Mechanisms of unilateral spatial neglect in copying a single object

Ishiai, Sumio; Seki, Kazuhiko; Koyama, Yasumasa; Yokota, Tsukasa

doi:10.1016/0028-3932(96)00017-6

Cited by 21 publications

(13 citation statements)

References 35 publications

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“…(Note that further exploration may be guided by cognitive exploration strategies based on higher-level memory of the number of items initially evaluated in the visual scene; cf below). Existence of such attentional 'zoom lens' correlated with loss of awareness in neglect patients is strongly suggested by the findings of Ishiai et al [11]; see also Refs. [10,94,124].…”

Section: General Restatement Of the Model And Predictionsmentioning

confidence: 84%

“…Why do patients fail to detect all the targets in a visual cancellation test, apparently unaware of their contralesional omissions, when they are able to correctly tick the four corners of the testing sheet beforehand [10]? Why do they copy only half a daisy or a house, apparently unaware that they have not completed their drawing, when they retain knowledge of all their components [11]? Why do they report only the ipsilesional side of well-known scenes from mental (visual) imagery [12,13]?…”

Section: Introductionmentioning

confidence: 99%

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The contribution of spatial remapping impairments to unilateral visual neglect

Pisella

Mattingley

2004

Neuroscience & Biobehavioral Reviews

133

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Section: General Restatement Of the Model And Predictionsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

The contribution of spatial remapping impairments to unilateral visual neglect

Pisella

Mattingley

2004

Neuroscience & Biobehavioral Reviews

133

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“…When copying, neglect patients typically draw the right side of the scene without noticing the incompleteness of the left side [73]. Because unilateral spatial neglect is observed under conditions where movements of the eyes and head are permitted, early accounts assumed that the term 'left' referred to left of the patient's midline.…”

Section: Different Frames Of Referencementioning

confidence: 99%

Spatial cognition: evidence from visual neglect

Halligan

Fink

Marshall

et al. 2003

Trends in Cognitive Sciences

502

274

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Recent work on human attention and representational systems has benefited from a growing interplay between research on normal attention and neuropsychological disorders such as visual neglect. Research over the past 30 years has convincingly shown that, far from being a unitary condition, neglect is a protean disorder whose symptoms can selectively affect different sensory modalities, cognitive processes, spatial domains and coordinate systems. These clinical findings, together with those of functional neuroimaging, have increased knowledge about the anatomical and functional architecture of normal subsystems involved in spatial cognition. We provide a selective overview of how recent investigations of visual neglect are beginning to elucidate the underlying structure of spatial processes and mental representations.Once considered a unitary syndrome, it is now accepted that visuospatial neglect results from the interplay of damage to several different cognitive processes [1,2]. Even within such relatively simple tasks as copying or spontaneous drawing, patients show many qualitatively distinct patterns of omission and distortion in 'left' space [3].Deficits of attention, intention, global-local processing, spatial memory and mental representation can all contribute to the clinical picture of neglect, which accordingly cannot be traced back to the disruption of a single supramodal process [1,4]. Many of the symptoms traditionally ascribed to left neglect share little in common other than a contra-lesional gradient of increasing impairment, with comparatively well -preserved performance on the ipsilesional (right) side of space [1,5].Although characterising and remediating the clinical condition [1,2,5] are clearly crucial, the primary interest for cognitive neuroscience is how conditions such as visual neglect can inform existing cognitive theory and functional anatomy. That an abnormal bias towards one side of space can exist in the absence of contralateral peripheral sensory or motor loss (e.g. visual field losses or hemi-paralysis) suggests that impairment to higher level processes must be involved. The standard approach taken by cognitive neuropsychology characterises complex mental processes as information-processing systems with separate but interconnected components. Some of the informationprocessing stages involved in visual object recognition (see Fig. 1) illustrate the potential levels and links where lateralised deficits can arise after brain damage.This model charts the processing routes from preattentive assignment of simple structural features (i.e. without the need for focused attention and conscious awareness) to post-attentional integration of local and global processing (involving selective attention and conscious awareness) and the assignment of relevant spatial frames of reference prior to recognition and naming.

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“…Marshall and Halligan's patient [33] always chose the nonburning house, not the house with red flames coming out from its left window, although she overtly noticed no difference between the two houses. In Ishiai et al's study [26], nearly 80 % of neglect patients were able to discriminate between the presence and the absence of the left-side petals when presented with a drawing of a daisy, although they always demonstrated apparent left neglect in copying. Bisiach and Rusconi's study [7] suggested that some patients with neglect may process the left-side figure contour and the size of stimuli.…”

Section: Introductionmentioning

confidence: 96%

“…Some studies report fair processing of some aspects of the left-side stimuli in neglect patients [26,33]. Marshall and Halligan's patient [33] always chose the nonburning house, not the house with red flames coming out from its left window, although she overtly noticed no difference between the two houses.…”

Section: Introductionmentioning

confidence: 96%

How do patients with neglect see a horizontal line?

et al. 2004

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Twelve patients with left unilateral spatial neglect were examined with a newly devised "coloured line bisection task". They were presented with a horizontal line printed in blue on one side and in red on the other side; the proportions of the blue and red segments were varied. Immediately after placement of the subjective midpoint, the line was concealed and the patients were asked to name the colours of the right and left ends. Five patients who identified the left-end colour almost correctly had no visual field defect, while the other seven whose colour naming was impaired on the left side had left visual field defect. The rightward bisection errors were similarly distributed in the fair and poor colour-naming patients except for two patients from the latter group. The lesions of the fair colour-naming patients spared the lingual and fusiform gyri, which are known to be engaged in colour processing. Patients with neglect whose visual field is preserved may neglect the leftward extension of a line but not the colour in the neglected space. The poor colour-naming patients frequently failed to name the left-end colour that appeared to the left of their subjective midpoint, which indicates that they hardly searched leftward beyond that point. In such trials, they reported that the left end had the same colour as the right end. The results suggest that in patients with neglect and left visual field defect, both the leftward extent and the colour of a line may be represented on the basis of the information from the attended right segment.

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Mechanisms of unilateral spatial neglect in copying a single object

Cited by 21 publications

References 35 publications

The contribution of spatial remapping impairments to unilateral visual neglect

The contribution of spatial remapping impairments to unilateral visual neglect

Spatial cognition: evidence from visual neglect

How do patients with neglect see a horizontal line?

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