The Influence of Coriolis' Stimulation upon Stance Regulation

Abstract

To evaluate the influence of spatial orientation upon stance regulation, we gave Coriolis' stimulation to the subject standing on the turntable, and the findings were compared to those of eye movements.
Six healthy adult subjects were asked to wear goggles and stand on a force platform at the center of the turntable with legs together. They performed a forward head tilt (30 deg) while rotating at a constant velocity. Perturbations of body and eye movements were evaluated by shifts in the center of pressure and recordings by a CCD video camera, respectively.
Rotation velocity was increased by 15 deg/sec. None of the subjects touched the handrail of the turntable at rotation velocities less than 30 deg/sec. The center of pressure shifted to the left under clockwise rotation, and to the right under counterclockwise rotation. The direction of body perturbation resembled the direction of slow phase in induced nystagmus. The center of pressure shifted in the direction opposite to the physical force given to the head (Coriolis' force), that is, to the direction of transient movement of the spatial framework in the brain.
From the present study, it seems likely that spatial orientation plays an important role in regulating stance, and that posture is subjected to a simple rule, as eye movements are.