Affiliations: Aerospace Medical Research Unit, McGill University, Montreal, Canada
Note: [*] Reprint address: L.J.G. Bouyer, Aerospace Medical Research Unit, McGill University, 3655 Drummond Street, Montreal, PQ H3G 1Y6 Canada. Tel: (514) 398-6025; Fax: (514) 398-8241; E-mail: [email protected].
Abstract: Following a 30-minute exposure to an unusual motor strategy called “Torso Rotation” (TR), the signs and symptoms of motion sickness appear along with perceptual illusions during movement, gaze and postural instability, and a significantly reduced vestibulo-ocular response (VOR) gain. With repeated exposure to TR, the motion sickness disappears and gaze instability seems to be reduced. Is this apparent improvement in gaze stability associated with a reduction of the transient change in VOR gain? Motion sickness (subjective questionnaire) and VOR gain (passive step rotations in darkness) were measured before and repeatedly after TR on 7 consecutive days. Despite a complete loss of symptoms in 3 to 4 days, the transient, daily change in VOR gain remained unaffected. Furthermore, there was no increase in the use of compensatory saccades. It is concluded that adaptation to TR-induced motion sickness is not the result of a change in VOR's sensitivity to TR.
