Focal and global attention modulate the expression of visuo-spatial neglect: A case study

doi:10.1016/0028-3932(94)90065-5

Neuropsychologia

Volume 32, Issue 1, January 1994, Pages 13-21

https://doi.org/10.1016/0028-3932(94)90065-5 Get rights and content

Abstract

We report a case of severe left visuo-spatial neglect consequent upon right-hemisphere stroke. In Experiment 1, we show that while the patient bisects horizontal lines significantly to the right of true centre, he is extremely accurate in placing a mark at the centre of an equivalent outlined square, Experiment 2 confirms that the lateral and radial accuracy obtained in the latter (square) task cannot be predicted from the lateral and radial displacements found in horizontal and vertical (radial) line bisection; the experiment also shows that the individual horizontal lines of a square can be bisected significantly more accurately than the same lines presented individually. Experiment 3 shows that the crucial figural component requisite for the accurate estimation of lateral extent is a large vertical (radial) line in right space. The obtained figural modulation of neglect is consistent with a model in which a large, unitary stimulus in right space engages and enhances the lesioned right hemisphere's intrinsic capacity to deploy global attention.

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Cited by (43)

Allocentric neglect strongly associated with egocentric neglect
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Citation Excerpt :
This combination could explain why allocentric neglect is contingent on egocentric neglect, but egocentric neglect can be observed in isolation. By either account, we note that data from a wide range of modalities (including single cell recording) might provide a physiologically plausible method for a ‘zoom lens’ mechanism for neglect (Halligan & Marshall, 1993, 1994) – with posterior regions found to effectively tune their receptive fields based on both bottom up and top down attentional demands. A recent review by Beck and Kastner (2009) summarizes elegantly this hypothesis: “… directed attention can be described as causing a constriction of receptive fields (RFs) in V4 and TEO from 4° to 8° to about 2°, thereby presumably enhancing spatial resolution.
Following brain injury, many patients experience egocentric spatial neglect, where they fail to respond to stimuli on the contralesional side of their body. On the other hand, allocentric, object-based neglect refers to the symptom of ignoring the contralesional side of objects, regardless of the objects’ egocentric position. There is an established tradition for considering these two phenomena as both behaviorally and anatomically dissociable. However, several studies and some theoretical work have suggested that these rather reflect two aspects of a unitary underlying disorder. Furthermore, in a recent large study Yue et al. [Archives of Physical Medicine and Rehabilitation 93 (2012) 156] reported that acute allocentric neglect is only observed in cases where substantial egocentric neglect is also present. In a new sample of right hemisphere stroke patients, we attempted to control for potential confounds by using a novel continuous measure for allocentric neglect (in addition to a recently developed continuous measure for egocentric neglect). Our findings suggest a strong association between egocentric and allocentric neglect. Consistent with the work of Yue et al. (2012), we found allocentric behavioral deficits only in conjunction with egocentric deficits as well as a large corresponding overlap for the anatomical regions associated with egocentric and with allocentric neglect. We discuss how different anatomical and behavioral findings can be explained in a unified physiologically plausible framework, whereby allocentric and egocentric effects interact.
Adaptation to leftward-shifting prisms reduces the global processing bias of healthy individuals
2010, Neuropsychologia
When healthy individuals are presented with peripheral figures in which small letters are arranged to form a large letter, they are faster to identify the global- than the local-level information, and have difficulty ignoring global information when identifying the local level. The global reaction time (RT) advantage and global interference effect imply preferential processing of global-level information in the normal brain. This contrasts with the local processing bias demonstrated following lesions to the right temporo-parietal junction (TPJ), such as those that lead to hemispatial neglect (neglect). Recent research from our lab demonstrated that visuo-motor adaptation to rightward-shifting prisms, which ameliorates many leftward performance deficits of neglect patients, improved the local processing bias of patients with right TPJ lesions (Bultitude, Rafal, & List, 2009). Here we demonstrate that adaptation to leftward-shifting prisms, which can induce neglect-like performance in neurologically healthy individuals, also reduces the normal global processing bias. Forty-eight healthy participants were asked to identify the global or local forms of hierarchical figures before and after adaptation to leftward- or rightward-shifting prisms. Prior to prism adaptation, both groups had greater difficulty ignoring irrelevant global information when identifying the local level (global interference) compared to their ability to ignore irrelevant local-level information when identifying the global level (local interference). Participants who adapted to leftward-shifting prisms showed a significant reduction in global interference, but there was no change in the performance of the rightward-shifting Prism Group. These results show, for the first time, that in addition to previously demonstrated effects on lateralised attention, prism adaptation can influence non-lateralised spatial attention in healthy individuals.
