Figure 16.

Movement-related activity on noncanceled trials ends earlier than activity on no-stop signal trials. A, Movement-related activity from a single cell in the pre-SMA with activity on no-stop signal trials (black) and on noncanceled trials (green). Activity on noncanceled trials ends earlier than it does on the no-stop signal trials (100 ms difference for movements to the right). The mean time the stop signal is presented is indicated by the dotted line (44.5 ms before movement onset). The velocity trajectory for each trial is shown above plot of neural data (gray, no-stop signal trials; green, noncanceled trials) along with the mean trajectory (heavy lines). B, Combined normalized activity across pre-SMA neurons (top) and SMA neurons (bottom) for movements to the right and left showing that noncanceled trial activity ends earlier than no-stop signal trial activity across populations. The mean time the stop signal is presented is indicated by the dotted line (pre-SMA: 17.8 ms before movement onset right, 29.3 ms left; SMA: 16.6 ms right, 17.9 ms left). Mean velocity trajectories across days are shown above each plot of the neural data (black, no-stop signal trials; green, noncanceled trials). Movements in both directions are indicated with a positive deflection.