Left of what? The role of egocentric coordinates in neglect

OBJECTIVES Egocentric coordinate systems centred on the trunk, head, and gaze have been investigated in a patient who displays severe extrapersonal neglect and in five control subjects. METHODS The subjects were tested with a blind tactile exploration task in five different experimental conditions in which the role of the three distinct frames of reference was individually controlled. RESULTS Only the trunk centred coordinates significantly influenced the performance of the patient, therefore proving of paramount importance in determining the boundaries of the neglected field. Similar results emerged from a single word reading task, in which the patient’s performance improved when the stimuli were presented to the right of his body’s midline. CONCLUSION These findings point to the importance of the body centred coordinate system in determining the area of extrapersonal spatial neglect.

[1]  L. Gauthier,et al.  The Bells Test: A quantitative and qualitative test for visual neglect. , 1989 .

[2]  E. Renzi,et al.  Hemispheric contribution to exploration of space through the visual and tactile modality. , 1970, Cortex; a journal devoted to the study of the nervous system and behavior.

[3]  E. Làdavas,et al.  Is the hemispatial deficit produced by right parietal lobe damage associated with retinal or gravitational coordinates? , 1987, Brain : a journal of neurology.

[4]  R. Cubelli,et al.  Ignoring left and far: An investigation of tactile neglect , 1996, Neuropsychologia.

[5]  K M Heilman,et al.  Hemispatial visual inattention masquerading as hemianopia , 1989, Neurology.

[6]  J. Marshall,et al.  Lateral and radial neglect as a function of spatial position: A case study , 1995, Neuropsychologia.

[7]  Alfonso Caramazza,et al.  Theory and methodology in cognitive neuropsychology: A response to our critics , 1988 .

[8]  Is visual neglect body-centric? , 1995, Journal of neurology, neurosurgery, and psychiatry.

[9]  M. Jeannerod,et al.  [Egocentric reference and represented space]. , 1989, Revue neurologique.

[10]  J. Driver,et al.  Can Visual Neglect Operate in Object-centred Co-ordinates? An Affirmative Single-case Study , 1991 .

[11]  S. Folstein,et al.  "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. , 1975, Journal of psychiatric research.

[12]  H. Karnath,et al.  Trunk orientation as the determining factor of the 'contralateral' deficit in the neglect syndrome and as the physical anchor of the internal representation of body orientation in space. , 1991, Brain : a journal of neurology.

[13]  Morris Moscovitch,et al.  Object-Centered Neglect in Patients with Unilateral Neglect: Effects of Left-Right Coordinates of Objects , 1994, Journal of Cognitive Neuroscience.

[14]  K M Heilman,et al.  A comparison of the influences of body and environment centred reference frames on neglect. , 1994, Brain : a journal of neurology.

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

[16]  E. Renzi,et al.  The Occurrence of Visual Neglect in Patients With Unilateral Cerebral Disease , 1976, Cortex.

[17]  A. Young,et al.  Neglect and visual recognition. , 1992, Brain : a journal of neurology.

[18]  E. Bisiach,et al.  Two basic properties of space representation in the brain: evidence from unilateral neglect. , 1985, Journal of neurology, neurosurgery, and psychiatry.

[19]  L C Robertson,et al.  Covert orienting biases in scene-based reference frames: orientation priming and visual field differences. , 1995, Journal of experimental psychology. Human perception and performance.

[20]  Robin Walker,et al.  Spatial and object-based neglect , 1995 .

[21]  Alfonso Caramazza,et al.  Spatial representation of words in the brain implied by studies of a unilateral neglect patient , 1990, Nature.

[22]  Alfonso Caramazza,et al.  A framework for interpreting distinct patterns of hemispatial neglect , 1995 .

[23]  M. Albert A simple test of visual neglect , 1973, Neurology.

[24]  Martin Arguin,et al.  Evidence for an Independent Stimuluscentered Spatial Reference Frame from a Case of Visual Hemineglect , 1993, Cortex.

[25]  Reference frames for allocating attention to space-evidence from the neglect syndrome , 1989 .

[26]  E. Renzi,et al.  Constructional Apraxia and Hemispheric Locus of Lesion , 1964 .

[27]  Giuseppe Zappalà,et al.  The mini‐mental state examination: Normative study of an Italian random sample , 1993 .

[28]  H. Karnath Disturbed coordinate transformation in the neural representation of space as the crucial mechanism leading to neglect , 1994 .

[29]  M. Raichle,et al.  Localization of a human system for sustained attention by positron emission tomography , 1991, Nature.

[30]  A. Young,et al.  “Neglect dyslexia” and the early visual processing of letters in words and nonwords , 1987 .

[31]  A. Caramazza,et al.  The case for single-patient studies , 1988 .

[32]  D. Levine,et al.  Left visual spatial neglect is both environment‐centered and body‐centered , 1987, Neurology.

[33]  J. Raven Guide to using the Coloured Progressive Matrices. , 1958 .

[34]  Roberto Cubelli,et al.  Selective spatial attention and length representation in normal subjects and in patients with unilateral spatial neglect , 1989, Brain and Cognition.

[35]  M. Imbert,et al.  Variations of the egocentric reference among normal subjects and a patient with unilateral neglect , 1995, Neuropsychologia.

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

[37]  H Spinnler,et al.  A cancellation test: its reliability in assessing attentional deficits in Alzheimer's disease , 1992, Psychological Medicine.

[38]  Ian H. Robertson,et al.  Unilateral Neglect: Clinical and Experimental Studies edited by Ian H. Robertson and John C. Marshall , 1994 .

[39]  L. Diller,et al.  Hemi-inattention in rehabilitation: the evolution of a rational remediation program. , 1977, Advances in neurology.