Mesoscale Ca2+ imaging reveals networks of Purkinje cell dendritic and somatic modulation, with divergent roles of activity versus correlation during behavior

A major challenge in cerebellar physiology is determining how the stereotypic, conserved circuitry of the cerebellar cortex, with its dominant parasagittal and transverse architectures, underlies its fundamental computations and contributions to behavior. To interrogate Purkinje cell dynamics at this parasagittal and transverse spatial scale, we implemented a novel approach for awake, chronic, wide-field Ca2+ imaging of the cerebellar cortex. We observe two functionally and spatially distinct Purkinje cell networks, reflecting their dendritic and somatic activities, respectively. Both dendritic and somatic networks exhibit bilateral, widespread activation during behavior, but with diverse patterns of spatial correlations occurring primarily along the parasagittal and transverse directions, consistent with the main geometry of the cerebellar cortex. Somatic network correlation dynamics are robustly modulated by prediction errors, and even reflect ultimate behavioral outcomes. These results provide a novel link between cerebellar structure and function, with the correlation dynamics of Purkinje cell activity a key feature.