Granule cells rotate cortical trajectories to separate contexts
A study in mice using dual-site two-photon imaging shows premotor cortical L5PT neurons generalize across two skills with shared timing, while cerebellar granule cells remap their activity in time. Importantly, granule cell trajectories rotate coherently between contexts to separate them while preserving the cortical geometry, with larger rotations in expert animals, suggesting a division of labor: the cortex provides invariant dynamics for generalization and the granule cell layer reconfigures these dynamics to drive context-specific outputs.