Direction-selective saccadic-burst neurons in the fastigial oculomotor region of the macaque.

Discharges of 68 neurons, recorded from the oculomotor region of the fastigial nucleus (FN) of the macaque, were characterized by a burst which started approximately 20 msec prior to the onset of a saccade in a direction contralateral to the recording site. These fastigial neurons also paused before saccades in their nonpreferred direction and then discharged with a subsequent burst. All units were spontaneously active but the tonic level of activity did not reflect eye position. They aggregated within the oculomotor region and the firing of 57 units (83.8%) was suppressed by stimulation of vermal lobule VII. Tonic discharges of six other units were closely related to eye position and located rostral to the burst units. Discharges of 16 units increased during the ipsilateral phase of sinusoidal head rotation and those of 50 units increased during contralateral head rotation. These neurons did not show saccade-related activity. They were widely scattered in the rostral and central portions of the FN. None of these units was inhibited by stimulation of vermal lobule VII.