The effects of galvanic stimulation on the human vestibulo-ocular reflex

We studied the effects of 5 mA bilateral or unilateral, bipolar or monopola r, galvanic stimulation on the horizontal vestibuloocular reflex (hVOR) in six normal subjects during 0.01, 0.05, 0.1, 0.5 and 1 Hz yaw rotations and in two subjects during high-acceleration, low-amplitude yaw head rotations (head impulses). Bipolar galvanic stimulation induced horizontal nystagmus in all subjects and an asymmetry of the hVOR only during rotations below 0. 1 Hz. Monopolar stimulation had no significant effect. The findings suggest that in humans galvanic stimulation affects those primary horizontal semic ircular canal neurons that mediate the hVOR via indirect pathways through t he velocity storage mechanism. NeuroReport 11:3897-3901 (C) 2000 Lippincott Williams & Wilkins.