Journal Article

The Relationship of Gamma Oscillations and Face-Specific ERPs Recorded Subdurally from Occipitotemporal Cortex

Andrew D. Engell and Gregory McCarthy

in Cerebral Cortex

Volume 21, issue 5, pages 1213-1221
Published in print May 2011 | ISSN: 1047-3211
Published online October 2010 | e-ISSN: 1460-2199 | DOI: https://dx.doi.org/10.1093/cercor/bhq206
The Relationship of Gamma Oscillations and Face-Specific ERPs Recorded Subdurally from Occipitotemporal Cortex

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The perception of faces evokes characteristic electrophysiological responses at discrete loci in human fusiform gyrus and adjacent ventral occipitotemporal cortical sites. Prominent among these responses are a surface-negative potential at ∼200-ms postonset (face-N200) and face-induced spectral perturbations in the gamma band (face-γERSP). The degree to which these responses represent activity in the same cortical loci and the degree to which they are influenced by the same perceptual and task variables are unknown. We evaluated this anatomical colocalization and functional correlation in 2 experiments in which the electrocorticogram was recorded from subdural electrodes in 51 participants. Experiment 1 investigated the category specificity of the γERSP and its colocalization with the face-N200. Experiment 2 examined differences in face-N200 and face-γERSP to face stimuli that varied in featural complexity. We found that γERSP is a category-specific phenomenon with separate, though overlapping, category sensitivities as the N200. Further, the presence of face-γERSP at an electrode site significantly predicted the presence and amplitude of face-N200 at that site. However, the converse was not true in that face-N200 was evoked by impoverished face stimuli that did not induce face-γERSP. These results demonstrate that these electrophysiological responses reflect separate components of the brain's face processing system.

Keywords: ECoG; ERP; face; gamma; vision

Journal Article.  6730 words.  Illustrated.

Subjects: Neuroscience

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