Transcript 38_Personality

Announcements
Final 8:00, Friday, May 11.
(A-L here; M-Z 100 MSEB)
Predictions:
females
males
Women prefer less masculine male faces (and men prefer more
masculine faces in women) for long term relationships under
conditions of environmental harshness.
Consistent with idea that high-quality partners may be low
investors and suggests that under harsh ecological conditions, men
and women prefer a low quality / high investment partner for long
term relationships.
Behavior and relatedness
Like many animals, social groups in humans are often made up of
related individuals.
Behavior and relatedness
Behavioral Syndromes
correlation of behavior across multiple contexts
for example, aggression (territorial disputes vs. mating)
Same as personality in humans?
The nature of personality
Growing consensus that many descriptors of personality can
be characterized into five broad underlying dimensions of
personality (The Big Five Model – John, 1990)
High score
Extraversion
Tendency to be engaged
assertive, energetic,
sociable
Neuroticism
anxious, emotional,
Tendency toward neg.moods moody
Conscientiousness
Tendency to plan & conform
Agreeableness
Tend to cooperate
Openness
Tend toward diversity
dependable, organized,
practical
cooperative, generous,
warm
curious, imaginative,
insightful
Low score
quiet, shy, withdrawn
calm, at ease, unemotional
careless, irresponsible
frivolous
cold, quarrelsome, selfish
shallow, simple
The nature of personality
High score
Low score
Extraversion
extroverted
introverted
Neuroticism
nervous, high-strung
calm, relaxed
Conscientiousness
conscientious
disorganized
Agreeableness
agreeable
disagreeable
Openness
open to new experiences
close-minded
Take the Big Five test:
http://www.outofservice.com/bigfive/
The nature of personality
•
Assessment of individual differences on these 5 dimensions
can be determined reliably by self-report
•
Personality is predictive of a wide range of social and
work-related behavior and some behavioral pathology,
personality can be an independent risk factor for mental health
problems
– Individuals who are impulsive and disinhibited in childhood
have elevated risk of alcoholism and other substance abuse
disorders in adulthood
– Caspi et al 1996
– Clinical depression hypothesized to be due to high levels of
neuroticism coupled with low levels of extraversion – Watson
et al 1994
Twin Studies on Personality
• Additive genetic factors account for 40-60% of the
variance in personality
• Shared environmental influences are negligible
• Non-shared environmental effects account for
50% of the variance
-different experiences in the same environment-differential
parental treatment of siblings or favoritism
-different experiences in different environments --having
different friends in school
-reacting to the same event in different ways-parental
divorce
Adoption Studies on Personality
•
Consistently find little/no personality similarity among adoptive
relatives
•
Loehlin (1992) – compute weighted-average correlation between
nonbiologically related siblings reared together
– Extraversion (3 studies, n=258)
-0.07
– Neuroticism (3 studies, n=258)
0.11
– Agreeableness (2 studies, n=250)
0.06
– Conscientiousness (2 studies, n=245)
0.02
– Openness (2 studies, n=241)
0.06
Genes involved with personality
1.
2.
3.
4.
5.
DRD4
Serotonin transporter gene, 5HTT
Monoamine Oxidase
Nitric oxide synthase
Fos B
Cell. 1996 Jul 26;86(2):297-309.
A defect in nurturing in mice
lacking the immediate early
gene fosB.
Brown JR, Ye H, Bronson RT, Dikkes P, Greenberg ME.
The Fos family of transcription factors
 are induced by environmental stimuli that trigger adaptive neuronal
response.
 fosB mutant mice are profoundly deficient in their ability to nurture
young animals but are normal with respect to other cognitive and
sensory functions.
 The nurturing defect is likely due to the absence of FosB in the
preoptic area, a region of the hypothalamus critical for nurturing.
 These observations suggest that a transcription factor controls a
complex behavior by regulating a specific neuronal circuit
- indicates nurturing in mammals has a genetic component.
Association of dopamine D4 receptor (DRD4)
with novelty seeking
– Neurotransmitter dopamine has been implicated in
brain reward and approach systems
– Novely seeking does not align precisely with any
one of the big 5 personality factors but is associated
with high levels of extraversion and low levels of
conscientiousness
•
Impulsive, exploratory and
extravagant
Elovainio, et al. 2005. The mediating role of novelty seeking in
the association between the type 4-dopamine receptor gene
polymorphism and cigarette-smoking behavior.
Examined the relationship between variation at type 4 dopamine
receptor gene and cigarette-smoking behavior and the mediating
role of the temperamental novelty seeking.
