Social bonding is mediated several brain areas which respond to OT, AVP, and DA. Studies using fMRI have been used in research to assess associated brain areas in human attachment based on auditory and visual stimuli responses of the brain to attachment target. These studies found that the ventral tegmental area (VTA) and ventral striatum in the brain were activated during responses to attachment target. Further research in fMRI studies have shown that the amygdala, nucleus accumbens (NA), hypothalamus, sub-cortical and cortical reward neural networks are also involved mediating social attachment. These networks and pathways contain receptors that allow OT, AVP, and DA to exert their effects in high and low level processes in the brain that provide a foundation for social trust. In studies with human subjects who experienced social isolation, there was an increase in activity in the hypothalamic-pituitary-adrenal (HPA) axis-a neural network involved in the release of cortisol, a stress-response hormone. This same research showed a deactivation in brain regions associated with OT and AVP.
