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Corentin Jacques, Talia Retter, Bruno Rossion; The spatio-temporal signatures of category-selective responses to natural images as evidenced with fast periodic visual stimulation. Journal of Vision 2015;15(12):692. doi: https://doi.org/10.1167/15.12.692.
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© ARVO (1962-2015); The Authors (2016-present)
Humans are extremely rapid at categorizing visual inputs, an ability which relies on occipito-temporal brain processes. Functional neuroimaging studies have identified the spatial organization of neural responses in these regions to ecologically-relevant categories such as faces, bodyparts or houses. However, much less is known about the spatio-temporal dynamics of these category-selective responses at the system level of organization. Here we investigate this issue by recording scalp electroencephalogram (EEG) during fast periodic visual stimulation (FPVS) with natural images (Rossion et al., 2015). Eleven subjects viewed 60 seconds sequences of natural images of various object categories displayed at a base frequency of 6 Hz (6 images/second), in which images of either faces, bodyparts or houses appeared every 5 images (oddball frequency =6Hz/5 =1.2Hz). Category-selective oddball responses manifest at the 1.2Hz oddball frequency and harmonics (2.4Hz, 3.6Hz, etc.). While significant oddball responses were observed for all categories over occipito-temporal regions, responses were much stronger for faces than for limbs and houses. Further, scalp topography pattern analyses point to distinct neural sources across category-selective responses, with responses to faces, bodyparts and houses respectively maximal at ventral occipito-temporal, lateral occipito-temporal, and dorso-medial occipital channels. Time-domain analyses indicate that EEG responses are dissociable across categories at multiple spatio-temporal windows from around 110ms to 500ms post-stimulus onset, with faces eliciting up to five distinct selective responses. These observations go well beyond traditional face-selective EEG responses as identified using transient stimulus presentation (i.e., N170) by indicating that multiple ecologically-relevant categories generate unique spatio-temporal signatures over posterior scalp regions. Finally, these findings highlight the power of the FPVS approach to reveal the spatio-temporal signatures of high-level visual processing at the system level. Rossion, B., et al. (2015). Fast periodic presentation of natural images reveals a robust face-selective electrophysiological response in the human brain. Journal of Vision.
Meeting abstract presented at VSS 2015
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