Cerebellum and Oculomotor Control

The cerebellum plays a key role in the 'on-line' generation and the long-term calibration of all types of eye movements. The flocculus and paraflocculus assure that images are held steady on the fovea: impaired gaze holding, spontaneous vertical nystagmus, impaired pursuit and abnormal amplitude, and direction of vestibulo-ocular reflexes are signs of lesions here. The nodulus and ventral uvula modulate the amplitude and the axis of eye rotation of the response to the low-frequency (sustained) components of head rotation: prolonged vestibular responses and periodic alternating nystagmus are signs of lesions here. The dorsal vermis and underlying posterior fastigial nuclei calibrate saccade amplitude and pursuit initiation. Saccadic dysmetria is the hallmark sign of lesions here. The cerebellum also assures that both static and dynamic ocular alignment is optimized for binocular foveal vision.