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Right hemisphere subject electrodes, fMRI, and icEEG time-series.

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posted on 30.11.2017, 19:10 by Cihan Mehmet Kadipasaoglu, Christopher Richard Conner, Vatche George Baboyan, Matthew Rollo, Thomas Allyn Pieters, Nitin Tandon

(A) Cortical surface models and subdural electrodes are shown for the subjects with right hemispheric coverage in all three regions of interest. Highlighted electrodes (colored spheres) met all anatomical and functional criteria for early visual cortex (EVC, green), and face-selective inferior occipital gyrus (f-IOG, blue) and fusiform gyrus (f-FG, red). Subject-specific fMRI activations, also depicted on cortical surfaces (subjects 1–3), indicate higher responses to faces than non-faces (faces > animate, inanimate, and scramble; p <0.01). fMRI data provided one of three selection criteria used to identify face-selective electrodes (via co-localization). Subject 4 was unable to participate in fMRI recordings (dashed black boxes). fMRI activations depicted in this last case are derived from grouped analysis in 18 healthy volunteers, co-registered to the subject’s own cortical model using a surface-based normalization technique. (B) icEEG time-series representations of normalized (z-scored) mean broadband gamma power changes (BGA; 60–120 Hz; -50 to 700 ms after stimulus onset; stim. on at t = 0 ms), with respect to pre-stimulus baseline (-700 to -200 ms), for EVC, f-IOG, and f-FG electrodes identified in each subject. Time-series traces are color-coded to respective stimulus category–faces (orange) vs. animate (purple) vs. inanimate (cyan) vs. scramble (gray) stimuli. Shading denotes 1 SEM (across electrodes/region/subject; n value). Horizontal orange bars below each trace represent onset of BGA face-selectivity used in f-IOG and f-FG latency difference contrasts (face > non-face stimuli; q < 0.01, FDR corrected for time-points; computed using odd-trials). Subject 4 did not undergo icEEG recordings. Note: Line drawings of non-face stimuli (Figs 14) were adapted with permission from: Snodgrass J.G. and Vanderwart M. "A standardized set of 260 pictures: Norms for name agreement, image agreement, familiarity, and visual complexity.” Journal of Experimental Psychology: Human Learning and Memory, Vol 6(2), 1980, 174–215, APA. The official portrait of President Barack Obama by Pete Souza (Figs 14), obtained from the White House website (https://www.whitehouse.gov/sites/whitehouse.gov/files/images/Administration/People/president_official_portrait_hires.jpg), is licensed under CC BY 3.0 US (http://creativecommons.org/licenses/by/3.0/us/) as pursuant to White House copyright policy (https://www.whitehouse.gov/copyright/). Original images have been converted to gray-scale and overlaid with grid.

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