PSY460
Biological Bases
of Behavior
Introduction to the Class
Chapter 1:
The Major Issues
• Mind-Brain Relations
• Nature & Nurture
Slide 2: The Syllabus
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Class & Labs- where and when
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Reaching me & office hours
Resources
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 The web page & resources
 Textbook & Annual Editions
 Laboratory Assignments
 Nature of lab assignments
 Late Assignments
 Grade Scale- a point system
 Participation
 Class/Lab Participation
 Research Participation
Slide 3: Intro to Biological Psychology
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Phineas Gage- Film
Biological Psychologythe study of behavior and experience in terms of
genetics, evolution and physiology (esp. nervous
physiology… i.e., the brain and autonomic nervous
system).
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Names of Scientists of the field
Physiological psychologist
Biopsychologist
Behavioral Neuroscientist
Neurologists
Slide 4: Explaining Behavior and Experience
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What is the job of psychology? Explain/Understand
Behavior and Experience
Biopsychology (4 approaches to explanation)
Physiological explanation- explanations for psychology
at the level of the the brain, organ structures and
biochemical interactions.
Ontogenetic Explanations- contribution of genes,
nutrition and experience on behavior (alcoholism).
Evolutionary Explanation- where (ancestors) the
behavior evolved from (e.g., piloerection)
Functional Explanation- how is behavior of a functional
value (useful) for survival (reproduction) (e.g., greed).
 Sociobiology (aka evolutionary psychology) = evolution of
social behavior
Slide 5: Consequences of Biopsychological
Perspective
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A conscious understanding of “reasons” for behavior
are not necessary to explain behavior!
We act because of nervous system wiring
We act because of genetic make-up
 could you ask someone to explain the reasons for
their eye-color?
We act because of a distant ancestor did the same
 “fight/flight” activation to threat
We act because it has served us in the past to survive
and reproduce.
 Jealousy, greed, helping, altruism, aggression
Slide 6: The Brain & Conscious
Experience
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Biological Psychology- An ambitious field….
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PHILOSOPHIES OF EXISTENCE:
The mind-body problem: what is the relation between mind
and the body?
Dualism (2 kinds of existence)
Monism (1 kind of existence)
 Material Monism
 Mental Monism
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METHODOLOGICAL LEAPS OF FAITH:
The problem of minds- How can we know others really
experience what we do?
 Solipsism- “I alone am conscious/exist”
 Non-solipsists- can know by reason and analogy
– but how far can you go…Monkeys, rats, roach, amoebas???
Slide 7: Summary
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Our experiences and behaviors certainly exist.
Biopsychologist attempt to explain these most
frequently in terms of physiological and genetic
processes.
“The physiology of human experience
 consciousness
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What to expectmechanistic explanations
evolutionary (rather that cultural) explanation
references to animal research
the grounds of much of our experience (“body”)
Slide 8: The Language of Genetics
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“We should not be amazed that almost every human
behavior has some heritability (effected by genetic
influence)” But how much is nature vs. nuture????
Gene- a physiological unit of heredity that
maintains its structural identity from one generation
to another. (come in pairs) ---Examples?
Chromosomes- strands of genes (23 pairs)
Chromosome is Homozygous for a gene
 identical pair of genes on each chromosome pair
Chromosome is Heterozygous for a gene
 unmatched pair of genes of each chromosome pair
Slide 9: Language of Genetics (cont.)
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Dominant Genes (A)- genes that show a strong effect in
either the homozygous and heterozygous condition
Recessive Genes (a)- genes that show its effect only in
homozygous conditions.
Homozygous pairings= AA (dominant trait expressed)
or aa (recessive trait expressed)
Heterozygous pairings= Aa or aA (dominant expressed)
Common Example of and inherited trait: Taste and PTC
 Dominant Gene- (T) can taste in moderate concentrations
 Recessive Gene- (t) can taste only in high concentrations
» (overhead 1)
Slide 10: Passing on Traits
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Quick & Dirty Exercise-gene for “ticklishness” (somatic sensitivity)
 “A” (dominant)- highly sensitive to tickling
 “a” (recessive)- modestly sensitive
SCENARIOS:
 Parents- Aa and Aa
 Parents- AA and aa
 Parents- aA and AA
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What is the chance that their child will be highly sensitive
in each case? If there are 4 children in each family, what
is the likelihood of a hetero- or homozygous gene
pairing?
Slide 11: Gene Expression…if the conditions
are right!