Visual spatial neglect in multiple sclerosis
2006, Cortex
Neuropsychological dysfunction in multiple sclerosis (MS) patients is now a well-established clinical finding. We examined the entity of visual spatial neglect in demyelinating disease and its correlation to the functional and neuroradiological parameters. The phenomenon of visual spatial neglect was examined in 20 (5 male and 15 female) MS patients. Two different examination methods were used – the line bisection test and the random shape cancellation test. The results were compared with 20 aged matched control individuals. The correlation of the visual spatial neglects to neurological deficits and handicaps, using Kurtzke's Expanded Disability Status Scale (EDSS), as well as with the MRI's neuroradiological findings, was analyzed. A highly significant different result on the line bisection test for three various line lengths (p = .006, p < .0001, p < .001) with displacement towards the right side was found. In all the cancellation subtests, a significant difference in error rate was found in comparing patients to controls toward a higher one on the left side of the MS patients (p = .005, p < .002, p < .0001 and p = .02 in the left side subtest, and p = n.s. in the right side subtest). There was no significant correlation between the cancellation tests and bisection results and the EDSS scale data, as well as with the neuroradiological findings. The present results demonstrate the presence of visual spatial neglect among MS patients, even without the demonstration of a characteristic neuroanatomical lesion. The hypotheses for this finding are discussed with a stress on the possibility of disruption of multiple intrahemispheric connections, especially under the condition of asymmetry of dominance regarding spatial attention.
Impaired working memory for location but not for colour or shape in visual neglect: A comparison of parietal and non-parietal lesions
2004, Cortex
Patients with spatial neglect due to right hemisphere pathology may show ‘revisiting’ behaviour during visual search and cancellation tasks, such that previously encountered targets are treated as if they are new discoveries. Revisiting behaviour is particularly evident when no visible trace is left to inform patients that a particular target has already been detected (Husain et al., 2001; Wojciulik et al., 2001), implying that spatial working memory may be impaired in neglect. To test whether working memory for location is selectively impaired relative to memory for colour and shape, we compared performances of right hemisphere neglect patients with parietal (n = 4) and non-parietal (n = 4) lesions on a change detection task. Patients were presented with a matrix containing four objects in different positions, and required to detect a change in the location, colour or shape of one of the objects following presentation of a brief visual mask. Parietal patients were selectively impaired in detecting location changes, regardless of the horizontal position of the object in the matrix, relative to colour and shape changes. This deficit of spatial working memory was not apparent for neglect patients with lesions that spared the parietal cortex. We conclude that the human parietal cortex is crucially involved in the updating and maintenance of spatial representations across saccades, and that neglect arising from parietal damage causes impairment in these re-mapping mechanisms.
The effect of ipsilesional cues on line-bisection errors: The importance of predictive value
2004, Neuropsychologia
Patients with unilateral neglect were tested on a line-bisection task in which vertical lines were added to the ipsilesional or contralesional end. During some blocks, these vertical lines accurately predicted the horizontal length of the line, while on other blocks the vertical lines had little predictive value. We found that much of the improvement for ipsilesional vertical bars can be explained by their ability to predict the extent of the horizontal line. These results suggest that the predictive value of a ipsilesional cue is responsible for the reduction in line-bisection errors noted by Halligan and Marshall [Neuropsychologia 32 (1994) 13]. This effect of the predictive ipsilesional cue may work in combination with the expanded attentional effects posited by the ipsilesional contraction model that they proposed.
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Focal and global attention modulate the expression of visuo-spatial neglect: A case study

Abstract

Neuropsychologia

Cortex

Acta psychol.

Neuropsychologia

Neuropsychologia

Neuropsychologia

Die Gestaltwahrnehmungen

The use of fractal image statistics in the estimation of lateral spatial extent

Spatial Vision