Figure 6.

Single unit action potentials could be discriminated and extracted from the potentials recorded from microwires in the microchannels. Action potentials with similar waveforms were identified in the microchannel recordings obtained during treadmill locomotion and extracted using a time-amplitude window discriminator routine. A. The timing of these potentials was used to characterize single unit potentials with spike triggered averaging. Time locked average responses to the firing of one unit (vertical dashed line), recorded 51 days after sciatic transection, are shown for tibialis anterior (TA) and Soleus (Sol) EMG activity, and all four microchannels (μCh1-4). Inset: Average (dark line) action potential and variance in waveform shape about this average (shaded area) for this TA motor unit. Scale bar = 10μV/1ms. B. The timing of activity of this single unit (Spike), microchannel 2 activity (μCh2), and tibialis anterior EMG activity (TA) are displayed for four consecutive step cycles while walking on a level treadmill. Activity was synchronized with video recordings of treadmill locomotion. Shaded time periods represent the swing phase and underlined time periods represent the stance phase of the step cycle. Inset: probability of firing of this TA motor unit during a step cycle, as determined from spike timing during 12 consecutive steps.