The two- and five-repeat alleles were significantly more common
in the group of current smokers than others (ratio 2.53). After
controlling for the effect of novelty seeking on smoking behavior,
the relationship dropped substantially, being no longer
statistically significant.
Neuroticism and the serotonin transporter gene
http://www.driesen.com/ssrireuptake.jpg
Serotonin is 5-HT (5-hydroxytryptamine), serotonin transporter is 5-HTT
5-HT is serotonin
5-HTT--serontonin transporter (presynaptic side)
5-HTT is also the target of cocaine and methylphenidate
5-HT receptors are stimulated by LSD
Association of the serotonin transporter with
disease
Polymorphisms in 5-HTT in the promoter region
16-repeat- l long
14-repeat-s short
‘s’ is associated with reduced transcription and is
dominant to ‘l’
Individuals with at least one copy of ‘s’ scored higher on
Neuroticism
Association with 5-HTT has been reported for violent suicide
and early onset alcoholism
Dopamine plays a role in novelty-seeking behavior
Serotonin is important for neuroticism
Studies in knock-out mice
Null mutants for the serotonin 1a receptor
(5-HT1A) show elevated levels of anxiety
Null mutants for 5-HT1B show reductions in anxiety
and elevations in aggression
mutation in a single Dutch family correlates with violent behavior
Null mutants for DRD4 show reduced response to novelty
 The interaction between low serotonin and high testosterone levels in
the central nervous system has a significant effect on the neural
mechanisms involved in the expression of aggressive behavior.
 Testosterone modulates serotonergic receptor activity in a way that
directly affects aggression, fear and anxiety.
Schizophrenia
•
A chronic, severe and disabling brain disease
•
Characterized by profound disturbances of cognition, emotion,
and social functioning
•
1% of the population develops Schizophrenia during their
lifetime
•
Affects men and women equally – men in late teens and early
20s; women in 20s and 30s
•
Central features include both “positive” (additional behaviors)
and “negative” (loss of normal behaviors) symptoms
Schizophrenia
Some people have only one psychotic episode
during their lifetime
Others have many episodes during a lifetime but
lead relatively normal lives during the interim
Individuals with chronic or recurring
schizophrenia often do not fully recover
There is no definitive marker: diagnosis is made
on self-reporting
Schizophrenia - symptoms
– hallucinations
– delusions
– disorganization of thoughts
– bizarre behavior
– incongruity of affect (improper behavior
relative to the specific situation
Schizophrenia - symptoms
Males have an earlier age of onset than females
male incidence peaks in mid-20s
female incidence peaks around 30
second, lower incident peak around menopause
Schizophrenia – evidence for a genetic influence
• runs in families
• 40-50% risk for
monozygotic twins
• 10% risk to child of
affected parent
Schizophrenia – evidence for a genetic influence
Evidence suggests that the
predisposition is inherited, not
the certainty of developing
Schizophrenia itself.
Genetic models for Schizophrenia
•
Based on family studies, current models support
existence of two or three susceptibility loci
•
liability alleles confer ~ two-fold increase in risk to
the sibling of an affected individual
•
Linkage studies support this model – identification of
several weakly-linked regions of the genome
Environmental Factors
• Schizophrenics are more likely to be born in
winter or early spring
Why?
some seasonally varying factor alters the
developing CNS, increasing an individual’s
lifetime risk
parents of schizophrenic patients have an unusual
pattern of conception
One of the most consistent findings in schizophrenia is that the distribution of birth dates of
individuals with schizophrenia differs from that of the general population.
Are there genes for behaviors?
“anxiety and aggression” gene?
http://www.sciencedaily.com/releases/2003/01/030123072840.htm
“alocholism” gene?
Gene Linked To Alcoholism Alcoholism tends to run in families,
suggesting that addiction, at least in part, has an underlying
genetic cause. Now, researchers at the University of Illinois at
Chicago have discovered a gene linked to alcohol dependency.
Laboratory mice deficient in the gene were found to consume
excessive amounts of alcohol, preferring ethanol to water and
evincing highly anxious behavior in a maze test.
Drunken Fruit Flies Reveal Molecular Pathway Regulating
Sensitivity To Alcohol (June 17, 1998) -- Researchers at UC
San Francisco have identified a molecular pathway in intoxicated
fruit flies that is responsible for regulating the flies' meandering,
wobbling responses to alcohol.
http://www.sciencedaily.com/releases/2004/05/040526063645.htm
Variation in a gene called
VMAT-vesicular monoamine
transporter 2
C-correlates with selftranscendence, which
correlates with spirituality
A-does not
Reported in a book by
Dr. Dean Hamer, The God
Gene: How faith is hardwired
Into our genes
Chief of gene structure, NCI