The Cerebellum and Striatum in Reward Processing: Caring About Being Right vs. Caring About Reward.

Emerging evidence indicates the cerebellum contributes to cognitive functions including social reward processing, yet its specific role relative to established reward regions like the ventral striatum remains undefined. We hypothesized the cerebellum would respond equivalently to both positive and negative social rewards. This prediction is grounded in classical findings that the cerebellum operates via supervised learning mechanisms that rely on error signals rather than traditional reward-based reinforcement. Using fMRI, we examined adolescents and young adults during a social prediction task where participants forecasted others' opinions of them and received accuracy feedback. Findings reveal that both the ventral striatum and a subregion of the posterior cerebellum (Crus I and II) were sensitive to social rewards. However, unlike the ventral striatum, the cerebellum exhibited a more uniform response to feedback, treating correct predictions about being liked and disliked in a similar manner. No age-related differences were observed. These findings suggest the cerebellum processes social rewards distinctly from the ventral striatum, likely reflecting its computational emphasis on prediction errors rather than reward valence. This functional distinction advances our understanding of cerebellar contributions to social cognition and learning mechanisms.