Figure 15.

Effect of reward on movement-related activity. A, Distribution of index values that describe the relative difference in activity for movements in the same direction that are made toward a target (rewarded movement) and back to the center (nonrewarded movement). Positive values indicate greater activity for rewarded movements. Each movement-related neuron contributes one index value. Index values for neurons with significant activity only for rewarded movements are shown in white. B, Distribution of index values that describe the relative difference for return movements that are not rewarded (no-stop signal trial return movements) and return movements that are rewarded (corrected trial return movements). Only reward-contingent movement cells are shown. Positive values indicate greater activity for rewarded movements. Cells with significant activity for return movements on corrected trials are shown in dark gray. C, Same index as shown in A for muscle activity. D, Same index as shown in B for muscle activity.