Striatal influences on paravermal cerebellar activity.

Units were recorded extracellularly in paravermal cortex (lobule VI) of the cerebellum of chloralose anesthetized cats. Electrical stimulation of the striatum evoked excitation followed by inhibition in these neurons. In addition, the somatosensory properties of these cells were also affected by the striatum. A conditioning-test paradigm (C-T) was used in which conditioning stimulation was applied to the striatum. Test responses were evoked in cerebellar neurons by facial stimulation. As a function of the C-T interval, striatal stimulation could either enhance or suppress the test facial responses. In another procedure, a moveable electrode was used to map the thresholds for affecting the cerebellum from different points in the striatum. The lowest mean threshold was in the putamen followed respectively by the internal capsule and caudate nucleus. Control experiments suggested that striatal effects on the cerebellum were due neither to extra-striatal current spread nor antidromic activation of corticostriatal fibers. These data were discussed with regard to models of striatal motor functioning that indicate a role in postural control and sensory gating.