Neurodevelopmental Shifts in Goal-Directed Behavior Across Adolescence

Abstract

This dissertation examines how adolescent brain maturation relates to the emergence of value-driven goal-directed behavior. This program of research aims to understand how functional brain development during adolescence may (a) influence the representation of value in the brain, and (b) guide the ability to successfully integrate value-based goals with cognitive demands to optimize performance. Paper 1 charts age-related differences in value representation of gain and loss outcomes in the brain. Findings reveal age-related asymmetries in gain and loss value coding in the striatum and anterior insula. Specifically, gain value coding in the striatum is modestly elevated in early adolescence, whereas mid-adolescence is accompanied by attenuated loss value coding in the anterior insula. Paper 2 examines how the ability to prioritize learning for high value goals changes during adolescence, and whether age-related differences in functional brain recruitment relate to motivational learning biases. The ability to learn from high and low value monetary gains and losses shifts across adolescence, such that younger adolescents prioritize learning for high-value losses whereas older adolescents prioritize learning for high-value gains. These behavioral changes are paralleled by age-related differences in the recruitment of value-selective signals in the ventral striatum during gain and loss learning. Paper 3 identifies age-related differences in value-guided cognitive control and examines neurodevelopmental mechanisms that may subserve age-related differences in goal-directed behavior. Results revealed that when high value incentives are at stake, young adults selectively enhance cognitive control performance, but adolescents do not. This late maturing behavior was mediated by age-related increases in functional connectivity between the ventral striatum and lateral prefrontal cortex, a neurodevelopmental mechanism that may account for the late adolescent emergence of successful goal-directed behavior. Together, these findings reveal that motivational biases shift during adolescence, and the ability to strategically upregulate cognitive performance for high value goals is a later developing feature that may be constrained by ongoing neurodevelopment.