Experience-dependent development of vagal circuitry in rodents and humans.

Given clear connections between mental and physical health, the impact of dysfunctional brain-body communication on emotional behavior and psychopathology is garnering increased attention. Vagal circuits comprise a major neural substrate for communication between the brain and peripheral organs, and evidence suggests that these circuits are developmentally plastic and sensitive to stress and other environmental challenges. Here, we review historic and current literature regarding how early life experience shapes the development of vagal circuitry in rodents and in humans. We discuss the anatomical intricacies of the sensory and motor vagal systems in rodents and outline their pre- and postnatal windows of developmental plasticity. We then focus on how two core features of early life experience, i.e., nutrition and maternal care, alter vagal circuit development in rodents. We discuss human studies that use differing psychological frameworks for measuring, interpreting, and contextualizing vagal contributions to the development of emotional control and stress response systems. We focus on infant, child, and adolescent research that test relations between parental care and/or early life adversity and vagal function, and how these factors impact emotional regulation and development of psychopathology. By synthesizing literature across species, we draw attention to novel insights and testable hypotheses that can be explored using different model systems. We emphasize the importance of considering environmental context and developmental timing for study design and interpretation of results. We conclude that vagal circuitry is an environmentally sensitive system for encoding stressful experiences during early life in rodents and in humans, with lifespan health consequences.