Sleep-state dependent cerebellar processing in adult mice

The cerebellum is important for motor performance and adaptation as well as cognition. Sleep is essential for optimizing of all these functions, but it remains to be elucidated how sleep affects cerebellar processing. It has been suggested that sleep periods with muscle twitches entrain the cerebellum with a copy of motor commands and subsequent sensory feedback signals, to develop predictive coding of movements. If this hypothesis is correct, one expects phasic correlations between the muscle twitches and specific features of the electro-encephalography (EEG) recordings in the cerebellum during various sleep stages as well as the climbing fiber activity in the cerebellar cortex, the modulation of which is relayed from the cerebral cortex via mesodiencephalic junction and inferior olive. Here we provide evidence for coherent correlations between cerebellar and cerebral cortical sleep spindles, twitches as well as patterns of climbing fiber activity. Our data are compatible with the novel concept that muscle twitches evoke complex spike synchronicity during NREM, which in turn affects cerebellar spindle activity and cerebellar-cortical information flow, thereby entraining an internal forward model.