title: Functional selectivity in the human occipitotemporal cortex during natural vision: evidence from combined intracranial EEG and eye-tracking.
abstract: Eye movements are a constant and essential component of natural vision, yet, most of our knowledge about the human visual system comes from experiments that restrict them. This experimental constraint is mostly in place to control visual stimuli presentation and to avoid artifacts in non-invasive measures of brain activity, however, this limitation can be overcome with intracranial EEG (iEEG) recorded from epilepsy patients. Moreover, the high-frequency components of the iEEG signal (between about 50 and 150Hz) can provide a proxy of population-level spiking activity in any cortical area during free-viewing. We combined iEEG with high precision eye-tracking to study fine temporal dynamics and functional specificity in the fusiform face (FFA) and visual word form area (VWFA) while patients inspected natural pictures containing faces and text. We defined the first local measure of visual (electrophysiological) responsiveness adapted to free-viewing in humans: amplitude modulations in the high-frequency activity range (50-150Hz) following fixations (fixation-related high-frequency response). We showed that despite the large size of receptive fields in the ventral occipito-temporal cortex, neural activity during natural vision of realistic cluttered scenes is mostly dependent upon the category of the foveated stimulus - suggesting that category-specificity is preserved during free-viewing and that attention mechanisms might filter out the influence of objects surrounding the fovea.
authors.affiliation: Lyon Neuroscience Research Center, Brain Dynamics and Cognition Team, INSERM U1028, CNRS UMR5292, Lyon, France; University Lyon 1, Lyon, France; Laboratoire de Psychologie Cognitive, CNRS UMR6146, Aix-Marseille Université, Marseille, France. Electronic address: carlos-miguel.hamame@univ-amu.fr.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Hamamé
authors.affiliation: Lyon Neuroscience Research Center, Brain Dynamics and Cognition Team, INSERM U1028, CNRS UMR5292, Lyon, France; University Lyon 1, Lyon, France.
authors.forename: Juan R
authors.initials: JR
authors.lastname: Vidal
authors.affiliation: University Grenoble Alpes, LPNC, Grenoble, France; CNRS, LPNC, UMR 5105, Grenoble, France.
authors.forename: Marcela
authors.initials: M
authors.lastname: Perrone-Bertolotti
authors.affiliation: Departamento de Psiquiatría, Facultad de Medicina y CIN, P. Universidad Católica de Chile, Santiago, Chile.
authors.forename: Tomas
authors.initials: T
authors.lastname: Ossandón
authors.affiliation: Lyon Neuroscience Research Center, Brain Dynamics and Cognition Team, INSERM U1028, CNRS UMR5292, Lyon, France; University Lyon 1, Lyon, France.
authors.forename: Karim
authors.initials: K
authors.lastname: Jerbi
authors.affiliation: Neurology Department, Grenoble University Hospital, Grenoble, France; INSERM U836, Grenoble Neuroscience Institute, Grenoble, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Kahane
authors.affiliation: Lyon Neuroscience Research Center, Brain Dynamics and Cognition Team, INSERM U1028, CNRS UMR5292, Lyon, France; University Lyon 1, Lyon, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bertrand
authors.affiliation: Lyon Neuroscience Research Center, Brain Dynamics and Cognition Team, INSERM U1028, CNRS UMR5292, Lyon, France; University Lyon 1, Lyon, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Lachaux
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D012815:Signal Processing, Computer-Assisted; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
keywords: Eye movements; Fusiform face area; High frequency gamma activity; Intracranial EEG; Natural vision; Visual word form area