Figure 7.

Effect of lateral limb pulling (Test 4). A, Leftward pulling of the left limb during MLR-evoked locomotion. Sequential positions (40 ms between frames) of the left foot during two step cycles are shown. The foot trajectories in two cycles are shown by thick lines in stance, and by thin lines in swing; black and red lines indicate the unperturbed and perturbed steps, respectively. The gray arrow shows the direction of treadmill motion. B, C, The effect of limb pulling that was applied continuously during 10 sequential steps (Pull). The lateral limb position in stance (black line) and its peak deviation in swing (red line) are shown. D, E, The lateral foot position (mean ± SE) during swing and stance in the steps before pulling (Before), during pulling (Pull), and after pulling (After). Data are presented for locomotion evoked by stimulation of the SC (B, D) and MLR (C, E). D, E, Before, Pull, After: n = 15, 36, 15, and n = 25, 28, 7, respectively. F–I, Effects of lateral pulling on EMGs of Add-L (F, G) and Glut-L (H, I); the EMGs were rectified and averaged over 10 steps. The EMGs (arbitrary units, AU) are presented with low amplification (F, H) and with high amplification (G, I). The EMG for unperturbed steps (Control) is superimposed on the EMG for perturbed steps (with lateral pulling, Pull). Tr and St phases of the step cycle are indicated.