Figure 3.

Soleus H-reflex modulation during assisted stepping before and after locomotor training in SCI. The unconditioned soleus H-reflex modulation before (dashed lines) and after (solid lines) 60 sessions of body weight-supported treadmill training (BWSTT) (a) and the conditioned soleus H-reflex by subthreshold TMS at the conditioning-test interval of 1 ms (b) are indicated as a function of the step cycle. The mean amplitude of the unconditioned and conditioned soleus H-reflexes evoked at each bin is expressed as a percentage of the maximal M-wave evoked 80 ms after the test H-reflex. TMS was delivered at 0.95 times MEP threshold for the soleus muscle at a conditioning-test interval of 1-ms. Unconditioned and conditioned soleus H-reflexes were accepted when the associated M-waves ranged from 4 to 8% of the maximal M-wave evoked at each bin. H-reflex values are not indicated for some of the bins after BWSTT because they were not accepted based on the M-wave amplitude as a percentage of the maximal M-wave, which is different from not being evocable as was the case for before BWSTT. The step cycle was divided into 16 equal time windows or bins. Stance phase duration is identified by the grey region. Bin 1 corresponds to heel strike. Bins 8, 9, and 16 correspond approximately to stance-to-swing transition, swing phase initiation, and swing-to-stance transition, respectively.