Uncovering the neural magnitude and spatio-temporal dynamics of natural image categorization in a fast visual stream. (October 2016)

• Record Type: Journal Article
• Authors: Retter, Talia L.; Rossion, Bruno
• Is Part Of: Neuropsychologia. Volume 91(2016)
• Page Start: 9
• Page End: 28
• Publication Date: 2016-10
• Subjects: Electroencephalography -- Face -- Humans -- Frequency tagging -- Visual evoked potentials; Neuropsychology -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Neuropsychologie -- Périodiques; Neuropsychology; Periodicals; Electronic journals; 616.8
• DOI: 10.1016/j.neuropsychologia.2016.07.028
• Languages: English
• ISSNs: 0028-3932

Abstract

Abstract: Perceptual categorization occurs rapidly under natural viewing conditions. Yet, the neural spatio-temporal dynamics of category-selective processes to single-glanced, natural (i.e., unsegmented) images in a rapidly changing presentation stream remain unknown. We presented human observers with natural images of objects at a fast periodic rate of 12.5 Hz, i.e., every 80 ms. Images of faces were inserted every 3, 5, 7, 9, or 11 stimuli, defining stimulus-onset-asynchronies (SOAs) between 240–880 ms, i.e., presentation frequencies ( F s) between 4.17–1.14 Hz. Robust face-selective responses were objectively identified and quantified at F and its harmonics (2 F, 3 F, etc.) for every condition in the electroencephalogram (EEG). The summed-harmonic face-selective response was significantly reduced by 25% at the lowest face SOA, i.e. 240 ms between two faces, but remained stable from 400 ms SOA onward. This high-level, right lateralized face-selective response emerged at about 100 ms post-stimulus onset and progressed spatially throughout four successive time-windows (i.e., P1-face, N1-face, P2-face, P3-face) from posterior to anterior occipito-temporal electrode sites. The total duration of a category-selective response to a briefly presented face stimulus in a rapid sequence of objects was estimated to be 420 ms. Uncovering the neural spatio-temporal dynamics of category-selectivity in a rapid stream of natural images goes well beyond previous evidence obtained from spatially and temporally isolated stimuli, opening an avenue for understanding human vision and its relationship to categorization behavior. Highlights: Magnitude of a face-selective response is about 4 µV from frequency-domain analysis. Onset of the face-selective response is about 100 ms post-stimulus presentation. Duration of this high-level face-selective response is about 420 ms. Spatial and temporal response progression across four successive time-windows. Empirical evidence for the summation of multi-harmonic frequency responses.