ABSTRACTAdolescence is a time of substantial development attributed to the maturation of brain circuits that underlie theacquisition of new cognitive emotional and social skills. It is also a time of maximum vulnerability for mentaldisorders. In the past decade the incidence of anxiety depression and suicide increased by ~60% inadolescents remarkably more in females than in males. The social isolation during the COVID-19 pandemicadded to the severity of the national and international statistics. To fully address the current youth mentalhealth crisis we need to understand how and why the dramatic reorganization of the adolescent braincontributes to the increased vulnerability to mental disorders. The studies proposed here rest on theassumption that the remodeling of the reward circuits of the brain creates the shared foundation of cognitiveaffective and social maturation during adolescence. Our multifaceted project addresses foundational gaps inour knowledge on how reward-driven motivational states inform adolescent behaviors such as risk-takingpleasure-seeking impulsivity and a range of emotional responses to challenges of the social environment. Wedesigned a within-subject longitudinal study that spans the 2.5 - 3-year duration of adolescence in non-humanprimates. During this period we will obtain repeated samplings of neurophysiological data recorded from theamygdala and orbitofrontal cortex in the context of the same behavioral tasks. In parallel we will longitudinallymonitor morphometric and microstructural changes in the gray and white matter of the brain through serial MRIscans complemented by physical and hormonal measures of pubertal maturation. The three specific aimsaddress the neural basis of three different aspects of reward processing in the subcircuit of the amygdala andorbitofrontal cortex. First we will use a delay discounting task to determine the cellular and circuit levelchanges that underlie the increasing tolerance (or lack thereof) for delayed rewards. Second we use a socialreward-allocation task to test the neural underpinning of social reward processing in a self-oriented and another-oriented social frame of reference. Finally we will determine where and how social status is processed inthe adolescent brain. Understanding social status relies on the ability to form abstract representations and isalso a prerequisite for the successful integration of the individual into a hierarchical adult social group. Theteam with combined expertise in human and non-human primate social behavior neurophysiologyneuroimaging and endocrinology will apply conceptually and technically innovative approaches to generateunique and translational data at both cellular and circuit levels that account for the emerging cognitiveaffective and social skills acquired during adolescence.