Rapid definition of objective electrophysiological face-selective responses by means of fast periodic visual stimulation
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1
University of Louvain, Belgium
The human brain detects a face in a visual scene in a fraction of a second. Face-selective responses of the human brain have been defined in space and time with various methods and criteria, typically by subtracting out responses to visual objects from face-evoked responses. Here we introduce an approach that uses the periodicity of visual input to define face-selective electrophysiological responses objectively, with high sensitivity and without subtraction of responses from two different conditions. We recorded high-density (128-channels) electroencephalogram (EEG) in 10 participants presented with four 60-second sequences of object stimuli in their natural background. Stimuli were presented at a fixed rate of 5.88 Hz, with faces appearing every 5 stimuli (i.e., 5.88 Hz/5 = 1.18 Hz; sequence structure: OOOOFOOOOF"¦). Objects were of variable categories, and faces varied substantially in size, viewpoint, expression, etc. Following Fourier transform of the EEG data, there was a large response at 5.88 Hz in the EEG spectrum over medial and bilateral occipital sites, corresponding to the base stimulation rate. In each individual participant and for each 60s stimulation sequence, a response at 1.18 Hz and its harmonics (2F=2.35 Hz, 3F=3.53 Hz"¦) was observed, with signal-to-noise ratios (SNR) between 2 and 5 (200%-500% of signal increase). This objective face-selective response was centered on right occipito-temporal sites for all harmonics. While the 5.88 Hz response was unchanged, these responses disappeared when faces were presented non-periodically in the exact same stimulation sequence, or when the whole periodic sequence was presented with phase-scrambled stimuli. These observations highlight the high diagnosticity of fast periodic visual stimulation to define objectively and rapidly face-selective responses in the human brain and open an avenue for identifying category-related responses using this approach.
Keywords:
face perception,
SSVEP,
Face detection,
Periodicity,
frequency-tagging
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Poster
Topic:
Sensation and Perception
Citation:
Rossion
B,
Torfs
K,
Retter
T and
Liu-Shuang
J
(2015). Rapid definition of objective electrophysiological face-selective responses by means of fast periodic visual stimulation.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00335
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Dr. Bruno Rossion, University of Louvain, Louvain-la-Neuve, Belgium, bruno.rossion@uclouvain.be