Transcript The Biological Basis for Behavior

The Biological Basis for
Behavior
The Human Brain
Bellringer 3
• List at least five things your brain does on a
daily basis.
I. Brain Basics
• A. Studying the brain
– 1. This area of the science of psychology is
experiencing an explosion of research
– 2. This is mostly due to changes in technology that
allow us to see the brain as it works.
• B. Phrenology
– 1. A concept developed by a German Physician
named Franz Gall.
– 2. The theory stated that bumps on the skull
revealed our mental abilities and personality
traits.
Phrenology
• C. Basic Terminology
– 1. Biological psychologist = a branch of
psychology concerned with the links between
biology and behavior.
– 2. Sometimes referred to as neuropsychology,
neuroscience, physiological psychology, or
biopsychology.
– 3. Neuroanatomy refers to the study of the
parts and functions of neurons
II. Neural anatomy and Neural
Communication
• A. Neurons the basic
building blocks of the
brain
– electrically transmit
data in your brain
– makeup 1/2 the volume
of the brain
Neurons
• B. Glial Cells support the neurons
– 1. may be 10 times as numerous as neurons
– 2. make up the other half of the volume of the
brain
• C. Neurons
– 1. Three types of
Neurons
• a. Sensory = neurons
that carry incoming
information from the
sense receptors to the
CNS also known as
AFFERENT
NEURONS.
Sensory Neuron
Sensory
Neuron
Brain
Spinal
Cord
Motor
Neuron
• b. Motor = the neurons
that carry outgoing
messages from the CNS to
the muscles and glands.
Also known as
EFFERENT NEURONS.
• c. Interneurons = CNS
neurons that internally
communicate and
intervene between the
sensory inputs and motor
outputs
Diagram of a Neuron
– 2. The structure of the Neuron
• a. Dendrites = the bushy, branching extensions of a
neuron that receive messages and conduct impulses
forward toward the cell body. Get its name from the
Greek word for tree.
• b. Axon = the extension of a neuron, ending in
branching terminal fibers, through which messages
are sent to other neurons or to muscles or glands
• c. The Soma = the Cell body – its function is to
support the cell. At the center is the nucleus
• d. The myelin sheath is a layer of fatty segmented
tissue that encases the fibers of many neurons
– Enables vastly greater transmission speed of neural
impulses as the impulse hops from one node to the next
– The Nodes of Ranvier = the nodes along the myelin sheath
• e. The Synapse = the junction between the axon tip
of the sending neuron and the dendrite or cell body
of the receiving neuron – also called the synaptic
gap or cleft
The Synapse
• f. The axon terminal = or
pre-synaptic terminal is
the bulb at the end of an
axon through which
neurotransmitters are
released. (AKA terminal
buttons, end buttons, and
synaptic knobs)
• g. Vesicles = bubble like
structures which contain
the neurotransmitters
• h. Neurotransmitters = chemical messengers that
transverse the synaptic gaps between neurons. They
create or inhibit the receiving neuron form
generating a neural impulse
• i. Synaptic receptor sites – AKA binding sites –
each site is like a lock keyed to the particular
chemical structure of each different type of
neurotransmitter
Neurotransmitters at work
– 3. The Neuron at Rest
• a. Resting potential = the interior cellular fluid of
the axon has a slightly higher negative charge. This
positive outside/negative inside polarization is
called resting potential
• b. The cell membrane is selectively permeable that
is it allows only certain ions in or out
• c. Sodium & Potassium pump = the resting cell
continually pumps three sodium ions out while
letting two potassium ions in – Since both of these
ions have a positive charge the result is a slight
decrease in the positive charge of the inside of the
cell
Ion concentrations
Outside of Cell
K+
Na+
Cl-
Cell Membrane in resting state
K+
Na+
Cl-
Inside of Cell
A-
The Cell Membrane is Semi-Permeable
K+
Na+
Cl-
Outside of Cell
Cell Membrane at rest
K+
Na+
ACl-
Inside of Cell
Potassium (K+)
can pass through
to equalize its
concentration
Sodium and
Chlorine cannot
pass through
Result - inside is
negative relative
to outside
- 70 mv
– 4. The Action Potential
• a. Action potential = a neural impulse
– i. A brief electrical charge that travels down an axon
– ii. The action potential is generated by the movement of
positively charged sodium ions into the axon
• b. Thresholds = the level of stimulation required to
trigger a neural impulse
• c. The all-or-none law states the size, amplitude and
velocity of an action potential are independent of the
intensity of the stimulus that initiated it
Resting Potential
• At rest the inside of the cell is at -70 microvolts
• With inputs to dendrites inside becomes more positive
• if resting potential rises above threshold an action potential starts to travel
from cell body down the axon
• Figure shows resting axon being approached by an AP
Depolarization ahead of AP
• AP opens cell membrane to allow sodium (NA+) in
• inside of cell rapidly becomes more positive than
outside
• this depolarization travels down the axon as leading
edge of the AP
Repolarization follows
• After depolarization potassium (K+) moves out
restoring the inside to a negative voltage
• This is called repolarization
• The rapid depolarization and repolarization produce
a pattern called a spike discharge
• d. The refractory period is the time during which a
neuron resists further action potentials while it
recharges
Bell Ringer 4
• How is a neuron firing like a toilet flushing? Be
sure to include the following vocabulary in your
explanation (underline each term).
