[Childhood Social Isolation and Social Brain Development].

Abstract

Loneliness has a profound impact on mental health, and childhood loneliness is particularly detrimental to social development. In mice, juvenile social isolation disrupts adult social investigation and proper functioning of the prefrontal cortex. However, adult social isolation does not induce major social deficits, suggesting the existence of "social critical period." This critical period refers to the developmental window during which the brain exhibits high experience-dependent plasticity, leading to permanently altered wiring. Inappropriate environmental exposure during this critical period can cause lifelong abnormal neural circuit reorganization and atypical development. Clarification of the mechanisms underlying typical social development or aberrant formation of sociability during the critical period can enhance our understanding of the pathophysiology of various psychiatric disorders and pave the way for early detection and intervention. In this review, we present recent evidence from cross-species studies of the effects of juvenile social isolation on the maturation of social processing and the frontal cortex. Furthermore, we discuss how we can identify optimal intervention timing or detect novel therapeutic targets for psychiatric disorders from the perspective of the socially critical period by promoting a mechanistic understanding of the effect of childhood loneliness in animal models.