ABSTRACT
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.
Subject(s)
Attention/physiology , Auditory Perception/physiology , Cerebrovascular Disorders/psychology , Cognition Disorders/psychology , Acoustic Stimulation , Aged , Biomarkers , Female , Functional Laterality/physiology , Humans , Male , Middle Aged , Movement/physiology , Visual Fields/physiologyABSTRACT
This study was motivated by the fact that unilateral neglect, an impediment to progress in patient rehabilitation, is often reported to occur in a wider area of space than that usually assessed in clinical settings. Neglect within "grasping space" (Halligan & Marshall, 1991; Kolb & Whishaw, 1990) was assessed via two search tasks: one in which search was guided by visual information and the other in which search was guided by tactile information. The performance of 10 left brain-damaged patients (LBD) and 20 right brain-damaged patients, 10 of whom showed left visual neglect (RBD+) while 10 did not (RBD-), was compared with that of age-matched controls. The visual search task confirmed the clinical diagnoses of unilateral visual neglect. On the tactile test, both RBD groups showed reduced search within the left hemispace, although this was a particularly strong feature of the performance of the RBD+ patients. Furthermore, this reduced leftwards exploration in RBD+ patients was associated with an increased frequency of repetitions made within the right hemispace, as had also been noted in some of these patients on conventional visual star cancellation. Results are discussed in relation to hyperattentional theories of directional spatial neglect.
Subject(s)
Attention/physiology , Cognition Disorders/psychology , Touch/physiology , Adult , Aged , Brain Diseases/psychology , Brain Injuries/psychology , Cognition Disorders/etiology , Female , Humans , Male , Middle Aged , Neuropsychological Tests , Space Perception , Visual Perception/physiologyABSTRACT
In this paper the performance of patients with unilateral hemispheric lesions (n = 10 with right brain damage; n = 10 with left brain damage) on a free-field sound localization task was contrasted with that of healthy controls (n = 10). Sound stimuli were presented binaurally in the horizontal plane from eight loudspeakers set at azimuths between -105 degrees and +105 degrees. Whereas performance of both patient groups was generally less accurate than controls, no evidence suggested that this was specific to the contralateral hemisphere. The results indicate that both hemispheres play a role in sound localization, with systematic directional errors made towards the ipsilateral hemifield following unilateral lesions. Furthermore, particular location difficulties at pericentral positions (+15 degrees and -15 degrees) following right hemisphere damage, may indicate a specific function for the right hemisphere in determining personal frames of spatial reference within pericentral space.
Subject(s)
Brain/physiopathology , Brain/surgery , Perceptual Disorders/physiopathology , Sound Localization , Adult , Aged , Female , Humans , Male , Middle AgedABSTRACT
This study investigated the possibility that a specific age at onset factor in Parkinson's disease results in qualitative differences in cognitive functioning between early- and late-onset patients without dementia. Both early- and late-onset patients performed more poorly than matched controls on face-matching, recognition memory for unfamiliar faces and famous face identification. When the performance of the early- and late-onset patients was contrasted, alongside that of controls, both Parkinson's disease and age were found to be factors that influenced cognitive ability. No interaction between these factors emerged. These results suggest that performance of early- and late-onset Parkinson's disease patients without dementia may be quantitatively different and lend no further support to the proposal that two separate disorders exist.
