Compensatory Ocular Movements in Maintaining Gaze

Abstract

Stabilization of the retinal image during head movements could be performed by reflex oculomotor control by the visual, vestibular and neck proprioceptive systems. It has been known that the visual-oculomotor system primarily acts to maintain gaze when the frequencies of head movements are low (i. e. slow head movements), however, during high frequency head movements the vestibulo- and neck-oculomotor systems have a dominant role. Since the gain of neck-oculomotor reflex is low, the gaze performances during saccades are controlled mostly by way of the vestibulo-ocular reflex (Morasso et al., 1973). Bilateral labyrinthectomy in rheusus monkeys caused a gaze over-shoot up to 4-6 weeks after the operation (Dichgans et al., 1973). Author and others have reported that squirrel monkeys show an over-shoot of gaze during optokinetic stimulation at 3-4 weeks after bilateral lateral semicircular canal block. The over-shoot of gaze was subsided with similar time course in both of these experiments. Compensatory mechanisms underlying the recovery of the gaze, which occurred in CNS after the interference of vestibulo-ocular reflex, were discussed.