Figure 6.

An off-response cannot explain the late neuronal modulation. A, Time course of responses evoked by a scramble stimulus with variable duration in a fixation task (i.e., a naive monkey was required to fixate without the report about the stimulus category), averaged over 227 pixels in the center of the chamber. Colors denote the stimulus duration time: blue, green, red, gray, and yellow correspond to 25, 40, 60, 80, and 100 ms, respectively. Line width denotes ±1 SEM over 15 trials. B, Time course of responses evoked by a 300 ms stimulus presentation in a face/scramble discrimination task, averaged over 172 and 181 pixels in two separate regions of interests (ROIs). Line width denotes ±1 SEM over five trials (carefully checked for eye movements); black bar, stimulus presentation. The blue ROI exhibits significant modulation (Wilcoxon rank-sum test between t = 100 and t = 170 ms poststimulus onset, p < 0.005 and between t = 170 and t = 200 ms poststimulus onset, p < 0.005).