Contribution of vision and cutaneous sensation to the control of centre of mass (COM) during gait termination.

This study employed manipulation of sensory inputs (vision and plantar-surface cutaneous sensation) during gait termination to elicit insight into the roles played by these sensory systems in the control of gait termination. Attenuation of cutaneous sensation was achieved through hypothermic anesthesia. Visual information was occluded using special glasses. The subjects were asked to walk along an 8 m walkway and during randomly selected trials (25% of trials) to terminate their gait in a predetermined area. The centre of mass (COM) was obtained in order to provide an indication of the efficiency and stability during termination when sensory inputs were manipulated. Lack of visual information delayed the initiation of the slowing down of the COM forward progression and increased the step length of the last step of termination. Additionally, lack of vision resulted in the COM moving closer to the base of support (BOS) during double support and more variability, in the COM, when attempting to achieve a final stable position. Insensitivity of the plantar-surface mechanoreceptors led to a longer second step and a more variable foot placement of the first step, and increased the loading rate during the final two steps of termination. Additionally when vision and cutaneous information were absent the resolution of the final stable position was not as effectively controlled. The results demonstrated that visual information about self-motion and object-motion and sensation from the plantar surface of the foot play phase-specific roles in the control of COM during gait termination.