Cortical control of cerebellar dentato-rubral and dentato-olivary neurons

The cortical input of 117 dentate nucleus neurons projecting either to the red nucleus (73 cells) or to the inferior olive (44 units) was studied elec trophysiologically in rats. The majority of cells in both groups responded to electrical stimulation of discrete sites of the contralateral motor cort ex. However, activation latencies from the same cortical focus were shorter for neurons projecting to the red nucleus than for olivary-projecting neur ons. Principal components analysis pointed out significant differences betw een the two neuronal subgroups also in the temporal pattern of activity. Th ese results suggest that a motor command might:be transmitted through paral lel independent channels to cerebellar neurons projecting to different regi ons of the brainstem. (C) 1999 Lippincott Williams & Wilkins.