title: Contralesional cross-over in chronic neglect: visual search patterns reveal neglect of the ipsilesional hemispace.
abstract: BACKGROUND
  With neuropsychological rehabilitation approaches neglect patients can learn to compensate for the reduced awareness of the contralesional hemispace that is often observed after right brain damage. Here, we report contralesional "cross-over" deviations in line bisection that are hypothesized to be a result of focusing on the contralesional hemispace while the intact hemispace is "neglected". We investigate whether this unexpected pattern of deviation is related to defects in the visual field, motor intention/hypokinesia deficits or deficits in working memory.
  
  
  METHODS
  Neglect patients with and without homonymous field defects were screened for contralesional cross-over deviations in line bisection of long lines. During line bisection eye movements were recorded in two conditions with and without requiring hand movements in order to search for directional hypokinesia. Visual fields were tested with near-threshold perimetry and with supra-threshold campimetry.
  
  
  RESULTS
  Of 53 chronic neglect patients only 8 showed cross-over in line bisection. Evidence for directional hypokinesia was found in only one patient. Patients with cross-over focused more often to the left than to the right of the objective line midpoint. Patients with and without visual field defects did not differ in the extent of cross-over deviations. Cross-over deviation and inconsistent stimulus detection in left hemispace were correlated irrespective of the presence of a visual field deficit. Larger cross-over deviations were associated with poorer verbal working memory span, and disorganized patterns of eye movement were related to reduced visuo-spatial working memory capacity.
  
  
  CONCLUSIONS
  Increasing awareness of the disorder and the use of compensatory strategies may have led to a cross-over shift of visual search dominance towards the neglected side resulting in an exploration deficit of the ipsilesional side.
authors.affiliation: Otto-von-Guericke University of Magdeburg, Medical Faculty, Institute of Medical Psychology, Magdeburg, Germany. carolin.gall@med.ovgu.de
authors.forename: Carolin
authors.initials: C
authors.lastname: Gall
authors.forename: Tobias
authors.initials: T
authors.lastname: Günther
authors.forename: Franziska
authors.initials: F
authors.lastname: Fuhrmans
authors.forename: Bernhard A
authors.initials: BA
authors.lastname: Sabel
mesh_terms: D001288:Attention / Q000502:physiology*; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology*; D003430:Cross-Sectional Studies; D005133:Eye Movements / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000209:etiology; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000175:diagnosis / Q000503:physiopathology*; D010775:Photic Stimulation; D011597:Psychomotor Performance; D012720:Severity of Illness Index; D013028:Space Perception / Q000502:physiology; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed; D014706:Verbal Learning / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*