1. Brain neuroplasticity and behavioral development in adolescence

Adolescence is widely conceptualized as a period of time when individuals engage in more risk-taking behavior, at least as compared to childhood and adulthood. The reasons for this increase have not been fully explained from a scientific perspective. Within our lab, we are investigating the longitudinal development of executive functions, such as working memory, planning, and inhibitory control, in typically-developing adolescents as a function of both age and pubertal development. The literature suggests that these abilities improve at a steady rate through adolescence and into adulthood.

We are also examining brain structure in relation to the development of executive function.  Brain-based changes commonly observed through adolescence include declines in cortical gray matter, declines in cortical thickness, increases in white matter extent, and evidence of increased fronto-striatal connectivity. In our work, we have attempted to define links between these normative neurodevelopmental processes and behavior.

In recent years, models of adolescent development have expanded from a primary focus on executive function and its development to the consideration of motivational factors that also impact behavior. In our lab, we are most interested in positive motivation--that is, the circumstances under which people pursue positive goals and rewards. Our group has theorized that positive motivation has a basis in the brain’s dopamine system, and our group has described the circuitry involved in this association. We have hypothesized that increases in dopamine activity underlie a shift that occurs during adolescence where sensitivity to positive incentives increases before declining to more typical levels as adulthood is reached. Our work coheres with other dual systems models of adolescent development in suggesting (a) that adolescence is a period of time when positive incentive motivation exerts a strong influence over behavior and (b) that this drive is difficult for the still-developing prefrontal cortex to fully control. This work has implications for many forms of psychopathology that emerge during adolescence.