Corollary discharge in precerebellar nuclei of sleeping infant rats

In week-old rats, somatosensory input arises predominantly from external stimuli or from sensory feedback (reafference) associated with myoclonic twitches during active sleep. A previous study suggested that the brainstem motor structures that produce twitches also send motor copies (or corollary discharge, CD) to the cerebellum. We tested this possibility by recording from two precerebellar nuclei—the inferior olive (IO) and lateral reticular nucleus (LRN). In most IO and LRN neurons, twitch-related activity peaked sharply around twitch onset, consistent with CD. Next, we identified twitch-production areas in the midbrain that project independently to the IO and LRN. Finally, we blocked calcium-activated slow potassium (SK) channels in the IO to explain how broadly tuned brainstem motor signals can be transformed into precise CD signals. We conclude that the precerebellar nuclei convey a diversity of sleep-related neural activity to the developing cerebellum to enable processing of convergent input from CD and reafferent signals.

It’s not you, it’s me: Corollary discharge in precerebellar nuclei of sleeping infant rats

In week-old rats, somatosensory input arises predominantly from stimuli in the external environment or from sensory feedback associated with myoclonic twitches during active (REM) sleep. A previous study of neural activity in cerebellar cortex raised the possibility that the brainstem motor structures that produce twitches also send copies of motor commands (or corollary discharge, CD) to the cerebellum. Here, by recording from two precerebellar nuclei—the inferior olive and lateral reticular nucleus—we demonstrate that CD does indeed accompany the production of twitches. Within both structures, the CD signal comprises a surprisingly sharp activity peak within 10 ms of twitch onset. In the inferior olive, this sharp peak is attributable to the opening of slow potassium channels. We conclude that a diversity of neural activity is conveyed to the developing cerebellum preferentially during sleep-related twitching, enabling cerebellar processing of convergent input from CD and reafferent signals.