Visual-Spatial Agnosia Associated With Lesions of the Right Cerebral Hemisphere

McFie, John; Piercy, Malcolm; Zangwill, O. L.

doi:10.1093/brain/73.2.167

Cited by 277 publications

(74 citation statements)

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“…However, the majority of the studies have been concerned with mental arithmetic or other tasks that depend on interpreting conventional symbols for numbers (numerals or number words) for a review), while investigations into numerosity estimation are very sparse. Initially, neuropsychological studies showed that impairments in numerosity estimation are more likely to occur after right than left hemisphere damage (Kimura, 1996;McFie et al, 1950).…”

Section: Estimationmentioning

confidence: 99%

Exact and approximate judgements of visual and auditory numerosity: An fMRI study

Piazza

Mechelli

Price³

et al. 2006

Brain Research

199

161

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Human adults can assess the number of objects in a set (numerosity) by approximate estimation or by exact counting. There is evidence suggesting that numerosity estimation depends on a dedicated mechanism that is a-modal and non-verbal. By contrast, counting requires the coordination between the pre-existing numerosity estimation abilities with language and one-to-one correspondence principles. In this paper we investigate with fMRI the neural correlates of numerosity estimation and counting in human adults, using both visual and auditory stimuli. Results show that attending to approximate numerosity correlates with increased activity of a right lateralized fronto-parietal cortical network, and that this activity is independent of the stimuli presentation's modality. Counting activates additional left prefrontal, parietal, and bilateral premotor areas, again independently from stimulus modality. These results dissociate two neuronal systems that underlie different numerosity judgements. SECTION:Cognitive and Behavioural Neuroscience

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Section: Estimationmentioning

confidence: 99%

Exact and approximate judgements of visual and auditory numerosity: An fMRI study

Piazza

Mechelli

Price³

et al. 2006

Brain Research

199

161

View full text Add to dashboard Cite

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“…There has not been much clinical evidence that the parietal cortex is involved in the perception of surface orientation, except for the confusion of planes in drawings by patients with right parieto-occipital lesions (Paterson & Zangwill 1944;McFie et al 1950;Ettlinger et al 1957), for example, the frame of a bicycle was drawn in the frontal plane while the wheels were drawn in the sagittal plane. However, disturbances in the ability to draw 3D shapes such as houses (Piercy & de Ajuriaguerra 1960) or copy block designs (Critchley 1953) may be partly owing to a disturbance in the ability to perceive surface orientation.…”

Section: Surface-orientation Selective Neuronsmentioning

confidence: 99%

Neural coding of 3D features of objects for hand action in the parietal cortex of the monkey

Sakata

Taira

Kusunoki

et al. 1998

Phil. Trans. R. Soc. Lond. B

145

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In our previous studies of hand manipulation task-related neurons, we found many neurons of the parietal association cortex which responded to the sight of three-dimensional (3D) objects. Most of the task-related neurons in the AIP area (the lateral bank of the anterior intraparietal sulcus) were visually responsive and half of them responded to objects for manipulation. Most of these neurons were selective for the 3D features of the objects. More recently, we have found binocular visual neurons in the lateral bank of the caudal intraparietal sulcus (c-IPS area) that preferentially respond to a luminous bar or plate at a particular orientation in space. We studied the responses of axis-orientation selective (AOS) neurons and surfaceorientation selective (SOS) neurons in this area with stimuli presented on a 3D computer graphics display. The AOS neurons showed a stronger response to elongated stimuli and showed tuning to the orientation of the longitudinal axis. Many of them preferred a tilted stimulus in depth and appeared to be sensitive to orientation disparity and/or width disparity. The SOS neurons showed a stronger response to a £at than to an elongated stimulus and showed tuning to the 3D orientation of the surface. Their responses increased with the width or length of the stimulus. A considerable number of SOS neurons responded to a square in a random dot stereogram and were tuned to orientation in depth, suggesting their sensitivity to the gradient of disparity. We also found several SOS neurons that responded to a square with tilted or slanted contours, suggesting their sensitivity to orientation disparity and/or width disparity. Area c-IPS is likely to send visual signals of the 3D features of an object to area AIP for the visual guidance of hand actions.

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“…It has long been known that patients with parietal lesions, and in particular right-sided lesions, demonstrate problems with tasks requiring spatial analysis [34,61]. These difficulties include dealing with object changes both in the picture plane [13,24,47,54,55] and in the depth plane [38,55,63].…”

Section: Introductionmentioning

confidence: 99%

A particular difficulty in discriminating between mirror images

Davidoff

Warrington

2001

Neuropsychologia

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We investigated the selective impairment of mirror image discrimination in a patient with bilateral parieto-occipital lesions (FIM). We report a difficulty with the discrimination between mirror images more selective than has been previously reported (Turnbull OH, McCarthy RA. Failure to discriminate between mirror-image objects: a case of viewpoint-independent object recognition? Neurocase 1996;2:63). FIM was asked to judge, in five same/different experiments, whether pairs of simultaneously presented line drawings of objects were identical. FIM demonstrated only a minor impairment in discriminating between orientations in the picture plane but was at chance in making discrimination between mirror images. An experiment with normal observers established that our results were not due to differences in task difficulty. Two further experiments investigated the effects of rotation on the discrimination of letters and geometric shapes. FIM's impairment extended to geometric shapes but not to letters. These results would be consistent with the preservation of an abstract representation for object recognition that did not code the difference between mirror image views.

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Visual-Spatial Agnosia Associated With Lesions of the Right Cerebral Hemisphere

Cited by 277 publications

References 0 publications

Exact and approximate judgements of visual and auditory numerosity: An fMRI study

Exact and approximate judgements of visual and auditory numerosity: An fMRI study

Neural coding of 3D features of objects for hand action in the parietal cortex of the monkey

A particular difficulty in discriminating between mirror images

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