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Simple results of a dominant/recessive gene
combinations
 Eye color, Hair color, toes and finger size etc etc….
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More complicated cases involve combinations of other
genes & environmental conditions to produce their
effect.
 Partial Penetrance- genes expressed (penetrate into one’s life)
only under certain conditions.
 Genes and Alcohol risk- expression only apparent in
certain environments.
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Sex-Linked Genes- genes found exclusively on the
male/female chromosomes
 “X”- the female chromosome- loaded with genes (Rs & Dom)
 “Y”- the male chromosome- virtually w/o genes..X is default
 XX = female
XY= male (fem. genes expressed)
Slide 12: Sex Linked & Sex Limited Genes
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Red-Green Color Blindness- a condition that
results from combination on the sex chromosomes
text example (not actual number)
 if 8% of women had recessive RG gene then 8% of all
men but only 1% of women would be color blind
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Sex-Limited Gene Expression- expression
effects only one sex or it has a much stronger
effect on one sex.
 examples- location of hair growth, breast growth
Slide 13: Sources of Variation
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Why aren’t we clones of one another?
Recombination - receiving new combinations of genes
from our parents..
– They might be Aa and Aa
– We might be AA or aa or Aa
Mutation- a random change in a single gene . A gene
for blue eyes-- become one for brown.
 Usually recessive, therefore rarely harmful because
both parents would have to have recessive mutation to
have gene expressed.
 Unless… “inbreeding” occurs. Why???
– Hemophilia (the disease of czars)-- Romanov Family
Slide 14: Measuring the Contribution of Genes
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Heritability- estimate of variance (effect) due to heredity.
 Scale- 0 to 1.
 e.g., .15 = low .85 = high heritability
 PKU = 1, gene combination inhibits phenylalanine.
 Key Point- in the cases of looking at the heritability of behavior,
one cannot speak only only of genes or environment. Behaviors
are clearly affected by both (while the contributions of each may
not be be equal.
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Measuring Heritability (of Depression, for example)
 Identical Twin Studies compare identical twin to fraternal twins
 Adoption Studies
 are children more like adopted or biological parents?
Slide 15: Genes affecting Behavior
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“They have a Gene for….” (depression in text)
KEY POINT: Genes don’t directly affect
behavior
 genes affect physiological processes by affecting
protein production which affect chemical production
(for example).
 Depression (factors which affect serotonin or NE use
at the neuronal level)
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Even more indirect routes
 limitations of physiology due to genetic building
– Dr. Craig = Michael Jordan? Ever? Nope!
Slide 16: Evolution of Behavior
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Evolution- the changes over many generations of
the frequencies of various genes in a population.
How did we evolve (from where?)
 evolutionary tree
 98% shared genes with chimpanzee
How do species evolve (process of change)
 natural (vs. artificial) selection
– Characteristics that lend themselves to survival assist an
individual in surviving to reproductive age, therefore these
“survival” genes are passed on to the next generation
 Process- mutations and recombination make animal more
or less able to reproduce.
Slide 17: Misunderstandings of
Evolution
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Evolution=Improvement?
Maybe, maybe not… dependent on environment of the
time… (e.g., peacock..)
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Have human stopped evolving?
No. As long as we reproduce we evolve
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Lack or excess use lead to change in that use area?
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(Lamarkian Evolution,… giraffe, lil’toe)
Not one that will be passed down to children
Does evolution act to benefit individuals/species?
Neither… it is a neutral event in which genes live on, but
not you or necessarily the species as you know it.
Slide 18: Sociobiological Example:
Evolutionary Explanations of Altruism
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Sociobiology- the study of the evolution of social behavior
 Functional explanations
 Criticisms of the field
 Functional explanations are often speculative
 Sociobiological explanations sometimes imply that human behavior has
evolved to be as it is, and therefore it should stay that
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Altruistic Behavior
 animal behaviors
 human behavior
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Class Discussion of the evolutionary and functional explanations
for “Altruism”
– (exercise?? See “Stop & Check” on pg. 16)
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Common Explanations & Rebuttals
 reciprocal altruism
 kin selection
Figure: Genetic combinations/outcomes
[BACK]
Figure 1.7 Four equally likely outcomes of a mating between parents who are heterozygous for a
given gene (Tt)
A child in this family has a 25% chance of being homozygous for the dominant gene (TT), a 25% chance
of being homozygous for the recessive gene (tt), and a 50% chance of being heterozygous (Tt).
Slide 20: