title: Mirrored and rotated stimuli are not the same: A neuropsychological and lesion mapping study.
abstract: Agnosia for mirrored stimuli is a rare clinical deficit. Only eight patients have been reported in the literature so far and little is known about the neural substrates of this agnosia. Using a previously developed experimental test designed to assess this agnosia, namely the Mirror and Orientation Agnosia Test (MOAT), as well as voxel-lesion symptom mapping (VLSM), we tested the hypothesis that focal brain-injured patients with right parietal damage would be impaired in the discrimination between the canonical view of a visual object and its mirrored and rotated images. Thirty-four consecutively recruited patients with a stroke involving the right or left parietal lobe have been included: twenty patients (59%) had a deficit on at least one of the six conditions of the MOAT, fourteen patients (41%) had a deficit on the mirror condition, twelve patients (35%) had a deficit on at least one the four rotated conditions and one had a truly selective agnosia for mirrored stimuli. A lesion analysis showed that discrimination of mirrored stimuli was correlated to the mesial part of the posterior superior temporal gyrus and the lateral part of the inferior parietal lobule, while discrimination of rotated stimuli was correlated to the lateral part of the posterior superior temporal gyrus and the mesial part of the inferior parietal lobule, with only a small overlap between the two. These data suggest that the right visual 'dorsal' pathway is essential for accurate perception of mirrored and rotated stimuli, with a selective cognitive process and anatomical network underlying our ability to discriminate between mirrored images, different from the process of discriminating between rotated images.
authors.affiliation: Department of Neurology, Rouen University Hospital, France. Electronic address: olivier.martinaud@chu-rouen.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Martinaud
authors.affiliation: Department of Neurology, Rouen University Hospital, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mirlink
authors.affiliation: Department of Neurology, Rouen University Hospital, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Bioux
authors.affiliation: Department of Neurology, Rouen University Hospital, France.
authors.forename: Evangéline
authors.initials: E
authors.lastname: Bliaux
authors.affiliation: Department of Neurology, Rouen University Hospital, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Champmartin
authors.affiliation: Department of Neurology, Rouen University Hospital, France.
authors.forename: Dorothée
authors.initials: D
authors.lastname: Pouliquen
authors.affiliation: Department of Neuroradiology, Rouen University Hospital, France.
authors.forename: Yohann
authors.initials: Y
authors.lastname: Cruypeninck
authors.affiliation: Department of Neurology, Rouen University Hospital, France; Inserm U1079, IFRMP, Faculty of Medicine and Pharmacy, Rouen, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Hannequin
authors.affiliation: Department of Neuroradiology, Rouen University Hospital, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gérardin
mesh_terms: D000328:Adult; D000377:Agnosia / Q000523:psychology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010465:Perception / Q000502:physiology; D020521:Stroke / Q000473:pathology / Q000503:physiopathology*
keywords: Agnosia for mirrored stimuli; Orientation agnosia; Parietal lesion; Stroke; VLSM