ABSTRACT
Adolescence is a time of substantial development attributed to the maturation of brain circuits that underlie the
acquisition of new cognitive, emotional, and social skills. It is also a time of maximum vulnerability for mental
disorders. In the past decade, the incidence of anxiety, depression, and suicide increased by ~60% in
adolescents, remarkably more in females than in males. The social isolation during the COVID-19 pandemic
added to the severity of the national and international statistics. To fully address the current youth mental
health crisis, we need to understand how and why the dramatic reorganization of the adolescent brain
contributes to the increased vulnerability to mental disorders. The studies proposed here rest on the
assumption that the remodeling of the reward circuits of the brain creates the shared foundation of cognitive,
affective, and social maturation during adolescence. Our multifaceted project addresses foundational gaps in
our knowledge on how reward-driven motivational states inform adolescent behaviors such as risk-taking,
pleasure-seeking, impulsivity, and a range of emotional responses to challenges of the social environment. We
designed a within-subject, longitudinal study that spans the 2.5 - 3-year duration of adolescence in non-human
primates. During this period, we will obtain repeated samplings of neurophysiological data recorded from the
amygdala and orbitofrontal cortex in the context of the same behavioral tasks. In parallel, we will longitudinally
monitor morphometric and microstructural changes in the gray and white matter of the brain through serial MRI
scans, complemented by physical and hormonal measures of pubertal maturation. The three specific aims
address the neural basis of three different aspects of reward processing in the subcircuit of the amygdala and
orbitofrontal cortex. First, we will use a delay discounting task to determine the cellular and circuit level
changes that underlie the increasing tolerance (or lack thereof) for delayed rewards. Second, we use a social
reward-allocation task to test the neural underpinning of social reward processing in a self-oriented and an
other-oriented social frame of reference. Finally, we will determine where and how social status is processed in
the adolescent brain. Understanding social status relies on the ability to form abstract representations and is
also a prerequisite for the successful integration of the individual into a hierarchical adult social group. The
team, with combined expertise in human and non-human primate social behavior, neurophysiology,
neuroimaging, and endocrinology, will apply conceptually and technically innovative approaches to generate
unique and translational data, at both cellular and circuit levels, that account for the emerging cognitive,
affective, and social skills acquired during adolescence.