Transcript IB Chapter 2: Biological Level of Analysis

IB Chapter 2: Biological Level
of Analysis
IB Psychology
Ms. Freeman
“To what extent do
genes influence
behavior?”
• Genes are the building blocks of behavior
and influence behavior to a certain extent
• Genes CAN’T affect behavior unless they are
expressed
• Epigenetics– how factors such as parenting and
stress affect the expression of genes
• Positive parenting, stress reduction, exercise may prevent gene expression
for unwanted behaviors such as depression
• Gene Environment Correlation– how genetic
differences between people shape the way the respond
to their environment
“To what extent do genes influence
behavior?”
• Cultural Neuroscientists– how cultural
differences in genetics are correlated with
cognitions and emotions
• Twin
and Adoption studies use the behavioral
genetics method
•Reveal some genetic contribution to behavior, but nothing about specific genes
• Twin studies reveal that genetics account for about 50% of schizophrenia; leaves
a lot of room for environmental factors such as stress
• Molecular Genetics– specific genes related to behavior
3 approaches to studying specific
genes
1) Linkage Studies– find a direct linear relationship
between gene and behavior
•Linear Approach– genes directly cause behavior
2) Endophenotypes—how hormones and NT are
related to behavior; such as aggression and depression
3)Gene Environment-- correlations includes
environmental factors in genetic study.
“How does an environmental factor, external to the person get inside the NS
and alter its elements to generate the symptoms?”
3 Ways genes and the environment
become correlated
1) Passive gene- environment– parents contribute
genes and provide environment
2) Active gene- environment– child may select certain
environments; select peer group that enhances
aggressive delinquent behavior
3) Evocative gene- environment– child with a
particular temperament might help create their own
environment by encouraging abusive behavior from
already hostile or rejecting parents
Depression: Stress Hormone, NT,
and Genes
• Glucocorticoids (Stress
hormone) are secreted any time
we experience flight or fight (jump
out of the way from a car)
• Most stressful events are imagined stress, anticipating
real or imagined stress effects your body
• People who frequently worry about imagined stressors
have their flight or fight constantly activated
HPA Axis: Hypothalamic PituataryAdrenal Axis
• HPA Axis helps regulate temp, digestion, immune
system, mood, energy use
• helps control your reaction to stress, trauma, and
injury
• Constantly activated it can weaken immune system,
impair memory, shrink hippocampus, increase risk for
depression
• HPA helps you jump out of the way, there should be a
mechanism to reestablish a normal level; however this
deactivation appears to be deficient in depressed people
• Remember: Depressed people have increased levels of Glucocorticoids
Depression
• People with depression have a malfunction with
their NT system
• Chronic increased levels of stress hormones can alter
the structure and function of serotonin, dopamine, and
norepinephrine
• Stress affects the release and breakdown of serotonin and depletes the amount
of dopamine in pleasure center
• Depressed people have a smaller hippocampus which
is part of the limbic system ,which is responsible for
emotion regulation and some memory
Depression in the Brain
• Cortex layer above the limbic system,
cortex tells the limbic system that life is
threatening
• ACC is related to emotion; only activates when people think about emotions
• PFC (Prefrontal Cortex) is in front of the ACC; responsible for positive and
negative emotions
•Left side= Positive; Right= Negative
• Depressed people have decreased left and heightened right,
hippocampus is bombarded with stress
• Cells in the hippocampus have receptors and long term exposure means
glucocorticoids can bind to cells and change them, possibly permanently
Women and Depression
• Lower Social Statuses
• More social Stressors
•Experience more childhood sexual assault
•Place less emphasis on own needs, more
vulnerable to depression when relationships end or
in trouble
• Ruminate more often, increase risk for depression
Examine one evolutionary
explanation of behavior
• Evolutionary Psychologists believe:
1) Brain is a system with circuits to generate behavior that best fits with one’s
environment.
