Time course of gaze influences on postural responses to neck proprioceptive and galvanic vestibular stimulation in humans.

We have previously shown that postural responses to vibration of neck dorsal muscles (NS) and to galvanic stimulation of the vestibular system (GS) are influenced by the direction of gaze. Here, we describe the time course of this effect. We found that eye orienting movements during NS induce shifts of body inclination toward the direction of gaze with a latency of about 2 s: the time course is smooth and a steady state is attained after about 5 s from eye movements. If eye eccentricity is maintained and NS or GS are sequentially repeated for as long as 2 min, the direction of sway drifts in the direction opposite to eye deviation. The findings reveal that the frames of reference for the control of posture may have a dynamic nature.