The cerebellum exploits a thalamic carrier frequency to refine motor behaviors.

Despite enabling nearly all cerebellar-cortical communication, how the thalamus processes and interacts with cerebellar activity remains unclear. We found a pronounced 1-5 Hz (delta) rhythm in the thalamic membrane potential and cerebellothalamocortical local field potentials during nonmoving periods in behaving mice. We show, using photometry, multielectrode recordings, closed-loop stimulation, and dynamic clamp, that CaV3.1-dependent resonance of thalamic neurons facilitates transmission of delta-rhythm cerebellar activity to the cortex. Knockout of CaV3.1 in cerebellar-thalamic neurons diminishes the thalamocortical delta oscillation and specifically impairs motor learning while minimally affecting motor performance. These results ground population oscillations to features of ion channels, highlight the cerebellum and delta's utility in offline motor learning, and support a carrier frequency-like encoding mechanism that underlies cerebellothalamocortical communication.