title: Incongruent object/context relationships in visual scenes: where are they processed in the brain?
abstract: Rapid object visual categorization in briefly flashed natural scenes is influenced by the surrounding context. The neural correlates underlying reduced categorization performance in response to incongruent object/context associations remain unclear and were investigated in the present study using fMRI. Participants were instructed to categorize objects in briefly presented scenes (exposure duration=100ms). Half of the scenes consisted of objects pasted in an expected (congruent) context, whereas for the other half, objects were embedded in incongruent contexts. Object categorization was more accurate and faster in congruent relative to incongruent scenes. Moreover, we found that the two types of scenes elicited different patterns of cerebral activation. In particular, the processing of incongruent scenes induced increased activations in the parahippocampal cortex, as well as in the right frontal cortex. This higher activity may indicate additional neural processing of the novel (non experienced) contextual associations that were inherent to the incongruent scenes. Moreover, our results suggest that the locus of object categorization impairment due to contextual incongruence is in the right anterior parahippocampal cortex. Indeed in this region activity was correlated with the reaction time increase observed with incongruent scenes. Representations for associations between objects and their usual context of appearance might be encoded in the right anterior parahippocampal cortex.
authors.affiliation: Université de Toulouse, UPS, Centre de Recherche Cerveau et Cognition, France; CNRS, CerCo, Toulouse, France. Electronic address: florence.remy@cerco.ups-tlse.fr.
authors.forename: Florence
authors.initials: F
authors.lastname: Rémy
authors.affiliation: Université de Toulouse, UPS, Centre de Recherche Cerveau et Cognition, France; CNRS, CerCo, Toulouse, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vayssière
authors.affiliation: Université Lille Nord de France, UDSL, Laboratoire Neurosciences Fonctionnelles et Pathologies, CHU Lille, F-59000 Lille, France; CNRS, F-59000 Lille, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Pins
authors.affiliation: Université Lille Nord de France, UDSL, Laboratoire Neurosciences Fonctionnelles et Pathologies, CHU Lille, F-59000 Lille, France; CNRS, F-59000 Lille, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Boucart
authors.affiliation: Université de Toulouse, UPS, Centre de Recherche Cerveau et Cognition, France; CNRS, CerCo, Toulouse, France.
authors.forename: Michèle
authors.initials: M
authors.lastname: Fabre-Thorpe
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020534:Parahippocampal Gyrus / Q000502:physiology; D010775:Photic Stimulation; D013028:Space Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Congruence; Contextual associations; Natural scenes; fMRI