Abstract
The role of the cerebellum in social learning remains poorly understood. Although the cerebellar posterior lobe (CPL) has been implicated in social decision-making and autistic traits, its contribution to social prediction and prediction-error (PE) processing during learning is unclear. We focused on adolescence, a critical developmental period for social decision-making and learning. 71 autistic (AUT) and 75 non-autistic (N-AUT) participants completed social and non-social learning tasks during fMRI. Preregistered hypotheses predicted that the CPL would be involved in prediction and PE processing, with effects differing by diagnostic status and age.We found no group differences in social learning. Across participants, PEs decreased more steeply during non-social than social learning; in the AUT group this difference between social and non-social learning was more pronounced. In the cerebellum, PE-related activity in the CPL (lobules Crus I/II, VI, and VIIb) showed group- and age-related differences. Contrary to our hypothesis, PE-related activity during social learning was greater in AUT than N-AUT participants in right Crus II. Across several other CPL regions, PE-related activity increased with age in N-AUT participants but showed the opposite pattern in AUT participants. Mirroring the marginally steeper behavioral PE reduction in the non-social condition in the AUT vs. the N-AUT group, PE-related brain activity was greater for non-social than social PEs in left Crus I and right lobule VI in the AUT group. Exploratory searchlight analyses showed greater PE-related connectivity between left Crus II and prefrontal cortex in AUT than N-AUT participants. These findings suggest that AUT adolescents may engage CPL differently during learning, particularly for social versus non-social information. Greater CPL activity and connectivity during social learning in AUT may reflect compensatory mechanisms supporting comparable behavioral performance to N-AUT youth.