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Hormones & Behavior > Chapter 8: Social behavior 
 > Flashcards

Chapter 8: Social behavior 
 Flashcards

1
Q

What is social behavior?

A

Encompasses interactions between individuals from which one or more of the individuals benefit

Aggressive behavior
Affiliation
Courtship
Parental behaviors

Affiliation: social behaviors that bring animals together

Territorial/Aggression: social behaviors that keep animals apart

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2
Q

Affiliation

A

social behaviors that bring animals together

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3
Q

Territorial/Aggression

A

social behaviors that keep animals apart

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4
Q

Origins of Prosocial Behaviors

A

Mcdougall hypothesized that prosociality was a natural consequence of parental instincts, the result of “tender emotions” originally directed towards offspring that were later co-opted to promote the helping of others.

Oxytocin would seem a likely substrate for these tender emotions.

Oxytocin increases activation in reward system and empathy system.

Hormones (like Oxytocin) associated with regulation of parental behavior may have co-opted over evolutionary time to serve as modulators of prosocial behaviors.

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5
Q

Vampire bat

A

shares meal with offspring and may also share with unrelated animals

Relies on social recognition, social memory, strong social bonds, and reciprocity

Social behavior as an ‘offshoot’ of parental behavior

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6
Q

Social vs. solitary behaviors:


species and seasonal differences

A

Breeding season predicts social behavior in female meadow voles

Territorial aggression vs. affiliation

During winter months, females prefer contact with other females to males; do not have to compete for males

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7
Q

Costs of group living

A

Increased ease of disease transmission

Increased competition for food, mates, and nesting sites

Increased susceptibility to predators

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8
Q

Benefits of group living

A

Group defense of resources

Elevated foraging efficiency

Anti-predator detection and defense

Increased mating opportunities

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9
Q

Social Affiliation Behavior

A

Thought to have evolved from parental and reproductive behaviors

In many instances, hormones that mediate reproductive and parental behaviors, mediate affiliation as well.

Hormonal systems for social behavior highly conserved.

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10
Q

Nonapeptides

A

An oligopeptide containing 9 amino acyl residues

Examples: oxytocin, vasopressin

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11
Q

Overlap between romantic and maternal love activation patterns in brain?

A

Compared the neural circuitry underlying both types of love

Adults shown pictures of loved ones and pictures of people they know while in fMRI scanner.

Mothers were shown pictures of their babies or other infants.

Found overlapping areas of brain activation including the Basal Ganglia, as well as the Medial Insular and Anterior Cingulate Cortex.

Emphasizes that affiliative behaviors likely evolved from parental behaviors.

Brain regions with the most activation either are part of the brain’s reward circuitry (mesolimbic DA—ventral tegmental area, nucleus accumbens) or contain a high density of oxytocin & vasopressin receptors.

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12
Q

the brain’s reward circuitry

A

mesolimbic DA
ventral tegmental area
nucleus accumbens

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13
Q

Social bonding:

Partner preference

A

Prairie voles form partner preferences and long-term bonds

Social preferences can be determined in the 3-chamber preference apparatus

Partner preference is stable

Social bonding and partner preference not the same as sexual monogamy

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14
Q

Hormones underlying social affiliation:


Oxytocin (OT)

A

Using autoradiography the oxytocin receptor of monogamous and polygamous voles have been characterized.

Species difference also true for vasopressin V1aR too

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15
Q

Prairie Voles

A

Monogamous

Long-Lasting Pair Bonds

Pair bond doesn’t form if OT receptor blocked.

Lower circulating testosterone concentrations

Lower sperm numbers

Smaller testes

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16
Q

Meadow and Montane Voles

A

Polygamous

Higher circulating testosterone concentrations

Higher sperm numbers

Larger testes

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17
Q

Hormones underlying social affiliation:


Testosterone

A

Correlations between blood T concentrations and testis size, sperm counts, and social affiliation
(monogamy vs polygamy)

Lower T could indirectly mediate approach behaviors needed to care for offspring.
Hormones that evoke affiliation thus serve as a means of bringing about this cooperation.

Supplemental T to a monogamous vole will not induce promiscuity, just as castration of a polygamous vole will not induce monogamy.

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18
Q

_____ is more important in pair bond formation in females

A

Endogenous Oxytocin is more important in pair bond formation in females

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19
Q

_____ is more important for males

A

Endogenous AVP is more important for males

Oxytocin has role too

Yet distribution of receptors is same in males and females

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20
Q

Pair bond formation is rewarding

A

PreFrontal Cortex, Nucleus Accumbens (NA), VP —> reward and pair bond circuitry

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21
Q

Other hormones and factors that influence partner preference

A

Endogenous OT is more important in pair bond formation in females

Endogenous AVP is more important for males, though OT has role too
Yet distribution of receptors is same in males and females

PFC, NA, VP- reward and pair bond circuitry

Pair bond formation is rewarding
Opiod system.
Endogenous opiod antagonism prevents partner preference

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22
Q

Pair bond leads to increase in Dopamine and dopamine receptors in Nucleus Accumbens

A

Mating in prairie voles increases Dopamine turnover in reward system

Pair bonding also increases Dopamine receptor D1

Dopamine acting on D2 receptors in Nucleus accumbens leads to formation of pair bond following sexual encounter with new partner

Pair bond formation is rewarding

23
Q

D1

A

Pair bonding increases Dopamine receptor D1

D1 receptor has no effect on initial formation, but a role in maintenance of social bond

D1 receptors mediate aggression toward stranger to solidify pair bond with partner

After bonded, D1 receptor increases linked to aggression towards stranger females.
Bonded males will prefer partner and attack stranger female. D1 antagonist blocks attacking stranger, D2 has no effect.

