Figure 1.

A: Session view. B: Session schedule. Six baseline sessions were followed by 30 conditioning sessions (in DC participants) or 30 control sessions (in NS participants) sessions, and then by two follow-up sessions. C: Composition of baseline, control, conditioning, and follow-up sessions. D: Visual feedback screens for control and conditioning trials. In all trials, the number of the current trial within its block is displayed. Background EMG panel is present, but the EMG feedback graph remains invisible throughout the trials. Thus, no information on the ongoing EMG activity is provided to the participant. In every other step, tibial nerve stimulation elicits the soleus H-reflex in the late swing phase of the step cycle. In control trials (top), the H-reflex panel is not shown. In conditioning trials (bottom), the shading in the H-reflex panel indicates the rewarded H-reflex range for down-conditioning. The dark horizontal line is the average H-reflex size of the baseline sessions, and the vertical bar is the H-reflex size for the most recent trial. If that H-reflex size falls in the shaded area, the bar is green and the trial is a success. If it exceeds the shaded area, the bar is red and the trial is a failure. The running success rate for the current block is also shown.