MODULATIONS OF THE OPTICAL-FLOW DID NOT INDUCE LOCOMOTOR PATTERN FLUCTUATIONS IN TREADMILL WALKING IN MAN

We report an analysis of gait during human treadmill walking when visu al information from the self-displacement velocity was modulated. Remo ving or sinusoidally modulating the frequency edge information in the optical flow did not induce significant changes in the walking velocit y as analyzed using Fast Fourier Transform or in the spatiotemporal ga it parameters. While low-frequency fluctuations in displacement speed increased, there was no significant change in locomotor cycle stabilit y. When a constant frequency edge was provided, i.e., when a backward optical flow was added, stride length decreased as compared to the no- optical-flow condition and instantaneous fluctuations in stride amplit ude increased. Temporal gait parameters did not change. These partial effects might be better explained by modifications in trunk balance. l n humans, modulation of velocity information on self-motion cannot ind uce unintentional modulation of walking velocity and did not enhance f luctuations in the locomotor pattern. These results argue against the proprioceptive role of sagittal visual-motion information in control o f stability of rhythmic leg movement, ar least when other propriocepti ve feedback sources are available.