1/13. Residual perceptual distortion in 'recovered' hemispatial neglect.In most neglect patients, line bisection errors become smaller on repeated tests over the months following the lesion. We have tried to determine in two typical patients whether this is because of a real reduction in the perceptual distortions that appear to underlie line bisection errors in neglect, or whether it reflects a learned behavioural strategy to counteract those perceptual biases. We tested the patients on two occasions (2 and 12 months post-stroke), on line bisection and also on the 'Landmark' task. The data indicated that at the first testing session both patients showed strong 'perceptual' neglect, making large rightward errors in the standard bisection task and uniformly leftward pointing in the Landmark task. On the second occasion, as expected, both patients showed a marked recovery when tested with the line bisection task, making only very small errors. In contrast, their landmark performance was still markedly biased in the same direction as before. These findings suggest that despite their apparent recovery on the bisection task, both patients still experience some form of perceptual distortion of horizontal lines. It is suggested that the Landmark task may provide a sensitive means for identifying real recovery of the underlying perceptual deficit.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
2/13. Two types of auditory neglect.Auditory neglect, defined as inattention to stimuli within the left hemispace, is mostly reported in association with left ear extinction in dichotic listening. However, it remains disputed as to how far dichotic extinction reflects a primary attentional deficit and is thus appropriate for the diagnosis of auditory neglect. We report here on four patients who presented left ear extinction in dichotic listening following right unilateral hemispheric lesions. Auditory spatial attention was assessed with two additional tasks: (i) diotic test by means of interaural time differences (ITDs), simulating bilateral simultaneous spatial presentation of the dichotic tasks without the inconvenience of interaural intensity or content difference; and (ii) sound localization. A hemispatial asymmetry on the ITD diotic test or a spatial bias on sound localization were found to be part of auditory neglect. Two patients (J.C.N. and M.B.) presented a marked hemispatial asymmetry favouring the ipsilesional hemispace in the ITD diotic test, but did not show any spatial bias in sound localization. Two other patients (A.J. and E.S.) had the reverse profile: no hemispatial asymmetry in the ITD diotic test, but a severe spatial bias directed to the ipsilesional side in sound localization. J.C.N. and M.B. had mainly subcortical lesions affecting the basal ganglia. A.J. and E.S. had cortical lesions in the prefrontal, superior temporal and inferior parietal areas. Thus, there are two behaviourally and anatomically distinct types of auditory neglect characterized by: (i) deficit in allocation of auditory spatial attention following lesions centred on basal ganglia; or (ii) distortion of auditory spatial representation following frontotemporoparietal lesions.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
3/13. Unilateral spatial neglect associated with chronic subdural haematoma: a case report.A 69-year-old right-handed man who exhibited unilateral spatial neglect in association with a chronic subdural haematoma, presented with mild left arm and leg weakness first noted 4 weeks prior to admission. neurologic examination on admission revealed a mild left hemiparesis, including the face. Neuropsychologic examination revealed left unilateral spatial neglect, but no language disturbance. Minimal support was necessary to maintain activities of daily living. Computed tomography revealed a large right temporoparietal, extraaxial hypodense fluid collection containing scattered hypodense foci. The haematoma was evacuated via a right parietal burr hole. Following surgery, the patient dramatically improved neurologically and neuropsychologically, as well as in independent performance of daily activities. It is suggested that the improvement in ADL provides a behavioural correlate of improvement in the latter, represented a behavioural correlate of improved cerebral function, and that either direct compression by the chronic subdural haematoma or an interhemispheric pressure difference had caused unilateral spatial neglect. Such neglect is an unusual consequence of chronic subdural haematoma.- - - - - - - - - - ranking = 2keywords = behaviour (Clic here for more details about this article) |
