title: An FMRI investigation of the cortical network underlying detection and categorization abilities in hemianopic patients.
abstract: The current study aims to investigate visual scene perception and its neuro-anatomical correlates for stimuli presented in the central visual field of patients with homonymous hemianopia, and thereby to assess the effect of a right or a left occipital lesion on brain reorganization. Fourteen healthy participants, three left brain damaged (LBD) patients with right homonymous hemianopia and five right brain damaged (RBD) patients with left homonymous hemianopia performed a visual detection task (i.e. "Is there an image on the screen?") and a categorization task (i.e. "Is it an image of a highway or a city?") during a block-designed functional magnetic resonance imaging recording session. Cerebral activity analyses of the posterior areas-the occipital lobe in particular-highlighted bi-hemispheric activation during the detection task but more lateralized, left occipital lobe activation during the categorization task in healthy participants. Conversely, in patients, the same network of activity was observed in both tasks. However, LBD patients showed a predominant activation in their right hemisphere (occipital lobe and posterior temporal areas) whereas RBD patients showed a more bilateral activation (in the occipital lobes). Overall, our preliminary findings suggest a specific pattern of cerebral activation depending on the task instruction in healthy participants and cerebral reorganization of the posterior areas following brain injury in hemianopic patients which could depend upon the side of the occipital lesion.
authors.affiliation: Laboratoire de Psychologie et NeuroCognition, UMR 5105 CNRS- UPMF, Grenoble, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Perez
authors.forename: Carole
authors.initials: C
authors.lastname: Peyrin
authors.forename: Céline
authors.initials: C
authors.lastname: Cavézian
authors.forename: Olivier
authors.initials: O
authors.lastname: Coubard
authors.forename: Florent
authors.initials: F
authors.lastname: Caetta
authors.forename: Noa
authors.initials: N
authors.lastname: Raz
authors.forename: Netta
authors.initials: N
authors.lastname: Levin
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Doucet
authors.forename: Frédéric
authors.initials: F
authors.lastname: Andersson
authors.forename: Michaël
authors.initials: M
authors.lastname: Obadia
authors.forename: Olivier
authors.initials: O
authors.lastname: Gout
authors.forename: Françoise
authors.initials: F
authors.lastname: Héran
authors.forename: Julien
authors.initials: J
authors.lastname: Savatovsky
authors.forename: Sylvie
authors.initials: S
authors.lastname: Chokron
mesh_terms: D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000150:complications; D001931:Brain Mapping; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000473:pathology* / Q000502:physiology*; D002543:Cerebral Hemorrhage / Q000150:complications; D007839:Functional Laterality / Q000502:physiology; D006423:Hemianopsia / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000033:anatomy & histology / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology