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N Beschin

Publications and source records attributed to N Beschin.

11 recordsLinked to original sources
PubMed2000

Improving the clinical diagnosis of personal neglect: a reformulated comb and razor test.

Beschin and Robertson (1997) devised a simple clinical test of left personal neglect, which characterises personal grooming behaviour according to the proportion of the total activity that is directed to the left side of the body. Although this test proved highly reliable, and more sensitive than prior diagnostic techniques, its formulation may yet be improved. The present paper reports a reanalysis of Beschin and Robertson's (1997) data, using additional control subjects, and a formula which characterises personal neglect as a lateral bias of behaviour rather than as a lateralised deficit. It is shown that this formula greatly enhances the test's sensitivity to the behavioural abnormalities of brain damaged patients, and it is recommended that this modification be adopted for the future diagnosis of personal neglect.

Aged↗
PubMed2000

Perceiving left and imagining right: dissociation in neglect.

Signor Piazza, a patient with a left parieto-occipital haemorrhage and a right thalamic stroke, showed severe right personal neglect (e.g. touching own body parts) and right perceptual neglect in tasks with (e.g. cancelling tasks) or without (e.g. description of a complex picture) motor response. He had also right-sided neglect dyslexia (including single words), without language impairments. However, the patient also presented with a clear left-sided deficit in the representational domain (e.g. imagery tasks). Signor Piazza's pattern of performance suggests dissociation between imagery and perception within the neglect syndrome.

Aged↗
PubMed1999

Neglect without extinction.

A patient, AB, is reported who showed clear signs of neglect but no extinction (N+ E-). Several hypotheses proposed to account for this dissociation were put to the test. The postulated association between motor neglect and extinction did not hold good, nor did the possibility that the N+ E- dissociation may be traced back to the difference in test requirements and therefore observed only in patients with object-centred neglect. Likewise, manipulating the physical features of the stimuli (relative size, exposure time, presentation synchrony) did not elicit extinction. However, when the task demands were modified by asking the patient to perform a further spatial analysis of the stimuli, rather than simply detect them, extinction emerged. Since AB performed well on several neglect tasks requiring parallel processing, while failing all tasks calling for serial processing, the hypothesis is put forward that AB's N+ E- dissociation could be interpreted within the parallel/serial distinction framework.

Aged↗
PubMed1997

Personal versus extrapersonal neglect: a group study of their dissociation using a reliable clinical test.

The validation of a simple quantitative clinical test of personal neglect is described in this study of 17 right brain damaged CVA patients with extrapersonal neglect, 14 without unilateral extrapersonal neglect, 13 left brain damaged CVA patients and 17 age-matched controls. The test had a high reliability and clearly differentiated neglect patients from all other groups. Furthermore the test identified a much higher incidence of personal neglect among extrapersonal neglect patients (59%) than has previously been found. Moreover this study confirms earlier findings by showing a double dissociation between personal and extrapersonal neglect. Seven patients with extrapersonal neglect showed no personal neglect while five patients showing no extrapersonal neglect did show personal neglect on this test.

Activities of Daily Living↗
PubMed1997

What the eyes perceive, the brain ignores: a case of pure unilateral representational neglect.

Bisiach and Luzzatti (1978) provided evidence that unilateral spatial neglect is not only a disorder of visual perception, but also can affect mental representations such that patients fail to report the left side of scenes or objects in mental imagery. However in case reports of representational neglect generally it is accompanied by perceptual neglect. We report a rare occurrence of a patient (NL) who presents a persistent unilateral neglect which appears to be limited to visual imagery. The deficit appeared in tasks which require the formation and manipulation of new visuo-spatial representations as well as those which require access to information about familiar scenes. The patient, who had a lesion in the right parietal lobe, showed no evidence of perceptual or personal neglect, although there was some evidence of visual extinction. We argue that the concept of visuo-spatial working memory can provide a framework within which to interpret aspects of the representational form of neglect, whether or not it is accompanied by perceptual neglect.

Aged↗
PubMed1997

Agnosia for object orientation: implications for theories of object recognition.

Instances in which objects are copied accurately, but are dramatically rotated relative to the original, have been interpreted as evidence for viewpoint-independent accounts of the object recognition process. In two case reports, we demonstrate that patients who show rotation in copying also show difficulties in informing the examiner of the canonical orientation of known objects. In copying rotated versions of familiar objects, one subject showed a tendency to copy them in their canonical upright orientation, and both subjects copied non-representational line drawings with their principal axis vertically aligned, and with the irregular end pointing 'upwards'.