4/13. Disordered recognition of facial identity and emotions in three Asperger type autists.In this report we aim to explore severe deficits in facial affect recognition in three boys all of whom meet the criteria of Asperger's syndrome (AS), as well as overt prosopagnosia in one (B) and covert prosopagnosia in the remaining two (C and D). Subject B, with a familially-based talent of being highly gifted in physics and mathematics, showed no interest in people, a quasi complete lack of comprehension of emotions, and very poor emotional reactivity. The marked neuropsychological deficits were a moderate prosopagnosia and severely disordered recognition of facial emotions, gender and age. Expressive facial emotion, whole body psychomotor expression and speech prosody were quasi absent as well. In all three boys these facial processing deficits were more or less isolated, and general visuospatial functions, attention, formal language and scholastic performances were normal or even highly developed with the exception of deficient gestalt perception in B. We consider the deficient facial emotion perception as an important pathogenetic symptom for the autistic behaviour in the three boys. prosopagnosia, the absent facial and bodily expression, and speech prosody were important but varying co-morbid disorders. The total clinical picture of non-verbal disordered communication is a complex of predominantly bilateral and/or right hemisphere cortical deficits. Moreover, in B, insensitivity to pain, smells, noises and internal bodily feelings suggested a more general emotional anaesthesia and/or a deficient means of expression. It is possible that a limbic component might be involved, thus making affective appreciation also deficient.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
5/13. First saccades reveal biases in recovered neglect.Hemispatial neglect affects the ability to explore space on the side opposite a brain lesion. This deficit is also mirrored in abnormal saccadic eye movement patterns. The present study investigated if the recovery of neglect is also reflected in saccadic eye movements. Patient AF, who displayed strong hemispatial neglect 1 month post-right thalamic stroke, had largely recovered 3 months later when tested on visual exploration tasks of the Behavioural Inattention Test. At this stage, AF was tested on a visual search task while his eye movements (direction, latencies and amplitudes of first saccades) and manual reaction times were recorded. The experimental conditions differed with respect to stimulus number and distracter type and increased in difficulty. AF correctly generated saccades into the neglected field when the target was presented alone. In contrast, a considerable left/right difference was present for all multiple-stimulus search displays. Although recovered from neglect in standardized assessment, AF showed a strong rightward bias resulting in highly asymmetric response times and eye movement behaviour. We conclude that eye movement patterns are far more susceptible to remaining spatial impairments and can thus provide a sensitive means to assess the extent of neglect recovery.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
6/13. Assessing unilateral neglect: shortcomings of standard test methods.INTRODUCTION: When investigating the incidence of unilateral neglect in a first-ever stroke population, we found that some patients showed clinical signs of neglect, but managed to pass our tests. The purpose of this paper is to describe the nature of such signs, and analyse why test instruments were insufficiently corresponding to those signs. METHOD: One hundred and thirty-one consecutive patients with first-ever stroke in a community-based sample were evaluated for the presence of unilateral neglect. We used a test battery consisting of tests for visuo-spatial neglect, personal neglect, and anosognosia. Twenty cases of neglect were discovered by standard methods. We asked our collaborators at the wards to report any behavioural abnormality reminiscent of neglect present in patients who had normal test results. Such patients were evaluated clinically. RESULTS: Nine cases with neglect-like symptoms were discovered. Our clinical evaluation of the nine patients indicated several possible explanations for their behavioural abnormalities, including motor neglect, neglect for far extrapersonal space, disturbances of proprioception, and spatial disturbances other than neglect. CONCLUSION: Standard neglect tests do not cover all clinical forms of neglect. It is therefore important not to rely completely on test instruments when diagnosing neglect. More versatile test instruments are desired.- - - - - - - - - - ranking = 2keywords = behaviour (Clic here for more details about this article) |
7/13. A case of unilateral neglect in Huntington's disease.Unilateral neglect, an attentional deficit in detecting and acting on information coming from one side of space, is a relatively common consequence of right hemisphere stroke. Although neglect has been observed following damage to a variety of brain structures, to date no reports exist of neglect phenomena arising from Huntington's disease (HD). However, reports in the animal and human literature suggest that neglect is possible following damage to a primary site for Huntington's pathology, the basal ganglia. Here we present a patient (BG) with genetically proven HD who, in the context of the mild intellectual, executive and attentional impairments associated with the disorder, showed a remarkably severe and stable neglect for left space. MRI and electrophysiological results make it unlikely that the spatial bias could be accounted for by basic sensory loss. In