Social Bonding

Affiliation encompasses social bonding between individuals, including sexual partner relationships and parent-infant relationships.

• Approach the thing you're affiliating with
• Learn its identity
• Invest in this individual whilst rejecting others

• An important sensory modality for social processing in animals is olfaction
• Pheromones are secreted or excreted chemical factors that trigger a social response in members of the same species
• The vomeronasal organ detects pheromones and relays the information to the accessory olfactory bulb (AOB)
• But Humans don't appear to have one of these..

• Part of the recognition task
• The ability to recognise another thing
• Investigated using animals: a subject animal is exposed to a stimulus animal and after a predetermined period of time is either re-exposed to the same stimulus animal or to a novel stimulus animal.
• Typically the animal spends more amount of time investigating the novel animal.

• Also part of the recognition task
• The ability to discern something from a group of others
• On re-exposure, the animals are presented simultaneously, forcing the subject to choose between the two.

• Montane voles (non-monogamus) and praire voles (monogamus) have different distributions of oxytocin receptors in the brain, particularly in the nucleus accumbens. 
• They also have different distribution of vasopressin receptors in the brain, specifically in the ventrum pallidum.
• Male or females are injected with antagonists to vasopressin and oxytocin 
• The antagonists (blocking molecules) do not alter mating behaviour per se, but seem to prevent the partner preference that normally occurs with mating in prairie voles

• Oxytocin and vasopressin 
• Produced in the hypothalmus 
• Transported to the posterior pituitary gland were they are released into the bloodstream

• Yes, intranasal infusion of oxytocine increases performance in a facial recognition test
• Intranasal infusion of vasopressin in subjects did not affect their attention but their response to neutral faces were similar to the response of control subjects to angry faces.

• Children with ASD show decreased oxytocine in their blood cirulation.
• Affected gene expression of oxytocin and vasopressin genes (Otr and Avpr).
• Nasal infusions of oxytocin has been found to improve emotion recognition in faces and decreases repetitive behaviours.

• Sort of 
• In laboratory mice, infanticide is commonly observed in virgin males.
• Males stop committing infanticide and become paternal toward pups in a transient period after mating with a female, starting at the approximate time of birth and continuing until the weaning of pups
• Similar pattern in wild female mice has been observed, but laboratory female mice do not show aggressive behaviour to pups

• Time-dependent synaptic or transcriptional change triggered by mating, as well as the chemical cues released by females during pregnancy, have been hypothesized to drive the radical behavior shift from infanticide to parental behavior
• Disruption to the vomeral nasal organ leads to a marked reduction in pup-directed aggression and to the emergence of parental care in virgin males
• Also seen in species including burying beetles and birds
• The changes in levels of female hormones such as estrogen, progesterone, and prolactin through pregnancy have long been implicated in the regulation of maternal behavior (testosterone levels decrease during fatherhood, such as in humans, frogs, and fish)

• Parental care
• Pup avoidance/aggression
• These circuits involve subcortical nuclei + the prefrontal cortex (PFC)

• In male and most female virgin rats, the aversive circuit is dominant and suppresses parental care
• Whereas in postpartum and “sensitized” females, hormonal, neuromodulatory, and experience-dependent factors activate the facilitative circuit and silence the avoidance circuit.
• Oxytocin is involved in the initation of the maternal behaviourThe ventral tegmental area (VTA) of the dopamenergic system appears to be involved in initiating and maintaing maternal behaviour in rats
• Noradrenergic and seretonergic circuits also appear to be involved in material behaviours

• In non-human animals, the motivational aspect of attachment can be assessed as proximity seeking, a social preference or a separation response.
• In humans, the ultimate form of this motivation would be called “love”.