1,720,973 research outputs found
Measuring disease progression in corticobasal syndrome
No full textCorticobasal syndrome (CBS) is a complex neurodegenerative disorder with marked clinical, neuropsychological, and pathological heterogeneity. Measurement of disease progression in CBS is complex and little understood. This study aimed to establish clinical and neuropsychological indicators of prognosis in CBS. Patients with CBS were retrospectively recruited from a frontotemporal dementia specific research clinic. All patients underwent detailed clinical and neuropsychological testing including the frontotemporal dementia rating scale (FRS). Using the differences in FRS logit scores over a period of 12 months, CBS patients were divided into rapid and slow progressor groups. Demographic, clinical and neuropsychological features were compared between the two groups. Sixteen participants who met defined criteria were included (9 males, 7 females; mean age 65.8 ± 22 years; median symptom duration 51.8 ± 22 years; mean duration of follow-up 11.4 ± 2.8 months). There were no significant differences between the rapid and slow progressors in age, gender, symptom duration, motor/cognitive presentation, and ACE-R scores at baseline. Clinically, slow progressors were significantly more likely to have a motor speech disorder, with a trend for more frequent dysgraphia, whereas rapid progressors were more likely to exhibit surface dyslexia. Rapid and slow progressor groups did not differ on neuropsychological performance. The presence of motor speech disorder, dysgraphia, and surface dyslexia may be useful in differentiating patients with rapid progression of CBS from those with a more indolent disease course
Apraxia and motor dysfunction in corticobasal syndrome
No full textBackgroundCorticobasal syndrome (CBS) is characterized by multifaceted motor system dysfunction and cognitive disturbance; distinctive clinical features include limb apraxia and visuospatial dysfunction. Transcranial magnetic stimulation (TMS) has been used to study motor system dysfunction in CBS, but the relationship of TMS parameters to clinical features has not been studied. The present study explored several hypotheses; firstly, that limb apraxia may be partly due to visuospatial impairment in CBS. Secondly, that motor system dysfunction can be demonstrated in CBS, using threshold-tracking TMS, and is linked to limb apraxia. Finally, that atrophy of the primary motor cortex, studied using voxel-based morphometry analysis (VBM), is associated with motor system dysfunction and limb apraxia in CBS.MethodsImitation of meaningful and meaningless hand gestures was graded to assess limb apraxia, while cognitive performance was assessed using the Addenbrooke's Cognitive Examination – Revised (ACE-R), with particular emphasis placed on the visuospatial subtask. Patients underwent TMS, to assess cortical function, and VBM.ResultsIn total, 17 patients with CBS (7 male, 10 female; mean age 64.4+/− 6.6 years) were studied and compared to 17 matched control subjects. Of the CBS patients, 23.5% had a relatively inexcitable motor cortex, with evidence of cortical dysfunction in the remaining 76.5% patients. Reduced resting motor threshold, and visuospatial performance, correlated with limb apraxia. Patients with a resting motor threshold <50% performed significantly worse on the visuospatial sub-task of the ACE-R than other CBS patients. Cortical function correlated with atrophy of the primary and pre-motor cortices, and the thalamus, while apraxia correlated with atrophy of the pre-motor and parietal cortices.ConclusionsCortical dysfunction appears to underlie the core clinical features of CBS, and is associated with atrophy of the primary motor and pre-motor cortices, as well as the thalamus, while apraxia correlates with pre-motor and parietal atrophy
Clinical profile of PiB-positive Corticobasal syndrome
No full textBackground: Corticobasal syndrome (CBS) is a multifaceted neurodegenerative disorder characterized by a combination of motor and cognitive deficits. Several different pathological entities, including Alzheimer's pathology, have been described in association with CBS. The present study aimed to establish clinical, neuropsychological, and neuroimaging features that could be useful in the distinction of CBS due to AD pathology from other CBS cases in life based on [11C] Pittsburgh Compound B positron emission tomography (PiB-PET) status. Methods: Patients with CBS were prospectively recruited from a specialized cognitive disorders clinic. All patients underwent detailed clinical and neuropsychological assessment, with structural imaging using voxel-based analysis of magnetic resonance imaging. Alzheimer's pathology was detected using PiB-PET imaging, and PiB-positive and PiB-negative groups were compared. Results: Fourteen CBS patients meeting defined criteria were included (7 male, 7 female; mean age 66.1+/-6.9 years; median symptom duration was 35.5+/-22.6 months) and compared to 20 matched control subjects. Of the 14 patients, 4 were PiB-positive and 10 PiB-negative. There were no significant differences between PiB-positive and PiB-negative CBS patients in age, gender, education, symptom duration, or motor features. PiB-positive patients had greater visuospatial deficits, a higher rate of sentence repetition impairment, and more functional decline. Voxel-based morphometry analyses demonstrated extensive peri-insular and post-central atrophy in both groups, but PiB-positive patients had atrophy that extended to include the posterior part of the left superior temporal gyrus. Conclusions: Visuospatial function, aspects of language, and the pattern of cerebral atrophy may be useful in distinguishing patients with CBS due to underlying AD pathology
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Grey and white matter changes across the amyotrophic lateral sclerosis-frontotemporal dementia continuum
No full textThere is increasing evidence that amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) lie on a clinical, pathological and genetic continuum with patients of one disease exhibiting features of the other. Nevertheless, to date, the underlying grey matter and white matter changes across the ALS-FTD disease continuum have not been explored. In this study fifty-three participants with ALS (n = 10), ALS-FTD (n = 10) and behavioural variant FTD (bvFTD; n = 15) as well as controls (n = 18), underwent detailed clinical assessment plus structural imaging using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) analysis of magnetic resonance brain imaging to examine grey and white matter differences and commonalities across the continuum. Importantly, patient groups were matched for age, education, gender and disease duration. VBM and DTI results showed that changes in the ALS group were confined mainly to the motor cortex and anterior cingulate as well as their underlying white matter tracts. ALS-FTD and bvFTD showed widespread grey matter and white matter changes involving frontal and temporal lobes. Extensive prefrontal cortex changes emerged as a marker for bvFTD compared to other subtypes, while ALS-FTD could be distinguished from ALS by additional temporal lobe grey and white matter changes. Finally, ALS could be mainly distinguished from the other two groups by corticospinal tract degeneration. The present study shows for the first time that FTD and ALS overlap in anterior cingulate, motor cortex and related white matter tract changes across the whole continuum. Nevertheless, frontal and temporal atrophy as well as corticospinal tract degeneration emerged as marker for subtype classification, which will inform future diagnosis and target disease management across the continuum
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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