2) Natural selection designed these circuits to solve problems faced by our ancestors.
These circuits are not designed to solve any problem, just adaptive problems.
Language is a good solution to evolutionary problem related to communication
3) People are not conscious of all the brain’s workings. You are only aware of the end
problems, such as a sentence you speak, and not everything that goes on to construct
the sentence
4) Different neural circuits are specialized for solving different adaptive problems. For
example, babies come into the world with evolved circuits that allow them to pay
attention to faces
5) Natual Selection took a long time to design brain circuitry, so our modern minds are
similar to ancient minds. Our minds did not evolve in modern societies. Rather, our brain
lived most of its evolutionary existence in hunter- gather socities
Patricia Kuhl and Language
• Babies come into this world with evolved skills that
helped them learn their culture’s language
6 components of innate learning process
1) Infants have the innate ability to perceive the basic units of speech. Infants do
not understand the meaning of the sounds; they just have an innate ability to
discriminate between them
2) A child’s language development is not selectionist. Older theories suggest that
as children develop. They lose the ability to hear sounds that are not relevant to the
primary language of their culture. However, current research shows that adults could
discriminate the sounds of other languages under certain conditions, such as extensive
training
3) Babies use learning strategies that map language rules. First they detect patterns
in language. Second, studies using artificial words show that infants are now able to
group together sounds that are typically linked. Third, child’s perception becomes fine
tuned. One sound becomes a prototype, meaning the sound is an example of other
sounds that are similar.
Patricia Kuhl and Language
4) Children learn to become native speakers of the culture’s language.
5) Use of infant- directed language. Infant- directed language is done unconsciously
and helps babies map out the sounds and rules of language.
EX: “See the ______” and “Where is the ______”
6) Critical period for language development. Ability to learn language later in life may
be constrained be the initial mapping involved in learning one’s native language. It is
easiest to learn a second language when both are heard during the time when innate
perceptual abilities are tuning into the sounds and then acting as magnets for other
related sounds
Explain the Functions of Hormones
in Human Behavior
• 2 most important hormones:
Stress Hormone: Cortisol, the most important of the glucocorticoids
Sex Hormones: Estrogen and Testosterone
**REMEMBER:
Both are steroid hormones and can influence the transcription process of genes.
Hormones contribute to the differences between males and females on some cognitive
tasks
What role do sex hormones play on gender
differences?
Gender Differences (Kimura)
• Hormones organize male and female
brains differently
1) Prenatal and developmental sex hormones are important factors for spatial ability
2) These difference appear early in life before social factors influence behavior
3) The difference exists across culture
4)The differences do not change when females receive extensive training as adults
5) The performance has not changed over time for the highest levels of mathematical
reasoning
6) Animals show the same sex differences in spatial performance
Specific Differences in Spatial
Performance (Kimura)
1) Males perform better on some spatial tasks, particularly mental
rotation, mechanical reasoning, and throwing accuracy
2) Females perform better on tasks of verbal memory and object location memory
3) Males are favored on mathematical reasoning and spatial visualization tasks
4) Females perform better on verbal fluency and perceptual speed tasks
Read Kimura’s Studies
Male vs. Female Brain
- Males have higher percentage of white matter and females have
higher percentage of gray matter
-Gray matter in the frontal cortex and occipital region peaks earlier
in females
- White mater increases in both males and females from 4-22, but
a higher rate for males. The longer development time in males is
correlated with spatial performance
- Corpus Callosum larger in females; the splenirum (a part of the
corpus callosum) may give females an advantage in their verbal
abilities.
- Males have a larger midsection of the corpus callosum, which is used in motor
coordination. This can be related to better spatial abilities
Men vs. Female Brain
- Females have higher rates of resting cerebral blood flow
- Females have higher activation in both hemispheres when
completing language tests
Is it reasonable to conclude that brain differences
are partially responsible for gender differences in
cognitive abilities?