–
–
–
–
–
–
Resting Potential
Threshold
Action Potential
All or none
Depolarization
Refractory Period
III. Neurotransmitters
• A. Serotonin
– 1. Affects mood, hunger, sleep and arousal
– 2. Implicated in states of consciousness
– 3. Prozac and similar antidepressant drugs raise
serotonin levels
– 4. LSD seems to act on this system
Serotonin
• B. Dopamine
– 1. Influences movement, learning, attention
and emotion
– 2. Excess activity at dopamine receptor sites is
associated with schizophrenia
– 3. Too little activity is associated with
Parkinson’s
• C. Norepinephrine
Dopamine & Drugs
– 1. Helps control alertness and arousal
– 2. Too little can lead to depression
– 3. Too much can lead to manic episodes
Norepinephrine
• D. Acetycholine
– 1. Works on neurons involved in muscle
action, learning and memory
– 2. The poison curare works by blocking ACh
– 3. Patients with Alzheimer’s show a
deterioration in this chemical messenger
• E. GABA = gamma aminobutyric acid
– 1. Serves inhibitory functions and is sometimes
implicated in eating and sleeping disorders
– 2. Also implicated in anxiety
– 3. Works with valium by increasing GABA
which decreases anxiety.
• F. Glutamate
– 1. Is the main excitatory neurotransmitter in
the brain
– 2. Some people have an adverse reaction to
MSG (Monosodium Glutamate) in Chinese
food, it tends to wind them up and make them
feel anxious
• F. Endorphins
• a. Natural pain killers in the brain
• b. Morphine is a synthetic endorphin
• c. Substance P is a neuro-cheimical that is still not
fully understood but researchers suspect that it is
involved in triggering the pain response
ENDORPHINS
• G. How drugs and other chemicals Alter
neurotransmission
– 1. Agonist work by mimicking a particular
neurotransmitter or by blocking its reuptake (or
absorption back into the body)
– 2. Antagonist work by blocking the release of
particular neurotransmitters.
The Nervous System
• A. The Central Nervous System
– 1. Also known as the CNS
– 2. It consist of the brain and the spinal cord
– 3. Cerebrospinal Fluid (CFS) is a a liquid similar to
blood serum found in the ventricles of the brain and in
the central canal of the spinal cord
– 4. The Blood-Brain Barrier is the mechanism that
keeps many chemicals from crossing from the blood
stream into the brain. This keeps most viruses out of
our brain. Certain chemicals like drugs are disolved in
fats and can cross the barrier.
• B. The Peripheral Nervous System PNS
– 1. The sensory and motor neurons that connect
the CNS to the rest of the body
– 2. It sends sensory input to the brain and relays
commands from the brain to muscles
– 3. Nerves = neural cables containing many
axons which connect the CNS with muscles,
glands, and sense organs
– 4. The PNS consists of
• a. The Somatic System = the division of the PNS
that controls the body’s skeletal muscles; AKA the
skeletal nervous system
• b. Autonomic System = the part of the PNS that
controls the glands and the muscles of the internal
organs such as the heart.
– Sympathetic Nervous System = the division of the ANS
that arouses the body, mobilizing its energy in stressful
situations
– Parasympathetic Nervous System = the division of the
ANS that calms the body, conserving its energy
The Nervous System
The Autonomic Nervous System
• Sympathetic Nervous
System
–
–
–
–
Dilates pupils
Accelerates heartbeat
Inhibits digestion
Stimulates release of
adrenaline, epinephrine
and norepinephrine
– Releases the bladder
• Parasympathetic
Nervous System
–
–
–
–
Contracts pupils
Slows heartbeat
Stimulates digestion
Contracts bladder
• C. Reflexes and Neural Networks
– 1. Reflex is a simple, automatic, inborn
response to a sensory stimulus, such as the
knee-jerk response
– 2. A simple reflex pathway also known as a
reflex arc is composed of a single sensory
neuron and single motor neuron and sometimes
an interneuron
– 3. An example of a simple reflex
• a. If you put your hand over a flame you will pull it
back before you actually feel the pain
• b. Sensory neurons in your hand send info up your
arm to interneurons located in your spine
• c. From the interneurons to motor neurons causing
your hand to pull back
• d. Finally the message will also travel up your spine
to your brain where the feeling of pain will register
– 4. Neural Networks
• a. Interconnected neural cells
• b. With experience, networks can learn, as feedback
strengthens or inhibits connections that produce
certain results.
• c. Computer simulations of neural networks show
analogous learning
Bell-ringer 4
– Write down these sentences then write down
which nervous system would be in charge of
each of these functions
•
•
•
•
•
•
sending visual information to the brain
Throwing a baseball
your personality
an increase in your heart rate during an emergency
Thinking about your boyfriend or girlfriend
Bringing the body back to its normal state.
IV. The Endocrine System
• A. The body’s slow chemical
communication system; made up of a set of
glands that secrete hormones into the
bloodstream
– 1. Transmit hormones through the blood
system as compared to the neural system
– 2. Slow, minutes or hours compared with
fractions of seconds
– 3. Long lasting, versus short lived
• B. Hormones = chemical messengers
mostly those manufactured by the endocrine
glands, that are produced in one tissue and
affect another.
• C. The Glands
– 1. The adrenal glands
• a. A pair of endocrine glands just above the kidneys
• b. The adrenals secrete the hormones epinephrine
and norepinephrine (also known as adrenaline and
noradrenaline)
• c. Helps to arouse the body in times of stress
– 2. The Pituitary Gland
• a. The endocrine system's most influential gland.
• b. Once considered the master gland
• c. located at the base of the brain near the
hypothalamus
• d. Under the influence of the hypothalamus the
pituitary regulates growth and controls other
endocrine glands
• 3. Thyroid Gland
– a. H shaped gland
located in the neck
– b. Affects metabolism
• 4. Parathyroids – help
regulate calcium in the
blood stream which is
important for
neurotransmission
• 5. Pancreas – regulates
the level of sugar in the
blood
– 6. Types of hormones
• a. Progesterone – a hormone that prepares the
uterus for the implantation of an egg.
• b. Estrogen – a hormone that is more prevalent in
females
• c. Testosterone – a hormone that is more prevalent
in males
• d. Insulin – a pancreatic hormone that facilitates the
entry of glucose into the cells
• e. Melatonin – a hormone that is closely tied to
sleep.
• f. Cortisol – a hormone that is released by the
adrenal glands which is associated with elevating
blood sugar and with stress.
• g. Epinephrine is also known as adrenaline it is also
used as a neurotransmitter
• h. Norepinephrine is a hormone that is also a
neurotransmitter
Bell-ringer
• Take out your diagram of the neuron and
study for a quiz
V. The Brain
• A. Tools of Discovery
– 1. Lesions and Accidents=
• a. Tissue destruction. A brain lesion is a naturally or
experimentally caused destruction of brain tissue
• b. Used to determine the impact on the brain functioning
• 2. EEG
– a. Electroencephalogram
– b. An amplified recording
of the waves of electrical
activity that sweep across
the brain’s surface. These
waves are measured by
electrodes placed on the
scalp
• 3. CT/CAT SCAN
– a. Computed Tomography
– b. A series of x-ray photos
taken from different angles
and combined by a
computer into a composite
representation of a slice
through the brain or body
• 4. SPECT Scan
– a. Single Positron
Emission Computed
Tomography
– b. Inject a radioactive
isotope into the blood and
examine how the blood is
moved in the brain.
