Horizontal space misrepresentation in unilateral brain damageI. Visual and proprioceptive-motor influences in left unilateral neglect

Fabrizio Doricchi, Gaspare Galati, Lara DeLuca, Daniele Nico, Francesca D'Olimpio

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Pages (from-to)1107-1117
Number of pages11
JournalNeuropsychologia
Volume40
Issue number8
Publication statusPublished - 2002

Keywords

  • Anisometry
  • Hemianopia
  • Horizontal space
  • Neglect
  • Proprioceptive

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Neuropsychology and Physiological Psychology

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