title: Temporal components in the parahippocampal place area revealed by human intracerebral recordings.
abstract: Many high-level visual regions exhibit complex patterns of stimulus selectivity that make their responses difficult to explain in terms of a single cognitive mechanism. For example, the parahippocampal place area (PPA) responds maximally to environmental scenes during fMRI studies but also responds strongly to nonscene landmark objects, such as buildings, which have a quite different geometric structure. We hypothesized that PPA responses to scenes and buildings might be driven by different underlying mechanisms with different temporal profiles. To test this, we examined broadband γ (50-150 Hz) responses from human intracerebral electroencephalography recordings, a measure that is closely related to population spiking activity. We found that the PPA distinguished scene from nonscene stimuli in ∼80 ms, suggesting the operation of a bottom-up process that encodes scene-specific visual or geometric features. In contrast, the differential PPA response to buildings versus nonbuildings occurred later (∼170 ms) and may reflect a delayed processing of spatial or semantic features definable for both scenes and objects, perhaps incorporating signals from other cortical regions. Although the response preferences of high-level visual regions are usually interpreted in terms of the operation of a single cognitive mechanism, these results suggest that a more complex picture emerges when the dynamics of recognition are considered.
authors.affiliation: Fonctions Cérébrales et Neuromodulation, Université Joseph Fourier, 38042 Grenoble, France. julien.bastin@ujf-grenoble.fr
authors.forename: Julien
authors.initials: J
authors.lastname: Bastin
authors.forename: Juan R
authors.initials: JR
authors.lastname: Vidal
authors.forename: Seth
authors.initials: S
authors.lastname: Bouvier
authors.forename: Marcela
authors.initials: M
authors.lastname: Perrone-Bertolotti
authors.forename: Damien
authors.initials: D
authors.lastname: Bénis
authors.forename: Philippe
authors.initials: P
authors.lastname: Kahane
authors.forename: Olivier
authors.initials: O
authors.lastname: David
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Lachaux
authors.forename: Russell A
authors.initials: RA
authors.lastname: Epstein
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D020534:Parahippocampal Gyrus / Q000503:physiopathology*; D010775:Photic Stimulation; D021641:Recognition, Psychology / Q000502:physiology*; D013997:Time Factors; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult