The effects of ethanol on visual-vestibular interaction during active and passive head movements.

The effects on visual-vestibular interaction of a moderate dose of ethyl alcohol (blood alcohol 80 mg X 100 ml -1) have been investigated in two experiments. In the first, alcohol was shown to degrade both visual pursuit and suppression of the vestibulo-ocular reflex (VOR) in a similar manner when the vestibular response was induced by passive oscillation on a turntable at frequencies of 0.11-1.2 Hz. In the second experiment a similar degradation in VOR suppression was observed when subjects made volitional head movements at frequencies of 0.5-3 Hz. In addition, the effectiveness of vestibulo-ocular compensation was shown to be significantly reduced by alcohol when viewing an earth-fixed target during voluntary head movements. Although alcohol induced small changes in the vestibulo-ocular response recorded in darkness, the main effect on oculomotor performance was a reduced effectiveness in the visual feedback of retinal error information.