Love is a powerful emotional experience that is rooted in ancient neurobiological processes shared with other species that pair bond. Considerable insights have been gained into the neural mechanisms driving the evolutionary antecedents of love by studies in animal models of pair bonding, particularly in monogamous species such as prairie voles (Microtus ochrogaster). Here, we provide an overview of the roles of oxytocin, dopamine, and vasopressin in regulating neural circuits responsible for generating bonds in animals and humans alike. We begin with the evolutionary origins of bonding in mother–infant relationships and then examine the neurobiological underpinnings of each stage of bonding. Oxytocin and dopamine interact to link the neural representation of partner stimuli with the social reward of courtship and mating to create a nurturing bond between individuals. Vasopressin facilitates mate-guarding behaviors, potentially related to the human experience of jealousy. We further discuss the psychological and physiological stress following partner separation and their adaptive function, as well as evidence of the positive health outcomes associated with being pair-bonded based on both animal and human studies.

Social experiences influence decision making, including decision making lacking explicit social content, yet mechanistic factors are unclear. We developed a new procedure, social incentivization of future choice (SIFC). Female mice are trained to nose poke for equally-preferred foods, then one food is paired with a novel conspecific, and the other with a novel object. Mice later respond more for the conspecific-associated food. Thus, prior social experience incentivizes later instrumental choice. SIFC is pervasive, occurring following multiple types of social experiences, and is not attributable to warmth or olfactory cues alone. SIFC requires the prelimbic prefrontal cortex (PL), but not the neighboring orbitofrontal cortex. Further, inputs from the basolateral amygdala to the PL and outputs to the nucleus accumbens are necessary for SIFC, but not memory for a conspecific. Basolateral amygdala→PL connections may signal the salience of social information, leading to the prioritization of coincident rewards via PL→nucleus accumbens outputs.