Biological Substrates of Personality

1. Biological Substrates of Personality Central nervous system structure and function Frontotemporal lobar degeneration  Personality change (more apathetic, less social, more emotionally blunted)

2. Eysenck Returns: Extraversion Central nervous system structure and function Ascending reticular activation system: regulates arousal, wakefulness Baseline arousal + environmental arousal = total arousal

3. Eysenck Returns: Extraversion Ascending reticular activation system: regulates arousal, wakefulness Baseline arousal + environmental arousal = total arousal

4. Biological Substrates of Personality Autonomic nervous system Sympathetic and parasympathetic branches

5. 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 (From Geen, 1984)

6. Eysenck Returns: Neuroticism Central nervous system structure and function Limbic system (hippocampus, amygdala, septum, prefrontal cortex, and others) is the seat of the emotions

7. BIS and BAS Central nervous system structure and function 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

8. BIS and BAS Central nervous system structure and function 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

9. Biological Substrates of Personality Transmitter systems Major brain transmitters: serotonin (5HT), norepinephrine (NE), dopamine (DO). Systems are affected by production, reception, and potentiation.

10. 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 Number of US prescriptions per year

11. 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 “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.”

12. 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

13. Transmitter systems “Selective Alteration of Personality and Social Behavior by Serotonergic Intervention” (Knutson et al., 1998, American Journal of Psychiatry) Affiliation: suggestions vs. commands, grasps in a cooperative puzzle task

14. Temperament Defining characteristics in common with a general definition of personality: individual difference stable Defining characteristics specific to temperament: partially heritable neurophysiological underpinnings present during early life

15. 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, fearless stable: infant tests predict play styles in childhood Defining characteristics specific to temperament: partially heritable: boys MZ r = .64, DZ r = .25 girls MZ r = .45, DZ r = .22 neurophysiological underpinnings: SNS arousability present during early life: evident as early as 4 months of age

16. 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

17. Sex differences: Personality of 313 Women: Agreeable Empathetic Trusting Extraverted Anxious Men: Aggressive Assertive No difference: Impulsive Orderly Open Reflective * * *

20. Sex differences: Hormonal systems testes ovaries adrenal gland

21. 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

22. 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)

23. 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, youth ambition Most likely basis for jealousy Sexual infidelity with other Emotional attachment to other by partner (certainty of paternity) (certainty of resources)

24. Sex differences: Evolution and mating strategies