Lecture 2 - Love and prosocial behaviour 1 Flashcards
What is genetic variation in vasopressin receptor gene AVPR1A associated with?
Pair-bonding behaviour in humans
How did Bartels and Zeki (2003) use neuroimaging subtraction to find neural correlates of maternal and romantic love?
Neuroimaging subtraction technique:
Task activation pattern MINUS control pattern
Show person picture of another’s daughter or husband
This is control
Then show person picture of their daughter or husband
This is task activation
Can see which areas specifically are active due to maternal and romantic love
What did Bartels and Zeki (2003) find about neural correlates of maternal and romantic love?
Specific regions for each kind of love, as well as overlapping areas in the brain’s reward system that coincide with areas rich in oxytocin and vasopressin receptors
Is the prairie vole monogamous?
Yes
A male and female typically form a life-long pair bond after one mating/ cohabitation episode
Rare to be a monogamous mammal
What is the evolutionary reason behind biparental care in humans?
If you wanted to make a species evolve whose brain was so complicated and capable of such intelligence and adaptability that it takes an individual c.13 years to become fairly independent, and c.20 years to fully mature
Imagine the resources and time that would need to be devoted to the young of such a species!
Male and female team up as economic unit - makes sense as individual humans require lots of investing and resources
What does a monogamous social structure entail?
Lasting pair bond between adult mates
Both male and female care for offspring
What type of chemical are oxytocin and vasopressin?
Prosocial neuropeptides
Generally, are oxytocin and vasopressin more important in males or females?
Oxytocin more important in females ♀
Vasopressin more important in males ♂
What brain regions have higher oxytocin receptor density in the prairie vole compared to non-monogamous rat and mouse?
Nucelus accumbens, caudate, putamen
What is the method of staining for areas with more oxytocin/vasopressin receptors?
Inject radioactive substance that binds to vasopressin/oxytocin receptors
After animal killed and dissected, more of the substance indicates more receptors as more has bound
What brain regions have higher oxytocin receptor density in the prairie vole compared to non-monogamous montane vole?
PFC = prefrontal cortex
CP = caudate and putamen
NAcc = Nucleus Accumbens
How was the role of oxytocin investigated using blocking?
By blocking oxytocin receptor activity in the receiving neurons in oxytocin-receptor-rich brain regions
Inject something that binds to receptors but does not function as oxytocin
What was the method of the partner preference test by Ross and Young (2009)?
Cohabitation period - Bring together a male and female vole together for a fixed cohabitation period (c. 18-24 hours.) Observe. They may mate (check for mating.) Subject may be male or female. Partner and stranger = opposite sex.
Typically female in oxytocin studies, male in vasopressin studies
Test period - Then observe interactions over a test period (e.g. 3 hours)
Compare vole they cohabitated with and the new vole they did not know
Ask eg. How much time do these sexual partners spend side-by-side? Then compare to ‘stranger’ vole who has not mated with subject.
Observations should be scored blind to experimental group
What did Ross and Young (2009) find about oxytocin in their partner preference test?
Control - cerebrospinal fluid - unaffected (more time with partner than stranger)
Oxytocin antagonist - prevents oxytocin from bonding - in these areas:
Nucleus accumbens and PFC - affected (more time with stranger than partner) key areas for oxytocin influencing pair bonding
Caudate and putamen - part of basal ganglia - reward system - unaffected (more time with partner than stranger)
Key areas - nucelus accumbens or PFC
When do oxytocin and vasopressin peak in human males during sexual activity?
Vasopressin - during arousal
Oxytocin - during orgasm
What are the differential roles of oxytocin and vasopressin in human males?
Vasopressin - wanting? seeking?
Appetitive?
Like Dopaminergic
Signal in nucleus accumbens
Oxytocin - liking?
More towards ‘satisfaction’
More like Opioidergic signal
What does the opiod-antagonist naloxone do to females after sexual activity?
Blocks release of oxytocin after orgasm - less pair bonding
How do the two neuropeptides oxytocin and vasopressin interact with the reward system?
