Neuroscience of animal pair bonding

Animal pair bonding is the process of developing a pair bond, is the strong affinity that develops in some [[species between the male and female in a breeding pair.  Pair-bonding, from 1940, is a term frequently used in sociobiology and evolutionary psychology circles and is typically meant to imply either a life-long monogamous relationship or a stage of mating interaction in socially monogamous species.

Research in both neuroanatomy and neurochemistry is attempting to identify the biological processes which are associated with this behavior.

Findings
Monogamous voles, such as prairie voles, found to have significant differences in the density and distribution of vasopressin receptors in their brain when compared to polygamous voles. These differences are located in the ventral forebrain and the dopamine-mediated reward pathway.

Both vasopressin and dopamine act in this region to coordinate rewarding activities such as mating, and regulate selective affiliation. These species specific differences have shown to correlate with social behaviors, and in monogamous prairie voles are important for facilitation of pair bonding. Pair bonding is also seen between individuals of the same sex, as demonstrated by behavior similar to that of male-female pair-bonded individuals.

Issues
From the above it can be seen that it is difficult to distinguish between neurological changes due to pairings made for mating purposes and those arising from other forms of attachment.