Protracted prediction: Neurodevelopment of reward processing in the adolescent cerebellum.

Adolescence is characterized by heightened reward sensitivity and risky decision-making. Prevailing neurodevelopmental frameworks typically attribute these behavioral trends to a maturational imbalance between rapidly developing motivational brain regions, and slower-maturing prefrontal cognitive control circuitry. However, these models largely overlook the cerebellum--a structure that demonstrates protracted development across adolescence and reciprocal connectivity with both striatum and prefrontal cortex. Computational models also highlight the cerebellums central role in reinforcement learning and error-based model updating, making it a potentially critical region for understanding adolescent reward processing. To evaluate this, we conducted a systematic literature search and coordinate-based meta-analysis of functional magnetic resonance imaging (fMRI) studies examining reward anticipation and receipt in healthy adolescents (19 studies; 55 cerebellar peaks). Results demonstrate a striking functional dissociation. During reward anticipation, adolescent cerebellar activation mirrors adult topographies--demonstrating widely distributed activation patterns across the cerebellar lobules and Vermis, localized to cerebellar regions that are functionally connected with salience, somatomotor, and frontoparietal cortico-cerebellar networks. Conversely, while reward receipt also elicits widespread cerebellar activation in adolescents, this stands in contrast to highly focal feedback-locked reward activity seen only in the Vermis in adult studies. We interpret these findings through the lens of cerebellar reinforcement learning. We argue that widespread reward outcome-locked BOLD activity in adolescents may reflect broader parallel fiber recruitment, supporting the active maintenance of short-timescale eligibility traces required for credit assignment while internal forward models are being constructed during development. Ultimately--rather than a biological epiphenomenon--it is hypothesized that this active cerebellar computation during adolescence may contribute to the developmental shaping of prefrontal networks necessary for normative regulation of motivation and decision-making in adulthood.