Meadow voles (the polygamous ones) have higher D1 receptor expression than prairie voles.
Antagonizing D1 in meadow voles also increases time spent with females.
24
Q

D2

A

Dopamine acting on D2 receptors in Nucleus Accumbens leads to formation of pair bond following sexual encounter with new partner

No affect on aggression

Involved in making a meadow vole monogamous.

25
Q

Making a meadow vole monogamous?

A

Overexpress V1aR receptor in nucleus accumbens (ventral pallidum) of meadow voles

Partner preference can be induced

Also D2 dependent

26
Q

Oxytocin and social monogamy in humans:

A

Heterosexual men self-described as “passionately in love”

Effect of oxytocin on reward system activation (fMRI) while viewing pictures of partner or attractiveness and feature matched stranger

Both ventral tegmental area (VTA) and nucleus accumbens (NA) show greater activation to partner than unfamiliar if OXY given 1st

27
Q

Oxytocin Modulates Social Distance Between Males and Females

A

Participant asked to choose ideal distance to stand from an attractive female experimenter (in some, had to advance (far), in others had to retreat (close)

Oxytocin increased ‘ideal’ distance between male participant and female experimenter in men in a relationship

Single men showed no effect of oxytocin to increase social distance

No effects of oxytocin when experimenter was male (heterosexual subjects)

28
Q

Oxytocin and autism

A

Oxytocin receptor polymorphisms seen in some autistic individuals, no difference in oxytocin levels overall.

Intranasal oxytocin can increase ‘empathy’ related brain activation, eye contact, and perception of social cues in high functioning autistic individuals

Oxytocin increases salience of social cues

Still unclear if intranasal oxytocin gets into brain

Clinical trials underway; concern about chronic treatment during development

29
Q

Human-dog affiliative behavior and Oxytocin

A

Measure dog-owner interactions

Dogs that gaze more at their owners show higher Oxytocin following a 30min interaction, as do their owners

Not so in hand-raised wolves, where eye contact is aggressive or threatening to prey

30
Q

Aggression

A

Social behavior that keeps animals apart

Overt behavior with intention of inflicting damage or unpleasantness on another

Superficially, the opposite of affiliation

Mediated by partially distinct circuits rather than differential activity of the same neurons

31
Q

Types of aggression

A

Conflicts over limited resources such as territories, food, and mates arise

Each type has a different physiological cause and is expressed in different environmental and social context

A social interaction decides which animal gains access to the resource.
Gains can be substantial, but costs as well, even for ‘winner’…

Maternal, inter-male, territorial, sex-related, rank-related are all mediated by hormones

Some are evoked in the lab: irritable aggression (restraint), fear-induced (shock), resident-intruder tests

32
Q

Costs of aggression

A

Tradeoff between time & resources spent on aggression/winning, and time & resources spent on foraging, hunting, immune function etc.

33
Q

Hormones, season and aggression:

Red deer

A

Red Deer- live peacefully most of the time, in late summer antlers come into “hard horn”

Move to grassy areas and fight for control of the areas in early fall

Fierce battles, inflict damage

Social rank is based on ability to win the battles and oldest males are most experience fighters

After rutting season, shed antlers, aggression is reduced, go back to their bachelor groups

34
Q

Seasonal changes in aggression

A

At the end of the summer, T levels increase and peak in mid autumn, the rising androgen levels are accompanied by antler growth, and aggressive behavior.

Mating occurs for about 2 weeks in mid autumn.

After mating, Testosterone levels diminish, aggressive behaviors wane, and males engage in few agonistic interactions.

35
Q

Hormones and aggression in Red deer

A

New, soft antlers develop in High Testosterone levels destroy the velvet and it sheds at the end of summer

Low levels of Testosterone in winter cause stags to cast their antlers

Castration mimics reduction in testosterone and cause males to shed their antlers prematurely and thus plummet in rank

What happens if implanted with slow release testosterone capsules either in winter or summer?
Winter:
retained antlers due to constant supply of Testosterone, more aggressive, climbed in social rank
Summer:
climb in social rank even before antler development, aggressive before “weapon”

Mating still occurred during the appropriate autumn breeding season, suggesting that the estrous females generate a cue that stimulates the mating behavior.
Steroid hormones act on the brain to promote aggressiveness and act on the antler- the effectors of aggressive behavior

36
Q

Aggression in rodents

A

Territorial during breeding season, social & interactive during winter

At the end of breeding season undergo reproductive regression due to lower concentrations of androgens

Breeding season: control resources, promote survival of themselves & offspring, defend resources

Winter: group living, conserve energy, enhance survival. Reduction in aggression allows this.