• 5. PET SCAN
– a. Positron Emission Tomography
– b. A visual display of brain activity
that detects where a radioactive form
of glucose goes while the brain
performs a given task
• 6. MRI
– a. Magnetic Resonance Imaging
– b. A technique that uses magnetic
fields and radio waves to produce
computer-generated images that
distinguish between different types
of soft tissue
– c. Allows us to see structures within
the brain
CBS special on
MRI lie detection
– 7. FMRI
• a. Functional MRI
• b. Similar to the MRI but pictures are taken less
than a second apart
• c. The pictures reveal how much oxygen is being
used in each area of the brain while functioning
• d. These pictures reveal when things happen, how
the brain changes with experience and how different
areas of the brain work together
– 8. Recent findings using scanning technology
• a. PET scans show that the brain areas that light up
when people silently say the name of a animal
differs from when they say the name of a tool
• b. MRI scans of bilingual people’s brain reveal that
second languages are represented in the same area as
the first if learned early and in different areas if
learned later.
• c. FMRI scans reveal that during a rhyming task
men’s brains have a distinctively active left brain
area while women’s brains are active on both sides
• B. The basic organization
– 1. Reptilian - aka R-complex Brain
• a. Medulla, pons and cerebellum
• b. Homeostasis and instinctive behaviors
– 2. early mammalian
• a. Limbic system - hippocampus and the amygdala,
the hypothalamus and the thalamus
• b. Affective and emotional behavior
– 3. late mammalian
• a. Cerebral cortext
• b. Judgement planning etc…
• C. The Central Core
– 1. The brain stem
•
•
•
•
a. brainstem = the oldest part and central core of the brain
b. Begins where the spinal cord swells as it enters the skull
c. The brainstem is responsible for automatic survival functions
d. The hindbrain is the most posterior part of the brain it includes the
medulla, Pons and cerebellum
– 2. Medulla oblongata
• a. Medulla = the base of the brainstem;
• b. Controls heartbeat and breathing
• c. It lies directly on top of the spinal cord
– 3. Pons
– lies directly above the Medulla
– acts as a bridge between the Medulla and the rest of the
brain, as well as between the cerebral cortex and the
cerebellum
– 4. Reticular formation
• a. Reticular formation = a nerve network in the
brainstem that plays an important role in controlling
arousal
• b. Moruzzi and Magoun discovered that electrically
stimulating the reticular formation of a sleeping cat
almost instantly produces an awake and alert animal.
They also severed the reticular formation and the cat
went into a coma
– 5. The Midbrain – located between the
hindbrain and forebrain, it controls and
coordinates some basic sensory and muscle
movements.
– 6. The Thalamus
• a. The thalamus = the brain’s sensory switchboard
• b. Located on top of the brainstem; located in both
hemispheres resembling twin avocados
• c. It directs messages to the sensory receiving areas
of the cortex and transmits replies to the cerebellum
and medulla
– 7. Cerebellum
• a. The “little brain” attached to the rear of the brain
stem, to the side of the pons and medulla
• b. It helps to coordinate voluntary movement and
balance
• D. The Limbic System
– 1. Sometimes referred to
as the forebrain
– 2. The limbic system =
• a. a doughnut shaped
system of neural structures
at the border of the
brainstem and the cerebra
hemispheres
• b. Associated with
emotions such as fear and
aggression and drives such
as those for food and sex
• c. Includes the
hippocampus, the
amygdala, and the
hypothalamus
– 2. The amygdala
• a. Two almond shaped neural clusters that are
components of the limbic system and are linked to
emotion
• b. Research on aggression
– Lesions on the amygdala of an ill-tempered monkey
turned him docile (Bucy 1939)
– Stimulate one section of a cat’s amygdala and it prepares
to attack, stimulate another area and put it in a cage with a
mouse and it cowers in terror
– Has been tried on human patients with mixed and
sometimes devastating results
– 3. The Hippocampus =
• a. From the Latin word meaning seahorse
• b. Lies between the thalamus and the cerebral
cortex
• . Is linked with forming new memories
– 4. The Hypothalamus
• a. A neural structure lying below (hypo) the
thalamus.
