Split-Belt walking induces changes in active, but not passive, perception of step length

Abstract

The estimation of limbs position is critical for motor control. While motor adaptation changes the estimation of limb position in volitional arm movements, this has not been observed in locomotion. We hypothesized that split-belt walking with the legs moving at different speeds changes the estimation of the legs position when taking a step. Thus, we assessed young subjects perception of step length (i.e., inter-feet distance at foot landing) when they moved their legs (active perception) or these were moved by the experimenter (passive perception). Step lengths active, but not passive perception was altered by split-belt walking; indicating that adapted efferent inputs changed the perceived limbs position without changing information from sensory signals. These perceptual shifts were sensitive to how they were tested: they were observed in the trailing, but not the leading leg, and they were more salient when tested with short than long step lengths. Our results suggest that sensory changes following motor adaptation might arise from mismatched limb position estimates from different sensory sources (i.e., proprioception and vision), which is less prominent in walking. We also speculate that split-belt walking could improve the deficient perception of step length post-stroke, which contributes to their gait asymmetry impairing patients mobility.