Extended amygdala orchestrates social motivation in socially isolated mice.

Juveniles deprived of social contact for an extended period of time demonstrate a broad range of adverse effects on behavior, including increased social aversion. Employing our recently developed integrative assay to assess social aversion, we discovered that social isolation is sufficient to induce decreases in social motivation and increases in social fear and hesitancy. Unsupervised behavioral analyses revealed that social aversion in isolated mice is largely driven by an inflexible, anxiety-like state marked by heightened social vigilance. Using intersectional, projection-specific neural circuit perturbations and in vivo imaging, we discovered that isolation-induced decreases in social motivation are governed by an underexplored projection from the anterodorsal bed nucleus of the stria terminalis (adBNST) to the nucleus accumbens (NAc). These findings illustrate the complexity with which juvenile isolation serves to negatively impact social behavior and identify a novel circuit through which animals integrate information about social state to orchestrate changes in social motivation.