Quantification of Visuo-vestibular Interaction up to 5.0 Hz in Normal Subjects

The gaze stability with respect to an earth-fixed target (compensatory eye movements) and a target moving with the subject (suppression of the vestibulo-ocular reflex) was investigated during high frequency sinusoidal rotation to obtain normative data on visuo-vestibular interaction. Induction coils were used to record eye and head movements. The transition from visually controlled eye movements at low frequencies to vestibular controlled eye movements at 5 Hz was clearly demonstrated during suppression. It was found that the influence of vision was not confined to the lower frequencies. Comparing suppression with the compensatory eye movements at 2.5 Hz, a gain reduction of about 35% and a phase lead of 30o was recorded. In contrast, at 5.0 Hz the visual environment did not influence the gain or phase of the eye movements. A gain value of 0.9 was found in both visual conditions.