Figure 3. Force tracings, filtered EMG, and spike trains from 6 SMUs (waveforms on right) from 1 representative trial of each direction in one subject. SMUs no. 1, 2, 3, and 4 were active during CL. SMUs no. 1 and 3 were active during CL-P and P. SMUs no. 5 and 6 were active during IL-P. None of these SMUs was active during IL.