1518 Functional dissociation within the cerebellum: motor execution and sensori-motor readiness

NORIICHI MANO, YUMI ITO, HIDETOSHI SHIBUTANI We found visuomotor type saccade-related Purkinje cells in the posterior cerebellar hemisphere of the monkey, in addition to the motor type saccade-related Purkinje cells which we have already reported. The visuomotor type Purkinje cells have two component of discharges: the one is the visual component which responded with constant latency of 60 milliseconds to the jump of a fixation light spot from a center to either 20 degrees up, down, left or right directions. The other is the motor component which shows the same discharge characteristics as the discharges of motor type Purkinje cells, i.e., the discharge rate begins t.o change 80 to 20 milliseconds prior and time-locked to the onset of saccades. The visuomotor type Purkinje cells were found in the posterior region of Crus IIa, intermingled with the motor type Purkinje cells.