• b. It directs several maintenance activities (eating,
drinking and body temp), it helps govern the
endocrine system via the pituitary gland and it is
linked to emotion
• c. Olds and Milner
– While trying to implant electrodes in the
reticular formation of white rats they
mistakenly implanted the electrode in a region
of the hypothalamus
– The rat kept returning to the place in his cage
where he received the electrical stimulation
– They had discovered a reward center in the
hypothalamus
– The rats would do anything to get this
stimulation, including crossing an electrified
floor. They would push the button to get the
stimulation up to 700 times per hour
– Similar reward centers have been found in many
other animals such as goldfish, dolphins and
monkeys
– When an electrode was planted in violent
patients they reported mild pleasure but were not
driven to frenzy like the rats
– Reward deficiency syndrome is genetic disposed
deficiency in the natural brain systems for
pleasure and may lead to such disorders as
alcohol and drug abuse
Olds and Milner Study
• E. The Cerebral Cortex
– 1. Physical description
• a. Convolutions increase the surface area of the
brain
• b. Gyri = rolls that form the folding out portion
• c. Sulci = valleys
• d. Fissures are deeper than valleys
The Cerebral Cortex
– 2. The four lobes
• a. Frontal lobes
– The portion of the cerebral cortex lying just behind the
forehead;
– Involved in speaking and muscle movements and in
making plans and judgments
– prefrontal cortex receives sensory information from all
senses
• b. Occipital lobes
– The portion of the cerebral cortex lying at the back of the
head;
– Includes the visual areas, (V1 & V2) which receive visual
information from the opposite visual field
– cortical blindness is a specific type of blindness due to
brain damage
• c. Parietal lobes
– The portion of the cerebral cortex lying at the top of the
head and toward the rear;
– Includes the sensory cortex
– specializes in processing body information such as touch
and body location
• d. Temporal lobes
– The portion of the cerebral cortex lying roughly above the
ears;
– Includes the auditory areas, each of which receives
auditory information primarily from the opposite ear.
– One of the key areas of speech known as Wernicke’s Area
is located in this lobe
– 3. Motor Functions
• a. The motor cortex = an area at the rear of the
frontal lobes that controls voluntary movement
• b. Foerster and Penfield mapped the motor cortexes
of wide awake patients by electrically stimulating
portions of the motor cortex and noting the body
responses
• Delgado illustrated this by making a monkey smile
and forcing a patient to make a fist
– 4. Sensory Functions
• a. The sensory cortex = the area at the front of the
parietal lobes that registers and processes body
sensations
• b. The more sensitive the body region the greater
the area dedicated to this body part.
• c. Examples include; if you lose a finger the area
dedicated for that finger will reorganize itself to pick
up sensations from neighboring fingers
Motor and Sensory Areas
– 5. Association Functions
• a. Association areas = areas of the cerebral cortex that
are not involved in primary motor or sensory functions
• b. Rather they are involved in higher mental functions
such as learning remembering, thinking and speaking
• c. Examples of association area damage
– Wilder Penfield’s sister had damage to her frontal lobe, and
although she had perfect knowledge of cake recipes could not
bake a cake.
– Phineas Gage was a railroad worker who suffered sever brain
damage. As a result his limbic system (emotional center) was
seperated from his frontal lobe (planning center) He was now
irritable and quick to be angry
– 6. Language
• a. Aphasia = impairment of language usually caused
by left hemisphere damage either to Broca’s area
(impairing speaking) or to Wernicke’s area
(impairing understanding).
• b. Broca’s area = an area of the frontal lobe usually
in the left hemisphere
– It directs the muscle movements involved in speech
– Discovered when Paul Broca treated his famous patient
“Tan”
• c. Wernicke’s Area = a brain area involved in
language comprehension and expression; usually
found in the left temporal lobe
• e. Geschwind’s
description of how we
read aloud
– The visual cortex in the
occipital lobe receives
written words as visual
stimulation
– The angular gyrus
transforms the visual
representations into an
auditory code
– Wernicke’s area interprets
the auditory code
– Broca’s Area controls the
muscled for speech via the
motor cortex
– The motor cortex signals
the appropriate muscles to
make speech
GHOTI
– 7. Brain Reorganization
• a. Plasticity = the brain’s capacity for modification
as evident in brain reorganization following damage
(specifically in children) and in experiments on the
effects of experience on brain development
• b. Examples include a man who had ½ of his brain
removed and yet made it through college and grad
school.
VII. Our Divided Brains
• A. Splitting the Brain
– 1. Sperry and Myers used classical conditioning to
train a cat while one eye was closed. When tested with
the opposite eye open the cat was unable to produce the
newly learned behavior. The study showed that the cat
must be conditioned for both eyes.
