S11-3. Neurophysiological basis of body-weight supported step training

Abstract

The body-weight supported step training (BWSS) has been originally applied to individuals with spinal cord injury (SCI) on the basis of numerous experimental evidences indicating that the central pattern generator (CPG) of quadruped animals can be reorganized and allows those animals walk independently after BWSS training. However, beside the fact that the CPG alone cannot provide full weight-bearing force and stepping in human, it is not known whether the other factors such as central command and sensory afferent information are involved in restoration of bipedal walking especially after incomplete SCI. To address this issue we have conducted a series of experiments, which aimed to reveal effects of both sensory inputs and descending commands on excitability modulation of neural circuits involving human bipedal locomotion. By using the Lokomat robotic gait trainer, we tested effects of sensory inputs on corticospinal (CS) excitabilities during assisted stepping. The results so far demonstrate that sensory inputs, especially body-weight related somatosensory input, have a facilitatory effect on CS pathway of an ankle flexor muscle, whereas those sensory inputs regardless of body-weight related or not have an inhibitory effect on spinal stretch reflex circuits of upper and lower limb muscles during the assisted stepping.