Beyond unilateral neglect.

When required to set the endpoints of an imaginary horizontal line of a given length on the basis of its midpoint printed on a sheet of paper, left neglect patients most frequently misplaced endpoints leftwards. Though giving rise to the very same disproportion usually found with these patients on canonical line bisection tasks, this behaviour cannot be accommodated by current explanations of unilateral neglect. When the task was executed during leftward optokinetic stimulation (OKS), a manoeuvre known temporarily to improve neglect symptoms, the disproportion increased instead of vanishing. We therefore suggest that unilateral neglect is a manifestation of a disorder primarily implying a horizontal anisometry of space representation and that manipulations such as OKS may remove neglect without normalizing the representational medium itself.

[1]  C. Galletti,et al.  Cortical mechanisms of visual space representation , 1993 .

[2]  J. Gerstmann.  PROBLEM OF IMPERCEPTION OF DISEASE AND OF IMPAIRED BODY TERRITORIES WITH ORGANIC LESIONS RELATION TO BODY SCHEME AND ITS DISORDERS , 1942 .

[3]  M. Jeannerod.  Neurophysiological and neuropsychological aspects of spatial neglect. , 1987 .

[4]  J. Marshall,et al.  Left in the dark: The neglect of theory , 1994 .

[5]  H. Karnath,et al.  Decrease of contralateral neglect by neck muscle vibration and spatial orientation of trunk midline. , 1993, Brain : a journal of neurology.

[6]  M. Posner,et al.  Neural systems control of spatial orienting. , 1982, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[7]  Glyn W. Humphreys,et al.  The effect of cueing on unilateral neglect , 1983, Neuropsychologia.

[8]  M. Jeannerod,et al.  The Directional Coding of Reaching Movements. A Visuomotor Conception of Spatial Neglect , 1987 .

[9]  Kenneth M. Heilman,et al.  Directional hypokinesia , 1985, Neurology.

[10]  V. Ramachandran.  Anosognosia in Parietal Lobe Syndrome , 1995, Consciousness and Cognition.

[11]  Edoardo Bisiach,et al.  Challenging current accounts of unilateral neglect , 1994, Neuropsychologia.

[12]  E. Bisiach,et al.  Unilateral Neglect of Representational Space , 1978, Cortex.

[13]  Ian H. Robertson,et al.  Spatio-motor cueing in unilateral left neglect: The role of hemispace, hand and motor activation , 1992, Neuropsychologia.

[14]  E. Bisiach,et al.  Remission of somatoparaphrenic delusion through vestibular stimulation , 1991, Neuropsychologia.

[15]  E. Bisiach,et al.  Remission of hemineglect and anosognosia during vestibular stimulation , 1987, Neuropsychologia.

[16]  M. Kinsbourne.  Mechanisms of Unilateral Neglect , 1987 .

[17]  J. Bradshaw,et al.  Horizontal visual motion modulates focal attention in left unilateral spatial neglect. , 1994, Journal of neurology, neurosurgery, and psychiatry.

[18]  E. Bisiach,et al.  Disorders of perceived auditory lateralization after lesions of the right hemisphere. , 1984, Brain : a journal of neurology.

[19]  A. Milner.  Animal Models for the Syndrome of Spatial Neglect , 1987 .

[20]  F. Doricchi,et al.  Amplitude and speed change of the optokinetic response in patients with and without neglect. , 1995, Neuroreport.

[21]  M. Perenin,et al.  Partial Remission of Hemiplegia and Somatoparaphrenia Through Vestibular Stimulation in a Case of Unilateral Neglect , 1992, Cortex.

[22]  Kenneth M. Heilman,et al.  Hemispace and Hemispatial Neglect , 1987 .

[23]  G. Antonucci,et al.  Effect of Optokinetic Stimulation in Patients with Visual Neglect , 1990, Cortex.

[24]  G. Rizzolatti,et al.  Space coding by premotor cortex , 2004, Experimental Brain Research.

[25]  M. Sugishita,et al.  Improvement of left unilateral spatial neglect in a line extension task , 1994, Neurology.

[26]  S. Ishiai,et al.  Preserved leftward movement in left unilateral spatial neglect due to frontal lesions. , 1994, Journal of neurology, neurosurgery, and psychiatry.

[27]  L. Pizzamiglio,et al.  The Wundt-Jastrow illusion in the study of spatial hemi-inattention , 1988, Neuropsychologia.

[28]  G. Vallar,et al.  Improvement of left visuo-spatial hemineglect by left-sided transcutaneous electrical stimulation , 1995, Neuropsychologia.

[29]  A. Rubens.  Caloric stimulation and unilateral visual neglect , 1985, Neurology.