Role of Purkinje cells in the ventral paraflocculus in short-latency ocular following responses

We describe the simple-spike activity of Purkin je 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 re sponses. 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 re sponse 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 A; 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.