Genetic Factors Flashcards
what is behavioral genetics?
quantitatively oriented science that estimates relative contributions of both heritable and enviro factors to human behavior
who was the first to study heritability of non-physical phenotypic features?
Galton
the expression of one phenotype over the other results from _____
dominance or incomplete dominance
what is polygenic?
characteristics of interest - influenced by multiple genes
intellectual functioning can be influenced by genes that regulate what?
NT function
cerebral morphology
blood flow
-> high correlation
does behavioral genetics imply determinism?
no but born with predispositions
- not imply absolute control by geens
what is h^2?
heritability
- ratio of genetic variance to phenotypic variance
- what portion of the observed trait’s expression can be created by genetic factors
what does 0 and 1 mean for h^2?
0 = no identified genetic contribution
1 = all variance is genetically based
what does heritability do?
estimates how important genes are to the expression of a given trait
h^2 is based on who?
whole population
- variable
- heavily dependent on measurement approaches used to assess given trait
what is s^2?
- variance
- quantifies amount of spread in given population but there is variability
variance accounts for what?
individual or group differences
- great or small
what did Buss say about h^2?
it is never 0 in psychology
what is genotype?
alleles possessed by an individual organism
what is phenotype?
manifested characteristics of organism
what is polygenic determination?
several genes contribute to expression of a certain characteristic
is h^2 constant over time?
no
- total variance in any trait can change and so can h^2
- it is about genetic differences between one organism to another
what are the 2 types of enviro effects?
c^2 and e^2
what is shared enviro?
c^2
- aspects encountered by all members of a certain group
- full siblings raised by bio parents
what are non -shared?
encountered uniquely
what is epigenetics?
study of changes in expression of genes that do not result from alteration in sequence of genetic code
how do genes get switched on and off?
in response to enviro factors
what is DNA methylation?
- methyl groups attach to certain pieces of DNA which affect a gene’s expression
-> prevents combination of genes
SLC6A4
serotonin transporter gene
- lower 5-HT = increased aggression
- hypermethylation = lower 5-HT synthesis
- correlates to depression and anxiety
OXTR
oxytocin transporter gene
empathy and emotional reg
- low hostility
- antisocial
MAO-A promoter
monoamineoxidase promoter
- initiates transcription
- hypermethylation = increased aggression and ASPD
- most direct lane
DRDI
dopamine receptor gene
- more methylated in aggressive boys
- lower exec fxn and cog
KEY**: what is evocative style?
mom is closer to younger sister bc spends more time with her so the influence she exerts on your behavior is different than those on your younger sister
-»> it is the way we bring out things in other people
-> reactions
what are gene effects confounded by?
environment effects
- the effects of one are hard to differentiate from another
- if one sib has a convinction the other highly likely does too if they are raised in the same enviro bc of evocative style
how can h^2 be estimated by examining correlation between MZ and Dz twins?
h^2 = 2(rMZ - rDZ)
rMZ = 0.87
rDZ = 0.72
what did Lykken write about h^2 and c^2?
h^2 = 0.3-0.4 range
c^2 = 0.3 but decreases over lifespan as e^2 and h^2 increases
what influences h2 and c2?
parental control/influence decreases
total variability increases
what is much higher for component traits?
h2
- aggression
- fearless
- IQ
- impulsive
- sensation seeking
Mednick study purpose and results
- intension is to separate heritability from enviro
- neglect e2
- wanted to follow children adopted from and into both criminal and non-criminal families
- interaction effect
- effect of bring reared by criminal parents is more influential if there is a bio predisposition than enviro effect
problems with adoption studies?
decreases variability to well below random levels which artificially suppress e2 estimates if r = 0
- higher proportion of observed variance stems from heritable contributors
KEY: how is criminal behavior best understood?
in terms of interaction between genetic and environmental factors
having both factors is worse outcome than individual effect
what is cNS model?
is it a bridging model
- theory about fxn of CNS and able to accommodate existing data
- marries 2 separate areas of inquiry
- brain and behavior - psych and physical
- can emphasize diff aspects of learning (AS behavior)
what did Eysenck do?
