title: Pseudoneglect in line bisection judgement is associated with a modulation of right hemispheric spatial attention dominance in right-handers.
abstract: The objective of this study was to validate a line bisection judgement (LBJ) task for use in investigating the lateralized cerebral bases of spatial attention in a sample of 51 right-handed healthy participants. Using functional magnetic resonance imaging (fMRI), the participants performed a LBJ task that was compared to a visuomotor control task during which the participants made similar saccadic and motoric responses. Cerebral lateralization was determined using a voxel-based functional asymmetry analysis and a hemispheric functional lateralization index (HFLI) computed from fMRI contrast images. Behavioural attentional deviation biases were assessed during the LBJ task and a "paper and pencil" symbol cancellation task (SCT). Individual visuospatial skills were also evaluated. The results showed that both the LBJ and SCT tasks elicited leftward spatial biases in healthy subjects, although the biases were not correlated, which indicated their independence. Neuroimaging results showed that the LBJ task elicited a right hemispheric lateralization, with rightward asymmetries found in a large posterior occipito-parietal area, the posterior calcarine sulcus (V1p) and the temporo-occipital junction (TOJ) and in the inferior frontal gyrus, the anterior insula and the superior medial frontal gyrus. The comparison of the LBJ asymmetry map to the lesion map of neglect patients who suffer line bisection deviation demonstrated maximum overlap in a network that included the middle occipital gyrus (MOG), the TOJ, the anterior insula and the inferior frontal region, likely subtending spatial LBJ bias. Finally, the LBJ task-related cerebral lateralization was specifically correlated with the LBJ spatial bias but not with the SCT bias or with the visuospatial skills of the participants. Taken together, these results demonstrated that the LBJ task is adequate for investigating spatial lateralization in healthy subjects and is suitable for determining the factors underlying the variability of spatial cerebral lateralization.
authors.affiliation: Université de Bordeaux, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CEA, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France. Electronic address: laure.zago@u-bordeaux.fr.
authors.forename: Laure
authors.initials: L
authors.lastname: Zago
authors.affiliation: Université de Bordeaux, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CEA, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Petit
authors.affiliation: Université de Bordeaux, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CEA, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France.
authors.forename: Gael
authors.initials: G
authors.lastname: Jobard
authors.affiliation: Université de Bordeaux, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CEA, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Hay
authors.affiliation: Université de Bordeaux, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CEA, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Mazoyer
authors.affiliation: Université de Bordeaux, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CEA, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Tzourio-Mazoyer
authors.affiliation: Center of Neurology, Division of Neuropsychology, Hertie Institute of Clinical Brain Research, University of Tübingen, 72076 Tübingen, Germany.
authors.forename: Hans-Otto
authors.initials: HO
authors.lastname: Karnath
authors.affiliation: Université de Bordeaux, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France; CEA, Institut des Maladies Neurodégénératives, Groupe d'Imagerie Neurofonctionnelle, UMR 5293, F-33000 Bordeaux, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mellet
mesh_terms: D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D012438:Saccades / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology
keywords: FMRI; Hemispheric lateralization; Human; Line bisection; Pseudoneglect; Spatial attention; Spatial neglect