Abstract
Clinical and experimental reports have shown the functional role of the cerebellum in saccadic eye movement, and clinical tests in patients with cerebellar disorder have suggested that cerebellar function controlled the accuracy of saccadic eye movement in direction, amplitude and targetting. Therefore, participation of the cerebellum in eyemovement control was inferred from the effect of vermal and fastigial stimulation and from recordings of saccade-related activity form vermal lobules VI and VII (oculomotor vermis) and the fastigial nucleus (caudal part, fastigial oculomotor region, FOR).
Saccades evoked by microstimulation of the oculomotor vermis resulted from the activation of purkinje cells and their axons and movement toward the ipsilateral direction was evoked. Saccades evoked by stimulations the dorsal part of the fastigial nucleus were also in the ipsilateral direction and were suppressed by bicuculline. These saccades were induced by stimulations the axons of purkinje cells arising from the oculomotor vermis. Saccades evoked from the ventral part were in the contralateral direction, and were induced by direct stimulation of fastigial neurons. Saccades were the result of activating purkinje cells, indicating that signals of stimulation are transmitted via the fastigial nucleus. These purkinje cells and fastigial neurons received the same mossy fiber inputs with relation to saccades. Neural recordings from the oculomotor vermis and FOR suggested that these areas controlled saccades in the direction contralateral to the amplitude and ipsilateral to the ending saccades.