ARAS levels - high level of between-subject variance
- receive input from most major sensory systems
- sleep-wake transitions and lvl of cortical arousal
- influence more fundamental processes
what are the differences in ARAS determined by?
genetics
Ascending Reticular Activating System
- differences in orthogonal dimensions (UNCORRELATED) of I-E, P, N
I-E, P, N
introversion-extroversion: interaction
psychoticism: ability to accept other perspectives and opinions
neuroticism: instability vs stability
what does I-E, P and N influence?
pre-disposition and one’s tendency to engage in criminal behavior
- moderator variable
low ARAS = ?
antisocial -> criminal
altruistic -> heroic
what did Eysenck present?
evidence that prisoners score higher on NP than controls
- greatest hypothesized differences (I-E) were small
what does P represent in prisoner terms?
autism and lack of empathy and meotion
I-E axis matters for what?
what type of crime
Gray’s model based on _____
septohippocampal sys
- deals with organism’s responses to CS
BAS
behavioral activation system - approach
BIS
behavioral inhibition system
- avoidance
NAS
non-specific arousal system - vigor of response
what are BAS and BIS operating on?
basis of reciprocal inhibitoon
BAS and BIS can do what?
increase NAS
- amount of energy increases
what is BAS sensitive to?
reward and active avoidance
what is BIS activated to?
by cues for punishment and non-reward
- re-focus attention toward other cues
what does NAS modulate?
intensity of behaviors triggered by both systems
difference between active and passive avoidance?
passive avoid trouble by not doing that thing
active is that actively avoid some neg experience
How is BAS activated?
input of signals of reward
goes to decision mechanism to approach to motor system
- BAS + NAS
BAS - BIS
how does BIS work?
input signals of punishment
BIS
decision
stop and inspect to motor
BIS + NAS
BIS - BAS
how does Gray’s model explain criminal behavior?
criminals seen as imbalance
- BAS predominates - too amped up
- BIS fails to inhibit goal-oriented behavior in presence of certain cues
what does the model fit well with?
deficient passive avoidance learning
high aggressiveness - goal oriented
low anxiety
impulsivity
what can TBI’s do?
onset of illness mark emergence of highly antisocial aggressive behavior
- more freq in those who showed tendencies at lower level before
Phineas Gage
- rod go through head and frontal lobe and eye
- personality changes in memory, exec fxn, inhibition, disruptions, heavy drinker, unemployable, fighter
what do damages to the frontal lobe cause?
agitation
irritability
short temper
failure to discontinue harmfulm maldaptove behavior
pbsessions
confusion
compromised insight
what does damage to the frontal lobe show similarity to?
elderly with dementia
are outbreaks of aggression attributable to TBI?
not common
11% for the first time
- unfocused aggression when it occurs
- no real underlying reasoning or planning
- acute phase of injury
- not clearly related to severity of injury
- secondary consequences to frustration
- tolerance of exogenous substance lowered
- more typical threats are uttered
what is the 80/20 rule?
80% of recovery happens within first year, 20% between year 1 and 2
- at end of 6M neuropsychologists can predict how much more recovery can occur
what is the most common site of injury?
frontal lobe
what are the 2 patterns that emerge?
lethargic, apathetic, indifferent
- impulsive and aggressive
what is the coup-countercoup injury?
- brain can move back and forth in jelly case
- damage in 2 opposite sides of brain
- initial then other end gets hit
Howard D
- was Dr.Freedmans transorbital lobotomy patient to reduce ADHD and neg emotions towards his dad getting with another girl
what is the purpose of limbic sys?
deep mid-brain strucutres (amygdala and hipp)
- emotional reg and memory consolidation
- damage in that area is highly emotional
- fear switches to anger
- high level of aggression in previously peaceful patients
- elaborate planning
temporal lobe epilepsy
fast spike-like activity in EEG over temporal lobe accompanied by increased risk for aggression
- followed by confusion and limited recall
NT and T
all are essential and non connected to level of aggression
- T in M + correlated with aggression
- NE and ATCH elevated in BPD type 1
