Oscillatory activity in the cerebellar hemispheres of unrestrained rats.

We recorded multiunit neural activity in the granule cell layer of cerebellar folium Crus IIa in unrestrained rats. Seven- to 8-Hz oscillatory activity was seen during behavioral states in which the animal was immobile; any movement the animal made coincided with termination of the oscillations. However, nearly one-third of oscillatory episodes appeared to cease spontaneously, in the absence of any observable sensory input or movement. Oscillations were synchronized both within and between cerebellar hemispheres, demonstrating precise temporal coordination among multiple, bilateral levels of the somatosensory system. We interpret these data in the context of similar oscillations observed in other brain structures and suggest that the oscillations are an underlying dynamic property of the entire somatosensory network.