Cerebellar Purkinje cells can differentially modulate coherence between sensory and motor cortex depending on region and behavior

Abstract

Coherence among sensory and motor cortices is indicative of binding of critical functions in perception, motor planning, action and sleep. Evidence is emerging that the cerebellum can impose coherence between cortical areas, but how and when it does so is unclear. Here, we studied coherence between primary somatosensory (S1) and motor (M1) cortices during sensory stimulation of the whiskers in the presence and absence of optogenetic stimulation of cerebellar Purkinje cells in awake mice. Purkinje cell activation enhanced and reduced sensory-induced S1-M1 coherence in the theta and gamma bands, respectively. This impact only occurred when Purkinje cell stimulation was given simultaneously with sensory stimulation; a 20 ms delay was sufficient to alleviate its impact, suggesting the existence of a fast, cerebellar sensory pathway to S1 and M1. The suppression of gamma band coherence upon Purkinje cell stimulation was significantly stronger during trials with relatively large whisker movements, whereas the theta band changes did not show this correlation. In line with the anatomical distribution of the simple spike and complex spike responses to whisker stimulation, this suppression also occurred following focal stimulation of medial crus 2, but not of lateral crus 1. Granger causality analyses and computational modeling of the involved networks suggest that Purkinje cells control S1-M1 coherence most prominently via the ventrolateral thalamus and M1. Our results indicate that coherences between sensory and motor cortices in different frequency ranges can be dynamically modulated by cerebellar input, and that the modulation depends on the behavioral context and is site-specific. Significance StatementCoherent activity between sensory and motor areas is essential in sensorimotor integration. We show here that the cerebellum can differentially affect cortical theta and gamma band coherences evoked by whisker stimulation via a fast ascending and predictive pathway. In line with the functional heterogeneity of its modular organization, the impact of the cerebellum is region-specific and tuned to ongoing motor responses. These data highlight site-specific and context-dependent interactions between the cerebellum and the cerebral cortex that can come into play during a plethora of sensorimotor functions.