title: Early averted gaze processing in the right Fusiform Gyrus: An EEG source imaging study.
abstract: Humans are able to categorize face properties with impressively short latencies. Nevertheless, the latency at which gaze recognition occurs is still a matter of debate. Through spatio-temporal analysis of high-density event-related potentials (ERP), we investigated the brain activity underlying the ability to spontaneously and quickly process gaze. We presented neutral faces with direct and averted gaze in a matching picture paradigm, where subjects had to detect repetition of identical faces and gaze was implicitly manipulated. The results indicate that faces with averted gaze were better discriminated than faces with direct gaze, and evoked stronger P100 amplitudes localized to the right fusiform gyrus. In contrast, direct gaze induced stronger activation in the orbital frontal gyrus at this latency. Later in time, at the beginning of the N170 component, direct gaze induced changes in scalp topography with a stronger activation in the right medial temporal gyrus. The location of these differential activations of direct vs. averted gaze further support the view that faces with averted gaze are perceived as less rewarding than faces with direct gaze. We additionally found differential ERP responses between repeated and novel faces as early as 50ms, thereby replicating earlier studies of very fast detection of mnestic aspects of stimuli. Together, these results suggest an early dissociation between implicit gaze detection and explicit identity processing.
authors.affiliation: Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland. Electronic address: cristina.berchio@unige.ch.
authors.forename: Cristina
authors.initials: C
authors.lastname: Berchio
authors.affiliation: Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland.
authors.forename: Tonia A
authors.initials: TA
authors.lastname: Rihs
authors.affiliation: Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland; Department of Mental Health and Psychiatry, University Hospitals of Geneva, Switzerland.
authors.forename: Camille
authors.initials: C
authors.lastname: Piguet
authors.affiliation: Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland; Department of Mental Health and Psychiatry, University Hospitals of Geneva, Switzerland.
authors.forename: Alexandre G
authors.initials: AG
authors.lastname: Dayer
authors.affiliation: Department of Mental Health and Psychiatry, University Hospitals of Geneva, Switzerland.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Aubry
authors.affiliation: Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland; Center for Biomedical Imaging (CIBM), Lausanne and Geneva, Switzerland.
authors.forename: Christoph M
authors.initials: CM
authors.lastname: Michel
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005149:Facial Expression; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology*; D055815:Young Adult
keywords: EEG source imaging; Evoked potentials; Face memory; Gaze processing; Topographic EEG analyses