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

Abstract

16The estimation of limbs' position is critical for motor control. While motor adaptation 17 changes the estimation of limb position in volitional arm movements, this has not been 18 observed in locomotion. We hypothesized that split-belt walking with the legs moving at 19 different speeds changes the estimation of the legs' position when taking a step. Thus, we 20 assessed young subjects' perception of step length (i.e., inter-feet distance at foot 21 landing) when they moved their legs (active perception) or these were moved by the 22 experimenter (passive perception).Step length's active, but not passive perception was 23 altered by split-belt walking; indicating that adapted efferent inputs changed the 24 perceived limbs' position without changing information from sensory signals. These 25 perceptual shifts were sensitive to how they were tested: they were observed in the 26 trailing, but not the leading leg, and they were more salient when tested with short than 27 long step lengths. Our results suggest that sensory changes following motor adaptation 28 might arise from mismatched limb position estimates from different sensory sources (i.e., 29 proprioception and vision), which is less prominent in walking. We also speculate that 30 split-belt walking could improve the deficient perception of step length post-stroke, 31 which contributes to their gait asymmetry impairing patients' mobility. 32 33