Figure 3.

Analysis of response width. a, Examples of two typical patterns of spinal responses that present short (single peaks) or long (double peaks) responses. b, Distribution of response width computed for M1 (green bars) and PM (brown bars, plotted as a mirror reflection) based on significant spinal responses obtained at all stimulation amplitudes in M1 or PM sites (n = 153). A small but significant difference was found between M1 and PM responses (t test, p < 0.05) that reflects the tendency for PM-evoked responses to be shorter than M1-evoked responses. c, Average short (black line) and long (gray line) responses defined using a 4.5 ms criterion. Stimulation artifacts were first removed, and the single responses were then normalized to emphasize the response shape. Shaded areas around each average reflect the SEM. d, the dependency of response width on stimulation amplitude computed for M1 sites (green circles) and PM (brown triangles) sites. Correlation values (ρ) and their significance level are shown as well.