Biological Substrates of Personality Central nervous system structure and function Frontotemporal...
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Transcript of Biological Substrates of Personality Central nervous system structure and function Frontotemporal...
Biological Substrates of Personality
Central nervous system structure and function
Frontotemporal lobar degeneration Personality change (more apathetic, less social, more emotionally blunted)
Eysenck Returns: Extraversion
Ascending reticular activation system: regulates arousal, wakefulness
Baseline arousal + environmental arousal = total arousal
Central nervous system structure and function
Eysenck Returns: Extraversion
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Introvert Extravert
Brain Environment
Ascending reticular activation system: regulates arousal, wakefulness
Baseline arousal + environmental arousal = total arousal
Biological Substrates of Personality
Autonomic nervous system
Sympathetic and parasympathetic branches
Eysenck Returns: Extraversion
Ascending reticular activation system: regulates arousal, wakefulness
Baseline arousal + environmental arousal = total arousal
Baseline arousal determines environmental choices to regulate total arousal
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Introvert noise choice Extravert noise choice
Introverts Extraverts
(From Geen, 1984)
Central nervous system structure and function
Limbic system (hippocampus, amygdala, septum, prefrontal cortex, and others) is the seat of the emotions
Eysenck Returns: Neuroticism
BIS and BAS
Behavioral approach system (BAS) is thought to be mediated by the basal ganglia, which can disinhibit other structures
Reward-seeking
Behavioral inhibition system (BIS) is thought to be mediated by the frontal cortex and limbic system
Punishment-avoiding
Central nervous system structure and function
BIS and BAS
Behavioral approach system (BAS) is also associated with greater left than right hemispheric activation in the frontal lobes
Reward-seeking
Behavioral inhibition system (BIS) is, conversely, associated with greater right than left hemispheric activation
Punishment-avoiding
Central nervous system structure and function
Biological Substrates of Personality
Transmitter systems
Major brain transmitters: serotonin (5HT), norepinephrine (NE), dopamine (DO). Systems are affected by production, reception, and potentiation.
Transmitter systems
Can drugs that affect neurotransmitters affect personality?
Selective serotonin reuptake inhibitors
Examples: Prozac (fluoxetine, 1988); Serzone (1990), Celexa (1991), Paxil (1992), Zoloft (1993), Luvox (1994), Remeron (2001), and so on
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Number of US prescriptions per year
Transmitter systems
Listening to Prozac (Kramer, 1997)
“I believe Tess’s story contains an unchronicled reason for Prozac’s enormous popularity: its ability to alter personality. Here was a patient whose usual method of functioning changed dramatically. She became socially capable, no longer a wallflower but a social butterfly. Where once she had focused on obligations to others, now she was vivacious and fun-loving. Before, she had pined after men; now she dated them, enjoyed them, weighed their faults and virtues. Newly confident, Tess had no need to romanticize or indulge men’s shortcomings.”
Tess: eldest of 10 children from impoverished, abusive background; history of maternal depression; married at 17 to abusive, alcoholic husband and later divorced; multiple symptoms of major depressive disorder; treated with Prozac for 2 weeks
Transmitter systems
Listening to Prozac (Kramer, 1997)
Tess: eldest of 10 children from impoverished, abusive background; history of maternal depression; married at 17 to abusive, alcoholic husband and later divorced; multiple symptoms of major depressive disorder; treated with Prozac for 2 weeks
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Depression improvement
Natural history
Placebo
Prozac
Transmitter systems
“Selective Alteration of Personality and Social Behavior by Serotonergic Intervention” (Knutson et al., 1998, American Journal of Psychiatry)
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Affiliation Negative affect Positive affect Hostility
SSRI Placebo
Affiliation: suggestions vs. commands, grasps in a cooperative puzzle task
Temperament
Defining characteristics in common with a general definition of personality:
individual differencestable
Defining characteristics specific to temperament:
partially heritableneurophysiological underpinningspresent during early life
Temperament
Inhibited temperament (Jerome Kagan)
Defining characteristics in common with a general definition of personality:
individual difference: inhibited children (15-20%) are shy, timid, fearful, restrained; uninhibited children (20-25%) are bold, spontaneous, fearlessstable: infant tests predict play styles in childhood
Defining characteristics specific to temperament:
partially heritable: boys MZ r = .64, DZ r = .25girls MZ r = .45, DZ r = .22
neurophysiological underpinnings: SNS arousabilitypresent during early life: evident as early as 4 months of age
Temperament
Other kinds of temperament (Buss and Plomin, others)
activity: energy, physical movement, squirming
positive emotionality/sociability: enjoy interactions with others
negative emotionality: easily upset, fussing, crying
impulsivity/distractability: less careful and thoughtful, easily distractable
approach-withdrawal: similar to BIS/BAS
Sex differences: Personality of 313
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O C E A N
Men Women
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AgreeableEmpatheticTrustingExtravertedAnxious
Men:AggressiveAssertive
No difference:ImpulsiveOrderlyOpenReflective
5ARD (5-alpha-reductase deficiency)
Converts T to DHT – DTH is necessary for development of male external genitalia. Virilisation may occur at puberty.
“Huevo a los doces” (Dominican Republic)
Autosomal recessive inheritance
Sex differences: Hormonal systems
Children: congenital adrenal hyperplasia and prenatal exposure to androgens
Men: correlations between T and crime, education, profession, and marriage
Women: study of 87 maximum-security inmates (aged 17-60)
T 1 2 3
1. age -.43
2. criminal violence .18 .05(theft vs. self-defense vs. homicide, assault)
3. aggressive dominance .34 -.25 -.25(trouble, aggression, domination, violations)
Sex differences: Evolution and mating strategies
Issue Females Males
Reproductive constraints A limited number of children No constraints on reproduction
Optimal strategy Best quality mate Largest number of mates
Desired mate quality Resources, fidelity Childbearing capacity, promiscuity
Indications of quality Earning capacity, status, Physical attractiveness, health,possessions, generosity, youthambition
Most likely basis for jealousy Sexual infidelity with other Emotional attachment to otherby partner (certainty of paternity) (certainty of resources)