PROJECT SUMMARY/ABSTRACT This project combines the expertise of Dr. Katalin Gothard at The University of Arizona [US] and Dr. Anna W. Roe at Zhejiang University [China]. The aim of this project is to understand changes in the brain underlying the emergence of social and emotional regulation during adolescence. Adolescence is a period of accelerated social and cognitive development, and also a time of enhanced vulnerability for anxiety and impulse-control disorders, which elevate the lifelong risk for secondary psychiatric disorders. During this period, the prefrontal cortex undergoes maturation, but little is known about the maturation of its relationship with the amygdala, considered a hub of emotional processing in the brain. In humans and nonhuman primates, the amygdala matures long before puberty; in early adolescence, emotional processes and arousal governed by the amygdala dominate emotional and social behavior. As the prefrontal cortex matures and increases its influence on amygdalar function, emotional behavior becomes more regulated. We hypothesize that the development of emotional regulation during adolescence is due to changes in amygdala-prefrontal networks. The goal of this proposal is to monitor longitudinally, in the same individuals, the reorganization of functional connections between the amygdala and the PFC. This will be accomplished by a multimodal approach of laser-fMRI functional tract tracing, and neurophysiological recordings in the amygdala and the prefrontal cortex. In parallel, punctate administration of behavioral tasks will provide a measure of longitudinal changes in impulsivity and sociability. The fMRI, neurophysiological, and behavioral measures will be correlated at matched timepoints, thereby achieving a multiscale (cellular to circuit level to behavior) understanding of adolescent development. The findings from this study will have significant bearing on our understanding of normal adolescent brain development and also of the possible risk factors for the emergence of social misadjustment and mental disease.