Operant Up-Conditioning of the Tibialis Anterior Motor-Evoked Potential in Multiple Sclerosis: Feasibility Case Studies

Figure 4

Changes in the TA MEP, MVC, and SP over the course of study and bilateral locomotor EMG in subjects B, C, and D. (a, b, c) Subject B. (a) Mean MEP size (filled triangle) and MVC (cross) in 6 baseline (shaded part of the panel) and 24 conditioning sessions. (b) Mean SP duration. (c) Rectified locomotor EMG activity in soleus and TA of both legs before (black) and after (red) conditioning. After successful MEP up-conditioning, locomotor EMG modulation increases in TA and soleus of both legs; not only the conditioned TA but also the soleus burst amplitude increased. (d, e) Subject C. (d) Mean MEP size and MVC in 6 baseline and 24 conditioning sessions. (e) Rectified locomotor EMG activity in soleus and TA bilaterally, before and after conditioning. After successful MEP up-conditioning, TA EMG burst amplitude increased in both legs. SP duration could not be measured in this subject. (f, g, h) Subject D. (f) Mean MEP size and MVC in 6 baseline and 24 conditioning sessions. (g) Mean SP duration. (h) Rectified locomotor EMG activity in soleus and TA bilaterally, before and after conditioning. In this subject, unlike subjects A–C, MEP up-conditioning had no significant effect.