title: Horizontal space misrepresentation in unilateral brain damage. I. Visual and proprioceptive-motor influences in left unilateral neglect.
abstract: Patients with unilateral neglect can misperceive horizontal distances in the contralesional space as being shorter than equivalent ipsilesional ones. We evaluated the visual and motor-proprioceptive components of space misrepresentation through a distance reproduction task performed both with and without visual guidance. Four groups of right brain damaged patients (neglect with hemianopia (N+H+), neglect with inferior quandrantanopia (N+Q+), neglect without hemianopia (N+H-) and patients without neglect or hemianopia (N-H-)) and one group of healthy controls (C) performed the line bisection task and reproduced horizontal distances either by setting the endpoints or by doubling the length of a line in the contralesional or ipsilesional space. The doubling length task was administered in three different conditions: (a) visuomotor (the patient draws the line in free vision); (b) visual (by sight the patient guides the examiner drawing the line); (c) proprioceptive-motor (the patient is blindfolded and manually inspects and extends the horizontal distance subtended by the line). Compared to C and N-H- patients, only N+H+ patients exhibited a significant ipsilesional shift in line bisection. N+H+ patients showed the most severe contralesional-overextension/ipsilesional-underextension asymmetry in the endpoint, visuomotor and visual line extension task. In the proprioceptive-motor condition no asymmetry was found and N+H- showed greater overextension on both sides of space. In N+H-, brain damage was mainly centered in central-frontal cortex and basal ganglia. These findings re-emphasize the relevance of damage to visual retinotopically organized representations of space in the genesis of horizontal space misrepresentation of neglect patients and suggest the possible association of a non-lateralized defective processing of proprioceptive-motor information with unilateral neglect.
authors.affiliation: Centro Ricerche di Neuropsicologia, Fondazione Santa Lucia, IRCCS, Laboratorio Europeo di Neuroscienze dell'Azione (L.E.N.A.), Via Ardeatina, 306 00179 Rome, Italy. fabrizio.doricchi@uniroma1.it
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Doricchi
authors.forename: Gaspare
authors.initials: G
authors.lastname: Galati
authors.forename: Lara
authors.initials: L
authors.lastname: DeLuca
authors.forename: Daniele
authors.initials: D
authors.lastname: Nico
authors.forename: Francesca
authors.initials: F
authors.lastname: D'Olimpio
mesh_terms: D000328:Adult; D000368:Aged; D001288:Attention / Q000502:physiology; D001925:Brain Damage, Chronic / Q000175:diagnosis / Q000503:physiopathology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000503:physiopathology; D004215:Distance Perception / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D006423:Hemianopsia / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010468:Perceptual Disorders / Q000175:diagnosis / Q000503:physiopathology*; D011434:Proprioception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*