The neural basis of anosognosia for spatial neglect after stroke.
ABSTRACT The present study investigated the lesion anatomy of anosognosia for visuospatial neglect resulting from right hemispheric stroke.
In 63 patients, self-ratings of performance in paper-and-pencil tests were contrasted with external performance ratings. Lesion analysis was conducted on patient subgroups with different degrees of anosognosia but comparable visuospatial impairment.
Independent of the severity of visuospatial neglect per se, damage to the right angular and superior temporal gyrus was associated with higher levels of anosognosia.
Using a novel assessment of anosognosia for spatial neglect, the present study relates stroke-induced self-awareness deficits to inferior parietal and superior temporal brain damage.
- Revista Espanola de Medicina Legal 04/2014;
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ABSTRACT: Apraxia, a disorder of higher motor cognition, is a frequent and relevant sequel outcome of left hemispheric stroke. Deficient pantomiming of object use constitutes a key symptom of apraxia and is assessed when testing for apraxia. To date the neural basis of pantomime remains controversial. We here review the literature and perform a meta-analysis of the relevant structural and functional imaging (fMRI/PET) studies. Based on a systematic literature search, 10 structural and 12 functional imaging studies were selected. Structural lesion studies associated pantomiming deficits with left frontal, parietal and temporal lesions. In contrast, functional imaging studies associate pantomimes with left parietal activations, with or without concurrent frontal or temporal activations. Functional imaging studies that selectively activated parietal cortex adopted the most stringent controls. In contrast to previous suggestions, current analyses show that both lesion and functional studies support the notion of a left-hemispheric fronto-(temporal)-parietal network underlying pantomiming object use. Furthermore, our review demonstrates that the left parietal cortex plays a key role in pantomime-related processes. More specifically, stringently controlled fMRI-studies suggest that in addition to storing motor schemas, left parietal cortex is also involved in activating these motor schemas in the context of pantomiming object use. In addition to inherent differences between structural and functional imaging studies and consistent with the dedifferentiation hypothesis, the age difference between young healthy subjects (typically included in functional imaging studies) and elderly neurological patients (typically included in structural lesion studies) may well contribute to the finding of a more distributed representation of pantomiming within the motor-dominant left hemisphere in the elderly.NeuroImage: Clinical. 01/2014;
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ABSTRACT: This review provides an overview of research into anosognosia after stroke over the past 35 years. We are specifically interested in the assessment of anosognosia in group studies and in how any changes in assessment procedures have impacted the study of anognosia. Our work is based on a systematic review of reports drawn from electronic databases covering the period from 1978 to 2013 (CINAHL, PubMedMEDLINE, PsycINFO, Web of Knowledge). Sixty-four articles met the selection criteria. The results of our review show that a deeper understanding has evolved of the multifaceted syndrome of anosognosia during the past decade. The most recent studies made more extensive use of research, observational and performance-based procedures as well as traditional interview methods. Modality specifities and patients with language impairment also receive closer consideration than earlier. Furthermore, the results are more often obtained from homogeneous patient groups. The limitations of recent anosognosia research include the diversity of assessment methods used and the variation in the assessment times between and within patient groups, and the tendency to rely on only 1 method to assess and diagnose anosognosia. In order to improve the comparability of anosognosia studies it would be useful to have guidelines for the number and type of assessment methods used in studying different subtypes of anosognosia, and to focus on homogeneous patient samples. Furthermore, it is recommended that more research be done to explore chronic anosognosia and its impact on daily living.Cortex 01/2014; · 6.04 Impact Factor