– 2. Vogel and Bogen were two neurosurgeons who
proposed splitting the brain of one of their severely
epileptic patients, a 48 year old war veteran referred to
as W.J.
Split Brain Experiment
– 3. Upon awakening the patients seemed to be
fine able to think and function normally.
– 4. Roger Sperry invented an apparatus to study
the split brain patients. This apparatus involved
flashing different words to each visual field
while also allowing for the patient to blindly
feel objects with both hands.
– 5. The subject is asked to fixate on the center
of the screen while words are flashed very
briefly onto the screen. The subjects were then
asked to identify vocally and with their hands
what they saw.
– 6. When intact brain patients participate they have no
trouble identifying the word “key ring”
– 7. Split brain patients on the other hand report only the
word “ring” which was presented in their right field of
vision which is processed by the left brain which is also the
verbal side of the brain.
– 8. If asked to identify the object with their left hand
(controlled by the right brain) they will search for the key
that they would adamantly deny seeing.
– 9. One way they can compensate is by saying the word out
loud so both sides become aware of it or by pointing to
communicate between the right and left hemispheres
– 10. The results may have been over-generalized to the
fields of education and literature.
• B. Studying Hemispheric Difference in the
Intact Brain
– 1. Perceptual task are centered in the right
hemisphere
• a. For example most people recognize a picture
more quickly when it is projected to the right brain
• b. Although the left brain is better at recognizing
words the right brain is better at identifying abstract
relationships between words
• c. Faces are recognized in the right brain
– 2. Language tasks are generally centered in the
left hemisphere
• a. For example most people recognize words more
quickly when flashed to the left hemisphere
• C. Brain Organization and Handedness
– 1. Handedness and language
• a. About 95% of right handers process language in
their left brain
• b. Left-handers are more diverse
– More than half process language in their left hemisphere
– About 25% process language in their right hemisphere
– And the other 25% process language in both hemispheres
– 2. Is handedness inherited
• a. Right handedness goes back to prehistoric times
• b. Ultrasound shows that 9 out of 10 babies in the
womb show a preference for sucking the right
thumb
• c. Handedness is one of the few characteristics
identical twins often do not share
– 3. The Case of the Disappearing Southpaws
• a. Studies show that left handers die earlier than
right handers
• b. May be due to prenatal stresses and premature
births
• D. Hemispheric specialization
– 1. Left Brain specialization (analytic)
• a. Language
– Wernicke’s Area = left temporal lobe = normal speech
without structure
– Broca’s Area = Left frontal lobe = expressive area =
trouble putting speech into words
• b. Mathematical
– 2. Right Hemisphere specialization (creative)
• a. Spatial functions
– Pattern recognition such as faces
– Color discrimination (fine differences)
• b. Musical
– Variation in intonation
– Memory of musical patterns in right side
VIII. Genetics and Environment
• A. Our Biological Blueprint
– 1. Chromosomes = Thread like structures made
of DNA molecules that contain the genes
– 2. DNA = a complex molecule containing the
genetic information that makes up the
chromosomes
– 3. Genes = The biochemical units of heredity
that make up the chromosomes
– 4. Genome = The
complete instructions
for making an
organism, consisting of
all the genetic material
in its chromosomes.
• B. Evolutionary
Psychology
– 1. The case of the
tame fox
• a. Researchers in
Russia selectively bred
foxes to create a tame
fox that was completely
domesticated
• b. Some 45,000 foxes and 40 years later, they have
created a fox that can be a pet, replicating what may
have happened between our ancestors and wolves
that later became man’s best friend.
• c. This shows that certain traits can be inherited and
selected for survival
– 2. Natural Selection
• a. The principle that among the range of inherited
trait variations, those that lead to increased
reproduction and survival will most likely be passed
on to succeeding generations
• b. Mutation = a random error in gene replication
that leads to change in the sequence of nucleotides –
the source of all genetic diversity.
– 3. Evolutionary Psychology = the study of the
evolution of behavior and the mind, using
principles of natural selection.
• a. Natural selection has favored genes that designed
both behavioral tendencies and information
processing systems that solved adaptive problems
faced by our ancestors.
• b. Thus contributing to the survival and spread of
their genes.
– 4. Evolution and sexuality
• a. Gender = in psychology the characteristics
whether biologically or socially influenced by which
people define males and females.
