The Neuro-Environmental Loop of Plasticity: A Cross-Species Analysis of Parental Effects on Emotion Circuitry Development Following Typical and Adverse Caregiving

Early experiences critically shape the structure and function of the brain. Perturbations in typical/species-expected early experiences are known to have profound neural effects, especially in regions important for emotional responding. Parental care is one species-expected stimulus that plays a fundamental role in the development of emotion neurocircuitry. Emerging evidence across species suggests that phasic variation in parental presence during the sensitive period of childhood affects the recruitment of emotional networks on a moment-to-moment basis. In addition, it appears that increasing independence from caregivers cues the termination of the sensitive period for environmental input into emotion network development. In this review, we examine how early parental care, the central nervous system, and behavior come together to form a 'neuroenvironmental loop,' contributing to the formation of stable emotion regulation circuits. To achieve this end, we focus on the interaction of parental care and the developing amygdala-medial prefrontal cortex (mPFC) network-that is at the core of human emotional functioning. Using this model, we discuss how individual or group variations in parental independence, across chronic and brief timescales, might contribute to neural and emotional phenotypes that have implications for long-term mental health.