Aged↗
PubMed1997

Attentional competition between modalities: extinction between touch and vision after right hemisphere damage.

The phenomenon of extinction, which occurs frequently after unilateral brain damage, involves a failure to detect the more contralesional of two simultaneously presented stimuli, but with preserved detection of single ipsilesional or contralesional stimuli. Current accounts suggest that the disorder reflects a bias of selective attention, in which ipsilesional stimuli have a competitive advantage. Extinction may be manifested within any one of the major sensory modalities (vision, audition, touch), or it may occur within several modalities in a given individual. Given recent evidence in normals for attentional links between separate sensory modalities, we examined whether extinction can also occur cross-modally, i.e. for double-simultaneous stimuli in separate sensory modalities. We tested whether an ipsilesional event sufficient to extinguish a contralesional stimulus within the same modality may also extinguish a contralesional stimulus in a different modality. Our three patients had right hemisphere damage, and reliable within-modality extinction for visual and tactile stimuli. They also showed significant cross-modal extinction, such that an ipsilesional tactile (or visual) event extinguished awareness of a simultaneous visual (or tactile) event on the contralesional side. These results, which provide the first quantitative evidence for cross-modal extinction, were replicated in a second experiment in which visual and tactile stimuli in the cross-modal conditions were presented at non-homologous elevations within each hemispace. We conclude that after unilateral damage, ipsilesional stimuli have a competitive advantage over contralesional stimuli, and that this affects competition between stimuli from different modalities as well as stimuli within the same modality. These findings are consistent with recent evidence for competitive interactions between tactile and visual events in the control of spatial attention in normals.

Adult↗
PubMed1997

Auditory sustained attention is a marker of unilateral spatial neglect.

The relationships between performance on a non-spatially-lateralized measure of sustained attention and spatial bias on tests sensitive to unilateral neglect were considered in a group of 44 patients with right hemisphere lesions following stroke. As predicted from earlier studies showing a strong association between unilateral spatial neglect and sustained attention, performance on a brief and monotonous tone-counting measure formed a significant predictor of spatial bias across a variety of measures of unilateral visual neglect. This study provides further evidence for a very close link between two attentional systems hitherto regarded as being quite separate, namely a spatial attention system implicated in unilateral neglect and a sustained attention system. A close connection between these two systems was predicted by Posner, who argued that the right hemisphere-dominant sustained attention system provides a strong modulatory influence on the functioning of the lateralized posterior attention system.

Acoustic Stimulation↗
PubMed1997

Left of what? The role of egocentric coordinates in neglect.

OBJECTIVES: Egocentric coordinate systems centred on the trunk, head, and gaze have been investigated in a patient who displays severe extrapersonal neglect and in five control subjects. METHODS: The subjects were tested with a blind tactile exploration task in five different experimental conditions in which the role of the three distinct frames of reference was individually controlled. RESULTS: Only the trunk centred coordinates significantly influenced the performance of the patient, therefore proving of paramount importance in determining the boundaries of the neglected field. Similar results emerged from a single word reading task, in which the patient's performance improved when the stimuli were presented to the right of his body's midline. CONCLUSION: These findings point to the importance of the body centred coordinate system in determining the area of extrapersonal spatial neglect.

Aged↗
PubMed1996

Ignoring left and far: an investigation of tactile neglect.

The aims of this paper were to identify patients with tactile neglect, to corroborate its independence from visual neglect, to ascertain its presence along the radial dimension of space and to detect a gradient of performance, as recently reported for visual neglect. To this end eight patients with vascular right cerebral lesions and 28 healthy controls have been tested with a modified version of the tactile maze test of De Renzi et al. [Cortex, vol. 6, pp. 191-203, 1970] and a seven-test clinical battery to detect the presence of visual USN. Four patients presenting tactile USN were selected: two showed left tactile neglect while the other two showed tactile neglect for far space. The distribution of omissions showed a clear spatial gradient. Since our patients were blindfolded, neglect behaviour in the tactile domain cannot be attributed to the attractive power of visual information. However, 25% of the normal subjects were also significantly faster in the 'near' space pointing towards the possibility that neglect for 'far' space can reflect the exaggeration of a normal asymmetry.

Adult↗