ROLE OF PURKINJE-CELLS IN THE VENTRAL PARAFLOCCULUS IN SHORT-LATENCY OCULAR FOLLOWING RESPONSES

We describe the simple-spike activity of Purkinje cells (P cells) in the ventral paraflocculus (VPFL) of behaving monkeys in association with movements of the visual scene that evoke short-latency ocular following responses. One group of P cells discharged maximally for downward motion, and the other for motion toward the side of the recording. The onset of the simple-spike response was measured in relation to the onset of ocular following in 24 P cells. The majority of P cells (79%) led by 1-9 ms. At the site of each recording, electrical stimuli (single negative pulses, 1.5-45 muA; 0.2 ms in width) were applied and 60% (18/30) of the sites elicited eye movements in the preferred direction of the P cells. The latency of the single-pulse-evoked response in the ipsilateral eye ranged from 8.6 to 10.9 ms. These data suggest that the P cells in the VPFL play a role in ocular following; some discharge early enough to generate the very earliest eye movements.