January 17, 2021

Dissociated face- and word-selective intracerebral responses in the human ventral occipito-temporal cortex

The extent to which faces and written words share neural circuitry in the human brain is actively debated. Here we compared face-selective and word-selective responses in a large group of patients (N = 37) implanted with intracerebral depth electrodes in the ventral occipito-temporal cortex (VOTC). Both face-selective (i.e., significantly different responses to faces vs. nonface visual objects) and word-selective (i.e., significantly different responses to words vs. pseudofonts) neural activity is isolated through frequency-tagging. Critically, this sensitive approach allows to objectively quantify category-selective neural responses and disentangle them from general visual responses. About 70% of significant contacts show either only face-selectivity or only word-selectivity, with the expected right and left hemispheric dominance, respectively. Spatial dissociations are also found within core regions of face and word processing, with a medio-lateral dissociation in the fusiform gyrus (FG) and surrounding sulci, while a postero-anterior dissociation is found in the inferior occipital gyrus (IOG). Only 30% of the significant contacts show both face- and word-selective responses. Critically, in these contacts, across the VOTC or in the FG and surrounding sulci, between-category selective-amplitudes (faces vs. words) showed no-to-weak correlations, despite strong correlations in both the within-category selective amplitudes (face-face, word-word) and the general visual responses to words and faces. Overall, we conclude that category-selectivity for faces and written words is largely dissociated in the human VOTC.

 bioRxiv Subject Collection: Neuroscience

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