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

Adolescence is characterized by heightened reward sensitivity, novelty seeking, and risky decision-making. Prevailing neurodevelopmental frameworks typically attribute these behavioral trends to a maturational imbalance between rapidly developing striatal motivational neural circuits, and slower-maturing prefrontal cognitive control circuits. However, these models largely overlook the cerebellum--a structure boasting protracted development and dense, reciprocal connectivity with both the striatum and prefrontal cortex. Computational models highlight the cerebellum's central role in reinforcement learning and error-based model updating, positioning it as a potentially critical engine for 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 and frontoparietal cortico-cerebellar networks. Conversely, while reward receipt also elicits widespread cerebellar activation in adolescents, this is in stark contrast to the 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. The diffuse processing of reward outcomes suggests the adolescent cerebellum is actively building and refining internal forward models of affective responses within novel, probabilistic environments. Ultimately--rather than a biological epiphenomenon--it is hypothesized that this active cerebellar computation during adolescence may be fundamentally necessary to train prefrontal networks necessary for normative motivation and decision-making in adulthood.