Discuss 2 Effects the Environment
on Physiological Processes
Neuroplasticity– brain has the ability to change; experiences that
affect neuroplasticity are stimulating environments, sex
hormones, diet, genetics, and stress
-As behavior changes there must also be a corresponding change in the neural circuitry
that produces behavior
- Occurs over lifespan
- Behavior changes occur after neuroplasticity changes
- The brain can reorganize itself after injury. The brain spontaneously reorganizes itself
right after injury so this is the best time for treatment
Neurogenesis– new neurons are created in response to experience
Research: John Kolb– compared rats in an enriched environment versus a standard
cage
Enriched environment had increase in dendrites and neuron spine density
**pg 219 Research
Explain the effects of
Neurotransmission on Human Behavior
“You are what you eat”
• Food impacts how NT function in the
brain, which affects behavior
• 70 NT regulate nerve
functioning and contribute to
normal mood, memory, and
sleep patterns
Serotonin
• Monoamine
•Synthesized from essential amino acid called tryptophan (Bodies don’t produce it)
• Strongly linked to your diet
• Most serotonin is in the GUT!!!!; after synthesized it is carried to the brain
•Low levels are linked to Depression
Explain the effects of
Neurotransmission on Human Behavior
To much carbs and fatty foods contributes
to depression by making NT under or
over active.
Lack of nutrients, such as zinc and protein, can
potentially cause irreversible damage to the NS,
effecting mental function and personality
Explain 1 study Related to Localization
of Brain Functioning in the Brain
• Bilingualism: Acquiring 2 languages on or before age 6
stimulates more and different pathways than in children who
speak just 1 language and in people who acquire a second
language after age 6
Hull and Vaid came up with 4 Hypotheses
1) Second Language Hypothesis– bilinguals use more of the right brain
2) Balanced Bilingual Hypothesis– proficient bilinguals are more right brain lateralized
than monolinguals
3) Age of Second Language Hypothesis-- close in time 2 languages are acquired, the
more similar the brain localization
4) Stage of Second Language Hypothesis– early stages of learning a second
language depends largely on contextual cues, which are localized in the right
hemisphere. The left becomes more dominant as the person becomes more proficient
with the second language and it is processed in a way similar to the first
Hull and Vaid Findings
1) Monolinguals and Bilinguals who acquired their
second language after age 6 showed the most
left hemisphere dominance. This was the most
striking finding and supports the Second
Language Hypothesis
2) Early Bilinguals were bilateral. This supports
the Second Language Hypothesis
3) There was NO significant hemispheric
localiztaion differences between the proficient
and non- proficient bilinguals.
Discuss the Use of Brain Imaging Technologies in
Investigating the Relationship between Biological
Factors and Behavior
fMRI Advantages
• Most hospitals already have MRI scanners
so they were easily converted into fMRI
• Higher spatial resolutions of 2 to 3 cubic
millimeteres
• Doesn’t require radioactive injection
• Localizing brain activity is easier
• Takes only 1 to 2 minutes to scan most of
the brain.
• Isolate BOLD ( blood-oxygen- leveldependent); blood releases oxygen to active
neurons faster than to inactive neurons
Discuss the Use of Brain Imaging Technologies
in Investigating the Relationship between
Biological Factors and Behavior
fMRI Limitations
• Ethical Concerns: How should this info be used,
how accurate, invade privacy?
• How accurate? fMRI measures blood flow changes
during cognitive tasks
• Blood flow is an indirect way to view neuron
activity. Blood flow in the brain is fairly slow;
starting about 2 secs after neural activity starts
and hits the highest point between 5-7 seconds.
Thus the image is recorded more slowly than
actual neural activity.
• some neurons are important to a cognitive task may not draw as much blood as
other neurons or may use little blood because ther are more efficient. Scan might not
detect important neuron activity
• As a result of accuracy and legitimacy problems, there is a lot of room for error.
Sometimes fMRI images are over interpreted. ( Read examples)