• b. Sexuality especially attitudes towards sex is one
of the greatest differences between the genders
• c. Evolutionary
psychologist would
say that the fact that
women nurtured the
child, caused this
difference
– Women mated wisely,
while men mated
widely.
– Men are attracted to youthful women whose waist is three
times as small as her hips – suggesting child rearing.
– Women were attracted to healthy looking men, but
especially those who seem mature, dominant bold and
affluent.
– 5. Critique of the Evolutionary Perspective
• a. Starts with a behavior and works backwards so it
could be tainted by hindsight bias
• b. Others say it will lead to a type of determinism
and loss of free will.
• C. Behavior Genetics
– 1. Behavior Genetics = the study of the relative
power and limits of genetic and environmental
influences on behavior.
– 2. Environment = every nongenetic influence
from prenatal nutrition to the people and things
around us.
• 3. Twin Studies
– a. Identical twins =
twins who develop
from a single fertilized
egg that splits in two
creating two
genetically identical
organisms
• b. Fraternal twins = twins who develop from separate
eggs. They are genetically no closer than brothers and
sisters, but the share fetal development
• c. Twin and Adoption Studies
– Many cases of twins who have been separated at birth and
raised independently have been study to reveal the relative
importance of both genetics and environment.
– The findings although criticized by some show many
startling similarities.
– With adoption studies we look at siblings who were
separated at birth and raised independently.
– The findings point to the importance of genetics over
environment.
– 4. Heritability = the proportion of variation
among individuals that we can attribute to
genes. The heritability of a trait may vary,
depending on the range of populations and
environments studied.
– 5. Molecular Genetics = the subfield of biology that
studies the molecular structure and function of genes
• D. Genetics and Human Disorders
– 1. The X Chromosome – in humans females most often
have two x-chromosomes, while men only have one
– 2. The Y Chromosome – in humans males have on Ychromosome whereas women have none
– 3. Genetic Disorders
• a. Down Syndrome –
usually with 3 copies of
chromosome 21 in their
cells, individuals are
typically mentally
retarded, have a round
head, flat nasal bridge,
protruding tongue,
small round ears, a fold
in the eyelid and poor
muscle tone and
coordination
• b. Albinism = a recessive trait that produces lack of
pigment and involves quivering eyes and inability to
perceive depth with both eyes
• c. Hunnington’s Disease – a dominant gene defect
that involves degeneration of the nervous system
characterized by tremors, jerky motions, blindness
and death
• d. Klinefelter’s syndrome – males with XXY
chromosomes – often results in taller, leaner men
with less bone density and muscle strength
• e. PKU – phenylketonuria is a recessive trait that
results in severe, irreversible brain damage unless
the baby is fed a special diet low in phenylalanine
• f. Tay-Sachs syndrome – Recessive trait that
produces progressive loss of nervous function and
death in a baby.
• g. Turner’s Syndrome – females with only one X
chromosome. They are usually short, often sterile
and have difficulty with calculations.
IX. Environmental Influence and
Genetics
• A. Culture
– 1. Culture is the enduring behaviors, ideas,
attitudes and traditions shared by a large group
of people and transmitted from one generation
to the next.
– 2. Norm = a norm is an understood rule for
accepted and expected behavior. Norms
prescribe “proper” behavior
– 3. Personal Space = the buffer zone we like to
maintain around our bodies
– 4. Memes – Self replicating ideas, fashion and
innovations passed from person to person.
• B. The Nature and Nurture of Gender
– 1. Role = A set of expectations about a social
position.
• 2. Gender Role = a set of
expected behaviors for
males and females.
• 3. Gender Identity –
one’s sense of being
either male or female
• 4. Gender Typing – the
acquisition of traditional
masculine or feminine
roles
– 5. Social Learning Theory = the theory that we
learn social behavior by observing and
imitating and being rewarded or punished.
– 6. Gender Schema Theory = the theory that
children learn from their cultures a concept of
what it means to be a male and female and that
they adjust their behavior accordingly.
Prompt 7:
• Draw a brain and label the structures of the
cerebral cortex.
Essay Question 1
• Describe the structure and function of the
various parts of a neuron. Explain the
process involved when a neuron goes from
a state of rest to communicating with
another neuron.
Bell-ringer 10
• Get a text book out of the closet and then
label the two brain worksheets.
Links
The Teen Brain