Fig. 1: Experimental paradigm.

a Locations of the electrodes in the temporal lobe for four subjects obtained by co-registering a post-operative CT scan with a pre-operative MRI structural image. b Example electrocorticogram (ECoG) recordings from 20 example electrodes from subject S1. c, d Perceptual tasks. Subjects performed contrast detection and orientation discrimination tasks while maintaining their fixation at the center of a grey background display, marked with a cross visible throughout the session. During the contrast detection task, a low-contrast (5% above detection threshold) sine-wave grating was displayed for 200 ms and subjects responded within the next 2000 ms by pressing a key if they were able to detect it. During the orientation discrimination task, a high-contrast (75%) sine-wave grating (target stimulus) of fixed orientation (45°) was presented for 200 ms, and after a delay of 200 ms, a slightly rotated (5% above discrimination threshold) grating (test stimulus) was presented for 200 ms. Subjects responded within 2000 ms by pressing a key if they judged the two stimuli to be different. e Average perceptual performance of four subjects during the detection (64.38 ± 4.5%, mean ± SEM, n = 4 subjects) and discrimination (55.83 ± 4.7%, mean ± SEM, n = 4 subjects) tasks (f) Top: broad-band ECoG signal during one example trial corresponding to the detection and discrimination tasks from one example electrode. Shaded regions represent stimulus presentation. Bottom: spectrogram of the signal from the top panel. Stimulus presentation is marked by dashed-line rectangles.