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Mozer, M. C.; Halligan, Peter; Marshall, J. C. (1997)
Publisher: MIT Press
Languages: English
Types: Article
Subjects: RC0321, BF
For more than a century, it has been known that damage to\ud the right hemisphere of the brain can cause patients to be\ud unaware of the contralesional side of space. This condition,\ud known as unilateral neglect, represents a collection of clinically\ud related spatial disorders characterized by the failure in\ud free vision to respond, explore, or orient to stimuli predominantly\ud located on the side of space opposite the damaged\ud hemisphere. Recent studies using the simple task of line bisection,\ud a conventional diagnostic test, have proven surprisingly\ud revealing with respect to the spatial and attentional impairments\ud involved in neglect. In line bisection, the patient is asked\ud to mark the midpoint of a thin horizontal lie on a sheet of\ud paper. Neglect patients generally transect far to the right of the\ud center. Extensive studies of line bisection have been conducted,\ud manipulating-among other factors-line length, orientation,\ud and position. We have simulated the pattern of results\ud using an existing computational model of visual perception\ud and selective attention called MORSEL (Mozer, 1991). MORSEL has\ud already been used to model data in a related disorder, neglect\ud INTRODUCTION\ud Neglect\ud Unilateral neglect or bemi-inattention describes a collection\ud of behavioral symptoms in which patients appear\ud to ignore, forget, or turn away from contralesional space\ud (Heilman, Watson, & Valenstein, 1993). Neglect after\ud right-sided lesions is more frequent, long lasting, and\ud severe than after equivalent lesions of the left hemisphere.\ud The disorder can compromise visual, auditory,\ud tactile, and olfactory modalities and may involve personal,\ud peripersonal, extrapersonal, and “imaginal” space\ud (Halligan & Marshall, 1993a). Unilateral neglect is far\ud from a unitary phenomenon and has been shown to\ud fractionate into a number of dissociable components in\ud dyslexia (Mozer & Behrmann, 1990). In this earlier work, MORSEL\ud was “lesioned” in accordance with the damage we suppose to\ud have occurred in the brains of neglect patients. The same\ud model and lesion can simulate the detailed pattern of performance\ud on line bisection, including the following observations:\ud (1) no consistent across-subject bias is found in normals; (2)\ud transection displacements are proportional to line length in\ud neglect patients; (3) variability of displacements is proportional\ud to line length, in both normals and patients; (4) position of the\ud lines with respect to the body or the page on which they are\ud drawn has little effect; and (5) for lines drawn at different\ud orientations, displacements are proportional to the cosine of\ud the orientation angle. MORSEL fails to account for one observation:\ud across patients, the variability of displacements for a\ud particular line length is roughly proportional to mean displacement.\ud Nonetheless, the overall fit of the model is sufficiently\ud good that we believe MORSEL can be used as a diagnostic tool\ud to characterize the specific nature of a patient’s deficit, and\ud thereby has potential down the line in therapy.
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    • Axenfeld, D. (1915). Hemianopische Gesichtsfeldstroungen nach Schadelschussen.Klin.Monatsble.Angerbeilkd., 55, 126-143.
    • Barbieri,C., & De Renzi,E. (1989). Patterns of neglect dissociation. Bebavioural Neurology, 2, 13-24.
    • Behrmann,M., Moscovitch,M., Black, S. E., & Mozer, M. C. (1990). Perceptual and conceptual mechanisms in neglect dyslexia:?bvo contrasting case studies.Brain, 113, 1163- 1183.
    • Bisiach, E., Bulgarelli, C., Sterzi,R., & Vallar, G. (1983). Line bisection and cognitive plasticity of unilateral neglect of space. Brain and Cognition, 2, 32-38.
    • Bisiach, E., Capitani, E., Colombo,A., & Spinnler,H. (1976). Halving a horizontal segment:A study on hemispheredamaged patients with focal cerebral lesions.Archives Suisses de Neurologie, Neurocbirgurie et de Psycbiatrie, 118,199-206.
    • Bradshaw,J. L., Nettleton, N. C., Nathan, G., & Wilson, L. E. (1985). Bisecting rods and lines: Effects of horizontal and vertical posture on left side underestimation by normal subjects.Neuropsycbologia,23, 421-436.
    • Burnett-Stuart,G., Halligan, I? W., & Marshall,J. C. (1991). A Newtonian model of perceptual distortion in visuo-spatial neglect. NeuroReport, 2, 255-257.
    • Butter, C. M. (1987). Varieties of attention and disturbances of attention:A neuropsychological analysis. In M.Jeannerod (Ed.),Neuropbysiological and neuropsycbological aspects of spatial neglect (pp. 1-24). Amsterdam:North Holland.
    • Butter, C. M., Evans,J., Kirsch,N., & Kewans,D. (1989). Altitudinal neglect following traumatic brain injury: A case report. Cortex, 25, 135-146.
    • Halligan, I? W., Manning, L., & Marshall,J. C. (1991). Hemispheric activation versus spatio-motor cueing in visual neglect: A case study.Neuropsycbologia,29, 165-175.
    • Halligan, I? W., & Marshall,J. C. (1988). How long is a piece of string?A study of line bisection in a case of visual neglect. Cortex, 24, 321-328.
