The relationships between disorders of visual perception and unilateral spatial neglect

Gainotti, Guido; Tiacci, Camillo

doi:10.1016/0028-3932(71)90010-8

Cited by 73 publications

(15 citation statements)

References 17 publications

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“…Spatial neglect has been interpreted (Gainotti and Tiacci 1971;Milner 1987) as resulting from a general distortion of the conscious representation of space. Bisiach et al (1998Bisiach et al ( , 1999Bisiach et al ( , 2002 proposed a representational framework, the space anisometry hypothesis, by which the representational medium is thought to be pathologically anisometric along the horizontal dimension: that is, it is progressively "relaxed" towards the contralesional space and progressively "compressed" towards the ipsilesional one in a logarithmic manner.…”

Section: Discussionmentioning

confidence: 99%

Reaction times and perceptual adjustments are sensitive to the illusory distortion of space

et al. 2012

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The Oppel-Kundt illusion (OKI) consists of the perception of a filled space as larger than an empty space of the same size. Here, we used a modified version of that illusion composed of a gradient of vertical lines whose spacing decreased progressively from one side to the other: space is expected to be perceived as larger where the lines are more compressed. We tested the hypothesis that a horizontal stimulus presented in a space perceived as larger will produce faster RTs by asking forty-four healthy subjects to respond as quickly as possible to lateralized stimuli (horizontal bars, vertical bars and circles) presented on different backgrounds (control condition: evenly spaced vertical lines or an empty space; illusory conditions: vertical lines progressively compressed to the right or the left). Subjects' RTs were reliably faster for horizontal stimuli presented on the space perceived as larger than on the space perceived as smaller. To verify that this effect was actually due to a size illusion, the same subjects were asked to adjust the size of the stimuli presented on the same backgrounds as to make them equal to a reference stimulus. For horizontal stimuli, subjects produced adjustments in accordance with the predicted effect of the illusion. Together, these data show that the OKI produces a distortion of space that extends to stimuli placed in front of it and that RTs are influenced by the perceived and not the physical size of the stimuli. Implications for neural bases of illusions and for spatial neglect are discussed.

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Section: Discussionmentioning

confidence: 99%

Reaction times and perceptual adjustments are sensitive to the illusory distortion of space

et al. 2012

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“…In addition to these symptoms, over the last decade, several authors have also reported evidence for a distortion of visual space in such patients [3,12,13,19,26,28], a phenomenon initially described by Gainotti and Tiacci in 1971 [9]. The patients perceive two identical horizontally arranged objects as different in size with the left object ap-pearing subjectively shorter than the right one.…”

Section: Introductionmentioning

confidence: 91%

Eye-movement patterns do not mediate size distortion effects in hemispatial neglect: looking without seeing

et al. 2003

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Over the last decade a range of studies have shown that some patients with hemispatial neglect subjectively underestimate the size of objects presented in their contralesional hemispace. Recently, it has been suggested that the effect is simply due to either hemianopia [Brain 124 (2001) 527], or the combination of neglect and hemianopia [Neurology 52 (1999[Neurology 52 ( ) 1845]. In the current study we asked right hemisphere lesioned patients with and without neglect and hemianopia as well as healthy controls to judge either two horizontal or vertical lines presented simultaneously in right and left hemispace and monitored their eye movements. Three out of the six patients showed the predicted size distortion effect for horizontal lines. We found no evidence that the effect was mediated by eye movements. The two neglect patients who showed the strongest left side underestimation showed symmetrical (left, right) scanning of the lines both in terms of number of fixations and fixation time, yet they still failed to judge the relative size veridically. In addition, we did not find strong evidence for a link with hemianopia. We therefore propose that the effect reflects a computational/representational failure of processing for horizontal extent.

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“…It can manifest as repetitive behaviors, fixations, revisitings, cancelling of targets, or elaboration on drawings in the ipsilesional hemispace [4,5]. While in general neglect is a defective or "negative" manifestation, perseveration is a productive or "positive" manifestation of spatial bias [6].…”

Section: Introductionmentioning

confidence: 99%

Disentangling the Neuroanatomical Correlates of Perseveration from Unilateral Spatial Neglect

Kleinman

DuBois

Newhart

et al. 2013

Behavioural Neurology

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Abstract. Perseverative behavior, manifest as re-cancelling or re-visiting targets, is distinct from spatial neglect. Perseveration is thought to reflect frontal or parietal lobe dysfunction, but the neuroanatomical correlates remain poorly defined and the interplay between neglect and perseveration is incompletely understood. We enrolled 87 consecutive patients with diffusion-weighted, perfusion-weighted imaging, and spatial neglect testing within 24 hours of right hemisphere ischemic stroke. The degrees of spatial neglect and perseveration were analyzed. Perseveration was apparent in 46% (40/87) of the patients; 28% (24/87) showed perseveration only; 18% (16/87) showed both perseveration and neglect; and 3% (3/87) showed neglect only. Perseverative behaviors occur in an inverted "U" shape: little neglect was associated with few perseverations; moderate neglect with high perseverations; and in severe neglect targets may not enter consciousness and perseverative responses decrease. Brodmann areas of dysfunction, and the caudate and putament, were assessed and volumetrically measured. In this study, the caudate and putamen were not associated with perseveration. After controlling for neglect, and volume of dysfunctional tissue, only Brodmann area 46 was associated with perseveration. Our results further support the notion that perseveration and neglect are distinct entities; while they often co-occur, acute dorsolateral prefrontal cortex ischemia is associated with perseveration specifically.

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The relationships between disorders of visual perception and unilateral spatial neglect

Cited by 73 publications

References 17 publications

Reaction times and perceptual adjustments are sensitive to the illusory distortion of space

Reaction times and perceptual adjustments are sensitive to the illusory distortion of space

Eye-movement patterns do not mediate size distortion effects in hemispatial neglect: looking without seeing

Disentangling the Neuroanatomical Correlates of Perseveration from Unilateral Spatial Neglect

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