Cortical and Spinal Excitability Changes After Robotic Gait Training in Healthy Participants

Background. Recent studies have proposed a role for robotic gait training in participants with acquired brain injury, but the effects on the excitability of cortical and spinal neurons even in healthy participants are uncertain. Objective. To investigate changes in corticospinal excitability in healthy participants after active and passive robotic gait training in a driven gait orthosis (DGO), the Lokomat. Methods. Thirteen healthy participants took part in 2 experiments. Each participant performed 20 minutes of active and passive gait training in a DGO. Motor evoked potentials (MEP), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), F-wave frequency, and Mmax were measured in the right tibialis anterior muscle before and after training. Results. Active training led to a decline in MEP amplitude and F-wave frequency. The MEP decline was associated with subjective muscle fatigue. Passive training induced a decrease in SICI lasting for 20 minutes after training. Conclusions. The decline in MEP after active training is most likely because of central fatigue, whereas the decreased F-wave frequency might represent short-term plastic changes in the spinal cord. The decrease in SICI after passive training probably reflects a decrease in intracortical GABA activity, which could benefit the acquisition of new motor skills.