OCULAR TORSION BEFORE AND AFTER 1 HOUR CENTRIFUGATION

To assess a possible otolith contribution to effects observed followin g prolonged exposure to hypergravity, we used video oculography to mea sure ocular torsion during static and dynamic conditions of lateral bo dy tilt (roll) before and after 1 h of centrifugation with a G(x)-load of 3 G. Static tilt (from 0 to 57 degrees to either side) showed a 10 % decrease in otolith-induced ocular torsion after centrifugation. Thi s implies a reduced gain of the otolith function. The dynamic conditio n consisted of sinusoidal body roll (frequency 0.25 Hz, amplitude 45 d egrees) about an earth horizontal and about an earth vertical axis (re spectively, ''with'' and ''without'' otolith stimulation). Before cent rifugation the gain of the slow component velocity (SCV) was significa ntly lower ''with'' otolith stimulation than ''without'' otolith stimu lation. Apparently, the contribution of the otoliths counteracts the o cular torsion response generated by the semicircular canals. Therefore , the observed increase in SCV gain in the condition ''with'' otolith stimulation after centrifugation, seems in correspondence with the dec reased otolith gain in the static condition.