Inverse Dynamics Analysis of Head Stability during Predictable and Unpredictable Trunk Perturbation

INTRODUCTION As the head provides a reference frame for detecting and controlling motion via the visual and vestibular systems, it is desirable to keep it stable in space. While much is known about reflex and mechanical factors, little is known about predictive control. To determine the contribution of prediction to head stability in space (HSS) we asked two question. First, is HSS better for a perturbation applied at a known rather than unknown time? Second, is predictive control, represented by muscle torque at the neck, greater for a perturbation applied at known than an unknown time?