Produce attachment towards person with whom you feel nice/orgasm with
What was the result of manipulating the gene expression of V1aR gene in the solitary meadow vole? (Lim et al, 2004)
They showed much increased partner preference
How was the V1aR gene overexpressed in Lim et al (2004)?
Part of the gene in a prairie vole was inserted into the meadow vole brain (ventral pallidum) using a viral vector
What was the result of Lim et al (2004) changing gene expression of V1aR gene in meadow voles?
Meadow voles who are usually promiscuous showed significantly increased huddling with partner behaviour compared to control gene and same gene injected into different areas (i.e. not ventral pallidum)
What does overexpression of V1aR gene lead to? (Lim et al, 2004)
Increases number of Vasopressin 1A receptors (proteins) on the post-synaptic membranes of vasopressin-responsive neurons (in that brain region). The same amount of vasopressin released would now have a much larger effect on the vasopressin-responsive neurons.
What behaviour does increased V1aR receptor density result in?
Adult pair bonding (at least for males)
Cuddly monogamy
Does variation in receptor activity (oxytocin and vasopressin) control strength of pair bonding?
Neural manipulation experiments suggest yes:
Blocking these receptors eliminates post-coital huddling
Increased receptor density increases post-coital huddling
What is an issue with experiments examining species differences or experimentally-induced (exogenous) differences?
Does not examine individual differences in humans - cannot say the same thing happens in humans
Can oxytocin and vasopressin levels be studied using causal manipulations causing exogenous variation in humans?
No - this would be unethical
Instead, we can observe endogenous (naturally occurring) variation
Is this the same gene? V1aR gene, AVPR1A, vasopressin receptor 1A gene
Yes
What did Walum et al’s Partner Bonding scale comprise of questions from?
Consisting of 13 items overall:
Dyadic adjustment scale (DAS) (7 items)
(getting along, doing things together)
Support Seeking and Giving (SSG) assessment (5 items)
(positive social engagement)
Marital instability scale (MIS) (1 item)
(Serious Marital Threat question
Has subject experienced marital crisis or threat of divorce during the last year? From a Life Events questionnaire)
Also - marital status - married or cohabiting?
What is a limitation of the sample used in Walum’s study of AVPR1 and marriage satisfaction?
All couples were together for 5 years - does not include people whose expression of the gene makes them not want to be in a long-term relationship at all
However, this may explain small effect sizes - the present study may underestimate the way in which the 334 allele predisposes against ‘marriage’
What were the conditions for men’s genetics in Wallum’s study of AVPR1?
0 copies of risk allele, 1 copy or two copies
Allele - more likely to have worse marriage
What were results of Walum’s study of AVPR1 and marriage satisfaction?
If you are a male ♂ with one or two copies of the risk allele:
You are less likely to get married
(an objective fact)
You are more likely to experience a serious threat to your relationship
(your self-report)
You show a less-bonded pattern of relationship with your partner
(your self-report)
Your female partner reports less quality in the relationship
Particularly regarding affection
Finally, no significant effects for female polymorphisms of the AVPR1a gene
Shows vasopressin more relevant for males than females
How did positive and negative conflict behaviour vary in men and women when resolving an artificial conflict after being given intra-nasal oxytocin spray? Ditzen et al (2009)
Oxytocin - more positive behaviour
Placebo - more negative behaviour
Men show higher pos and neg levels - women do not vary as much
Does oxytocin reduce stress?
Yes
Subjects given oxytocin show lower cortisol levels after couple conflict
Shows exogenous variation
How did Gonzanga et al (2006) test for romantic display associated with oxytocin release?
25 young women recount and relive a positive emotion regarding love or infatuation with their male partners present (typically 2 minutes long)
Blood drawn from subjects during this and earlier baseline condition, later tested for oxytocin content
Scorers observe non-verbal behaviour in women:
Affiliative (romantic), e.g. affirmative head nods, Duchenne smiles (genuine smile), leaning towards partner
Sexual, e.g. lip licking, lip puckering, tongue protrusions
Does romantic display correlate positively with oxytocin release? (Gonzanga et al., 2006)
Yes
Duration of romantic displays as % of duration of romantic episode narration… (~ 2 minutes) correlated positively with increase in oxytocin relative to first baseline
Does oxytocin correlate with overt sexual displays? (Gonzanga et al., 2006)
No correlation of oxytocin with overt sexual displays
Maybe not appropriate index of sexual behaviour
What is the strategy mediated by oxytocin and vasopressin compared to that of testosterone?
