Visual-vestibular interaction: Effect of prolonged stimulation on the vestibulo-oculomotor reflex responses

The effect of prolonged (8-h) visual, vestibular, or visual-vestibular stimulation was studied on the vestibulo-oculomotor reflex (VOR) response in a group of normal rabbits. Continuous visual-vestibular stimulation was the most effective method to increase the magnitude of the VOR response. Visual stimulation alone was less effective and vestibular stimulation decreased the VOR response. Visual-vestibular stimulation under conditions of monocular vision produced changes in the VOR response that depended on the direction of motion and on the eye stimulated. The VOR response was increased in the direction of the maximum response, namely, rotations that produced relative displacement of the surroundings in the temporalnasal direction of the visual field. The effects of prolonged visual-vestibular stimulation led to more than double the magnitude of the VOR during the experimental session. Unilateral asymmetrical visual-vestibular stimulation led to asymmetrical VOR responses associated with typical signs of peripheral vestibular imbalance, such as nystagmus and postural changes.