The effect of alcohol on the vestibulo-ocular reflex and gaze regulation.

To clarify the effect of the temporary decline in cerebellar function on the vestibulo-ocular reflex (VOR) and gaze functions, we examined 12 normal adults under passive rotations before and after they drank alcohol at dosages of 0.43 and 0.65 g/kg. Whereas spatial gaze fixation was maintained accurately with 0.65 g/kg administration (0.06% blood alcohol level), gaze fixation on a head-fixed target and smooth pursuit were impaired by the higher dosage of 0.43 g/kg (0.03% blood alcohol). The magnitude of the alteration in the VOR gain after drinking was correlated significantly with the VOR gain before drinking: while small values were enhanced by drinking, large values were suppressed. The present study indicates that the VOR in the dark is regulated by the balance between the amplifying and suppressing forces controlled by the cerebellum.