Vestibular perception of passive whole-body rotation about horizontal and vertical axes in humans: goal-directed vestibulo-ocular reflex and vestibular memory-contingent saccades.

This study was aimed at complementing the existing knowledge about vestibular perception of self-motion in humans. Both goal-directed vestibulo-ocular reflex and vestibular memory-contingent saccade (VMCS) tasks were used, respectively as concurrent and retrospective magnitude estimators for passive whole-body rotation. Rotations were applied about the earth-vertical and earth-horizontal axes to study the effect of the otolith signal in self-rotation evaluation, and both in yaw and pitch to examine the horizontal and vertical semi-circular canals. Two different magnitudes of constant angular acceleration (50 degrees/s2 and 100 degrees/s2) were used. The main findings were (1) strong correlation between both oculomotor responses of both tasks, (2) greater accuracy with rotations about the earth-vertical than the earth: -horizontal axis, (3) greater accuracy for yaw than for pitch rotations, (4) greater accuracy for high acceleration than for low, and (5) no effect of the delay (2 s or 12 s) in the VMCS task. Adequacy of both tasks as subjective magnitude estimators of vestibular perception of self-motion is discussed.