INFLUENCE OF TARGET DISTANCE AND ACCELERATION LEVEL ON EYE-MOVEMENTS EVOKED BY LATERAL ACCELERATION STEPS

Lateral eye movements produced by linear acceleration along the inter- aural axis were studied in 6 normal subjects. They were seated upright , whole-body restrained, and were exposed to randomised rightward/left ward steps of 0.05 g, 0.1 g, 0.24 g of 600 ms duration. When viewing e arth-fixed targets at 30, 60 or 280 cm from their eyes, mainly pure co mpensatory slow-phase eye movements were evoked at latencies around 50 ms measured for the closest viewing distances. At onset, slow-phase a mplitude was modulated by acceleration and target distance. When the s ubjects were stationary and pursued moving targets at similar distance s and accelerations, latencies around 140 ms were observed, and catch- up saccades were frequently made. From these experiments, we defined t he dynamics of the otolith-ocular reflex for various levels of acceler ation and viewing distances.