Strategy mediated by Oxytocin & Vasopressin
‘Quality of bond not quantity’
Commitment to existing bonds
i.e. enhancement of adult pair bond
i.e. enhancement of parenting
Reduced aggression with mate & progeny
- Co-operative - brings benefits of monogamy - promotes love
Strategy mediated by Testosterone
‘Quantity of mates not quality’
Focus upon more partners
More attractive partner?
i.e. more ‘mating’, less ‘pair bonding’
i.e. more children
Higher aggression with mate & progeny?
- Competitive - brings benefits of polygamy (infidelity) - promotes sex
Why are there two strategies for reproduction? - quantity and quality (mediated by different chemicals)
Pure strategy of either not that evolutionarily stable?
- If everyone is ‘high TEST’ only, children die at too high rates, or do not thrive, from abandonment & low parental investment. Influx of ‘high OXT/VASP’ will spread because children suddenly thrive to adulthood, and then produce children themselves.
- If everyone is ‘high OXT/VASP’ only, network is highly vulnerable to influx of ‘high TEST’ strategy. A bit like loafers.
So humans exhibit a mixture of both strategies, and individual differences.
What happens to testosterone during ageing?
It reduces
Are men producing more testosterone less likely to marry? (Booth and Dabbs)
Yes, and more likely to divorce
Are men with higher testosterone more likely to leave home because of troubled marital relations, have extramarital sex, physically abuse spouse and have lower quality of marital interaction?
Yes
What is a strength of (Booth and Dabbs)? (Testosterone and marriage)
Adjustment for age
Many different facets of this form of adult pair bonding (marriage)
What is the likelihood of hi-test compared to low-test men to not get married, to divorce/seperate, to be unfaithful and to be abusive
Hi-test men > doubly likely to not get married
Hi-test men > nearly doubly likely to divorce/separate
Hi-test men > nearly doubly likely to be unfaithful
Effect not as clear for abusive behaviour - other factors at play
According to Mascaro, Hackett and Rilling (and others), the biology of human males represents a trade-off between what two things?
a) effort spent on mating
&
b) effort spent on parenting
Chin et al studied homosexual women couples’ testosterone levels, pair bonding and parenting - what did results indicate?
These Negative correlations were reported:
1) Birth mothers reported HIGHER relationship satisfaction when their partners had LOWER testosterone (TEST)
2) Non-birth mothers reported higher perceived support and relationship commitment when their partners had LOWER TEST
3) Non-birth mothers with LOWER TEST reported receiving MORE support, and HIGHER relationship satisfaction, commitment & investment
Are testosterone level heritable?
Yes
What are the testosterone level correlations between dutch adolescent twins?
Correlations in MZ > correlations in DZ twins
Identical twin values (MZ) are very similar (in both males & females) and higher than for non-identical twins:
males: 0.66 > 0.34
females: 0.60 > -0.01
What is the relationship between fatherhood and marriage, and testosterone?
Seems likely that the experience of marriage and fatherhood lower testosterone,
as well as that low testosterone predisposes to less marriage and fatherhood
What effect does child maltreatment have on adult oxytocin levels?
Maltreatment = drop in oxytocin
What is a reason for lower oxytocin levels in adults who have experienced child maltreatment?
1) Low-loving interactions (hugs/cuddles/praise) gradually reduce OXT
2) Protective mechanism – ‘shutting down’ normal levels of prosocial responsiveness because these would lead to more stress/pain (avoid getting hurt)
What do the GG/GA alleles of the rs53576 SNP of the Oxytocin Receptor typically confer?
Increased empathy and trust
What effect does child maltreatment have on depression? (costs of being prosocial in a low-loving adverse world)
Depends on allele of oxytocin receptor?
Under high levels of childhood maltreatment, this prosocial predisposition becomes maladaptive.
Overly loving, trusting, giving to e.g. callous, psychopathic parents is not good for you.
- Prosocial individuals more likely to get depression
