation: random error in gene replication that results in a change.

Differences between groups (5%), ie-India vs. Russia, is less than
differences within groups (95%)


Because of natural selection…those that asked the right questions and
stayed alive procreated and created offspring, those that ate the
poisonous plants and tried to pet the leopards usually died
Today: evolutionary psychology is used to answer many questions
Nature-Nurture

We are a true combination of both, but neither is totally
predetermined.

We can choose not to reproduce, we can choose not to go with the
crowd.

Does our environment shape us, or do we shape our environment?

Figure 15.1 Biopsychosocial approach