On the interlimb coordination and synchronization during gait.

Human locomotion is based on the finely tuned coordination of the two legs. For this research, we studied the contribution of interlimb pathways for coordinating and synchronizing the legs' motion 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. Two neurologically healthy individuals were asked to walk on the MIT-Skywalker, while one side of its split belt treadmill was unexpectedly dropped during the perturbed leg stance phase. Leg kinematics are reported as well as the effect of the timing of perturbation on the unperturbed leg. Presented here are the phase-response curves (PRCs) for both legs. We found that unilateral perturbations evoked responses at the contralateral limb, while the timing of the activation played a significant role in those responses.