37
Q

Some male rodents don’t undergo reproductive regression.

Advantages? Disadvantages?

A

They maintain testicular function and produce sperm & androgens during winter conditions.

High behavioral and energetic costs.

Capable of continuous breeding
Superior in fitness

May remain too aggressive during the winter to benefit from communal huddling

Give up energy savings

38
Q

In many species, inter-male aggression rises during the breeding season that parallels the rise in Testosterone.

A

Activational —>
castration reduces, T replacement reinstates

Too much or too little testosterone has fitness costs

39
Q

Seasonal changes in aggression in primates

A

Inter-male aggression during breeding season (i.e. lemurs & monkeys)

Human males:
Peak incidences of crime in North America are associated with high temperatures and peak androgen concentrations

Increased aggression for prisoners in a Maryland prison during the summer

Increased abuse reported by women in the U.S. during summer

40
Q

Puberty

A

Testes grow larger

Increased amounts of androgens are secreted into the circulatory system

Increased reports of aggression- specifically inter-male and isolation-induced aggression are first observed at this time

Aggression often peaks at puberty, often actually decline into adulthood

41
Q

Is it adaptive to have increased aggression during puberty?

A

Males of many rodent species disperse during this time, putting them in dangerous situations (encroaching on other males’ territories, competing for food, mates, etc.)

They have evolved to be aggressive to increase their odds of survival

Aggression often peaks at puberty and declines once adulthood reached

42
Q

Aggression in primates

A

Dispersal also occurs in primates during puberty, and young male rhesus monkeys become the target of adult aggressive behaviors, and must find a new group to join

Either burst into a new group, or hang in the periphery until the right time and sneak in!

Bursting into a new group could come with resistance and aggression towards the newcomer, but sneaking in also has disadvantages- could starve or succumb to illness.

43
Q

What strategy to choose?

A

Sons of a high ranking females tend to be outgoing, venture far from mother, low autonomic reactivity, low cortisol concentrations.
They tend to burst in.

Son of a low ranking female have high autonomic activity, high cortisol levels (experience more stress).

Early life stress exposure can decide these things for emergent adults.

44
Q

Sex differences in aggression

A

Overall, males are more aggressive than females

Sex differences appear at a very early age

Why are there differences?
Males have higher concentrations of circulating androgens
Males are exposed to androgens prenatally, wiring of brain therefore facilitates aggression
Boys are encouraged, girls discouraged

45
Q

Male mice castrated before PD6 treated with Testosterone during adulthood

A

Low levels of Aggression

ORGANIZATIONAL!!!

46
Q

Females ovariectomized before PD6 treated with Androgens in adulthood

A

Little to no Aggression

47
Q

Gonadectomized male or female treated with Testosterone perinatally prior to PD6, AND in adulthood

A

Typical levels of aggression seen in normal males

48
Q

IS the sex difference in aggression due to higher adult blood concentrations of androgens in males than in females, or are males more aggressive than females because their brains are organized differently by perinatal hormones?

So what does these result mean?

A

Aggression is organized perinatally by androgens but also requires the presence of androgens after puberty in order to be fully expressed.

Proclivity to act more aggressive (in males) is organized perinatally by androgens but also requires the presence of androgens after puberty in order to be fully expressed

49
Q

Experience with social behaviors influence hormones:

Winning

A

Behavior can feed back and affect hormone concentrations

Social defeat in many species is correlated with a reduction in levels of circulating androgens for many days after!!

Winning increases circulating androgens in males for the following 24h

True in humans too....
Home vs away:
higher T before home games
Challenging team:
if hard opponent, higher Testosterone before game, esp. in goalies

Just before a home game, testosterone levels in soccer players are higher than in away games.
Testosterone levels are also higher before playing against a challenging team than a moderate one.

Fans:
2002- osu beats michigan and had a perfect season —> riots started, couches burned

50
Q

Winning:

California mice

A

Winning a fight increases the male mice subsequent motivation to fight and enhances the ability to win- only if the previous winning experience was in his home cage

51
Q

winning on one’s own turf potentiates further aggression.

A

Winning in a place that’s familiar/important to you must be a factor.

52
Q

Winner Effect

A

mediated by androgens and associated with an up-regulation of androgen receptors in brain areas involved in reward, ventral tegmental area (VTA) and nucleus accumbens (NA).

53
Q

Giving testosterone is more effective at increasing aggression in subsequent conflicts if paired with a winning conflict (testosterone following win)

A

…

54
Q

Conditioned Social Defeat

CSD

A

Refers to losing a confrontation

Defeat of Syrian hamster in the home cage leads to failure to defend their own home territory even if the new intruder is smaller

Evokes stress response: elevated HPA activity, ACTH, CORT and decreased T and prolactin

Physiological and behavioral responses can last up to 33d and maybe through adulthood

Few female hamsters exhibit CSD, display low levels of submissive or defensive behaviors, results only last through the first test.
Strong sex difference.

CSD in males is a profound and persistent behavioral change

Hormones & Behavior (6 decks)

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