    • Halligan, I? W., & Marshall,J. C. (1989a). Laterality of motor response in visuo-spatial neglect: A case study.Neuropsycbologia, 27, 1301-1307.
    • Halligan, I? W., & Marshall,J. C. (1989b). Perceptuwueing and perceptuo-motor compatibility in visuospatial neglect: A single case study.Cognitive Neuropsycbology, 6, 423- 435.
    • Halligan, I? W., & Marshall,J. C. (1989~)L.ine bisection in visuospatial neglect: Disproof of a conjecture. Cortex, 25, 517- 522.
    • Halligan, I? W., & Marshall,J. C. (1991a). Left neglect for near but not far space in man. Nature, 350, 498-500.
    • Halligan, I? W., & Marshall,J. C. (1991b). Recovery and regres sion in visuo-spatial neglect: A case study of learning in line bisection. Brain Injuv,5, 23-31.
    • Halligan, I? W., & Marshall,J. C. (1993a). The history and clinical presentation of visual neglect. In I. H. Robertson & J. c. Marshall (Fits.), Unilateral neglect: Clinical and experimental studies. London: Erlbaum.
    • Halligan, I? W., & Marshall,J. C. (1993b). The bisection of horizontal and radial lines:A case study of normal controls and ten patients with left visuo-spatial neglect. International Journal of Neuroscience, 70, 149-169.
    • Heilman,K. M., Bowers, D., & Watson, R. T.(1984). Pseudoneglect in a patient with partial callosal disconnection. Brain, 107, 519-532.
    • Heilman,K. M., Watson, R. T., & Valenstein,E. (1993). Neglect and related disorders.In K. M. Heilman & E. Valenstein (Eds.),Clinical neuropsycbology 2nd ed. (pp. 279-336). New York: Oxford University Press.
    • Kinsbourne, M. (1993). Orientational bias model of unilateral neglect: Evidence from attentional gradients within hemispace. In I. H. Robertson & J. C. Marshall (Eds.), Unilateral neglect: Clinical and experimental studies. Hove,UK: Erlbaum.
    • Koch, C., & Ullman, S. (1985).Shifts in selective visual attention: towards the underlying neural circuitry. Human Neurobiolou, 4, 219-227.
    • LaBerge, D., & Brown, V (1989). Theory of attentional operations in shape identification. Psychological Review, 96, 101-124.
    • Manning, L., Halligan, F! W., & Marshall,J. C. (1990). Individual variation in line bisection: A study of normal subjects with application to the interpretation of visual neglect. Neuropsychologia, 28, 647-655.
    • Marshall,J. C., & Halligan,I? W. (1989). When right goes left: An investigation of line bisection in a case of visual neglect. Cortex, 25, 503-515.
    • Marshall,J. C., & Halligan, I? W. (1990a). Line bisection in a case of visual neglect: Psychophysical studies with implications for theory. Cognitive Neuropsycholou, 7, 107-130.
    • Marshall,J. C., & Halligan, F! W. (1990b).The psychophysics of visuo-spatial neglect: A new orientation. Medical Science Research, 18, 429-430.
    • McClelland,J. L.,& Rumelhart, D. E. (1981). A n interactive activation model of context effects in letter perception: Part I. An account of basic findings. Psychological Review, 88, 375-407.
    • Mesulam, M-M. (1985). Principles of behavioral neurology Philadelphia: E A. Davis.
    • Mozer, M. C. (1991). The perception of multiple objects: A connectionist approach. Cambridge, MA: MIT Press/ Bradford Books.
    • Mozer, M. C., & Behrmann, M. (1990). On the interaction of selective attention and lexical knowledge: A connectionist account of neglect dyslexia. Cognitive Neuroscience, 2, 96-123.
    • Nichelli, F?,Rinaldi, M., & Cubelli, R. (1989). Selective spatial attention and length representation in normal subjects and in patients with unilateral spatial neglect. Brain and Cognition, 9, 57.
    • Poppelreuter, W. (1917).Die Storungan der Niederan und hoheren Seheistungen durch Nerletzung des Okzipitalhirns. In Die Psychischen Schadigungen durch Kopfschuss in Kreige (1914/1916). Vol. 1. Leipzig:Voss.
    • Rapcsak, S. Z., Cimino, C. R., & Heilman, K. M. (1988). Altitudinal neglect. Neurolou, 38, 277-281.
    • Riddoch, M.J., & Humphreys, G. W. (1983).The effect of cueing on unilateral neglect. Neuropsychologia,21, 589-599.
    • Schenkenberg, T., Bradford,D. C., & Ajax, E. T. (1980). Line bisection and unilateral visual neglect in patients with neurological impairment. Neurolou, 31, 509-517.
    • Smolensky,F! (1986). Information processing in dynamical systems: Foundations of harmony theory. In D. E. Rumelhart & J. L. McClelland (Eds.), Parallel distributed processing: Explorations in the micmstructure of cognition.Volume I: Foundations (pp. 194-281). Cambridge, MA: MIT PressBradford Books.
    • Tegner, R.,& Levander, H. (1991). The influence of stimulus properties on visual neglect.Journal of Neurology, Neurosurgety, and Psychiatty, 54, 882-887.
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