Interlimb coordination evoked by unilateral mechanical perturbation during body-weight supported gait.

During locomotion, motor strategies can rapidly compensate for any obstruction or perturbation that could interfere with forward progression. Here we studied the contribution of interlimb pathways for evoking muscle activation patterns in the case where body weight is externally supported and vestibular feedback is limited. The experiments were conducted using a novel device intended for gait therapy: the MIT-Skywalker. The subject's body weight was supported by an underneath saddle-like seat, and a chest harness was used to provide stabilization of the torso. Eight neurologically healthy individuals were asked to walk on the MIT-Skywalker, while one side of its split belt treadmill was unexpectedly dropped either before heel-strike or during mid-stance. Leg kinematics will be reported. We found that unilateral perturbations evoked responses at the contralateral limb, which were observed in both kinematic and neuromuscular level. The latency of most responses exceeded 100 msec, which suggests a supraspinal (i.e. not local) pathway.