Neural Circuits of Social and Physiological Needs

Physiological needs, such as the need for food, water, and sleep, are fulfilled through homeostatic processes by which brain circuits monitor changes in internal states and trigger goal-directed behaviors, such as eating, drinking, and sleeping, that are aimed to restore physiological balance. Increasing evidence, in humans and animals alike, points to social interaction as yet another fundamental need regulated by homeostatic processes. In this review, we highlight recent efforts to identify neuronal circuits and cell populations underlying social drive, social satiety, and overall social homeostasis, and we compare newly identified neural and molecular mechanisms governing social and physiological needs. We summarize shared and distinct features across distinct needs at the levels of behavioral expression, neuronal circuit function, molecular mechanisms, and sensory modulation. Findings across distinct homeostatic systems offer broad insights into the organizational principles of homeostatic regulation and lay ground for new avenues of research on the brain response to social isolation.