addition, behavioural investigation indicated that, although BG's neglect operated in a very striking manner along body-centred co-ordinates (missing almost all information presented to her left), more general limitations in visual attention were apparent to the left-side of information presented entirely to the right of the body midline. Further evidence is presented showing that the neglect was manifest on tactile and auditory tasks as well as those presented in the visual domain. The presence of neglect in HD in this case is novel and somewhat puzzling, particularly as flourodeoyglucose positron emission tomography revealed bilateral caudate hypoperfusion. Reducing the statistical threshold on this analysis revealed a potential frontal hypometabolism that was more marked in the right than left hemisphere. However, as this was only apparent at a threshold below that normally considered acceptable (due to the resulting number of false positives), this possible account of the neglect must be viewed very cautiously.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
8/13. Observations on the human rejection behaviour syndrome: Denny-Brown revisited.The parietal avoiding-rejection behaviour syndrome, first described by Denny-Brown in the rhesus monkey, has been reported only rarely in humans. Here, we describe a patient with rejection behaviour in the setting of progressive cognitive decline accompanied by cortical myoclonus.- - - - - - - - - - ranking = 6keywords = behaviour (Clic here for more details about this article) |
9/13. The space of senses: impaired crossmodal interactions in a patient with Balint syndrome after bilateral parietal damage.Balint syndrome after bilateral parietal damage involves a severe disturbance of space representation including impaired oculomotor behaviour, optic ataxia, and simultanagnosia. Binding of object features into a unique spatial representation can also be impaired. We report a patient with bilateral parietal lesions and Balint syndrome, showing severe spatial deficits in several visual tasks predominantly affecting the left hemispace. In particular, we tested whether a loss of spatial representation would affect crossmodal interactions between simultaneous visual and tactile events occurring at the same versus different locations. A tactile discrimination task, where spatially congruent or incongruent visual cues were delivered near the patient's hands, was used. Following stimulation of the left hand in the left side of space, we observed visuo-tactile interactions that were not modulated by spatially congruent conditions. In contrast, performance following stimulation of the right hand in the right side of space was affected in a spatially selective manner--facilitated for congruent stimuli and slowed for incongruent stimuli. To dissociate effects on somatotopic and spatiotopic coordinates, we crossed the patient's hands during unimodal tactile discriminations. Tactile performance of the left hand improved when it was positioned in the right hemispace, whereas placing the right hand in left space produced no significant changes, suggesting that left-sided tactile inputs are coded with respect to a combination of limb- and trunk-centred coordinates. These data converge with recent findings in animals and healthy humans to indicate a critical role of the posterior parietal cortex in multimodal spatial integration, and in the fusion of different coordinates into a unified representation of space.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
10/13. Posterior callosal section in a non-epileptic patient.The major studies of the effects of callosal section in humans have been conducted in severe epileptic patients in whom commissurotomy has been performed for management of intractable seizures. In spite of the evidence which has been amassed it is possible to criticise the results, on the grounds that all patients had seizures for many years prior to surgery and hence it is conceivable that some adaptive reorganisation of the epileptic brain might account for the different behaviour of the two hemispheres. Specifically, since the primary epileptic focus and its possible underlying focal damage are often asymmetric, one hemisphere might have had to adapt to the functional deficit of the other and thereby produce the basis for the unusually striking hemispheric differences. The answer to these reservations must come from the study of non-epileptic subjects who undergo some form of commissurotomy for reasons other than treatment of seizures, particularly if the intervention involves the posterior third of the corpus callosum, the sector considered responsible for the more remarkable "disconnection" signs. Only seven such cases have been reported. Here we report findings in a non-epileptic and previously normal 16-year-old boy who underwent section of the splenium for exploration of a pineal tumour. Our results indicate that surgical section of the splenium produced visual disconnection signs comparable to those seen in epileptic patients with complete commissurotomy.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
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