1,721,058 research outputs found
Eye movement impairment after central thalamus lesions
No full textAnimal studies suggest that the central thalamus is involved in the control of eye movements that are based on extraretinal signals. In humans, there is only one recent paper that describes two patients with a lesion located within the intramedullary nuclei, in which visual memory-guided saccades were normal but became inaccurate when the eyes were displaced between target disappearance and saccade triggering, that is, when an extraretinal position signal had to be taken into account. We studied visual and auditory saccades recorded monocularly with the magnetic search coil technique in three patients with an isolated lesion located in the central thalamus. Visual saccades proved to be normal, whereas for auditory stimuli, saccade duration and peak velocity were normal but the amplitude of the first saccade was asymmetrical: saccades ipsilateral to the lesion were significantly smaller than those directed to the contralateral side. The patients were able to make corrective saccades and, hence, to improve gain and to decrease gain asymmetry. We suggest that patients were able to localize auditory targets correctly, did not correctly take into account eye position during the saccade, probably as a consequence of an inaccurate efference copy (corollary discharge) signal. Our findings are in keeping with the hypothesis that the central thalamus deals with saccades that are based on extraretinal signals
Multiple meningiomas evaluated by computed tomography
No full textThe authors report ten cases of multiple meningiomas in a series of 227 intracranial meningiomas from 1977 to 1984. The incidence of multiple meningiomas was 4.4% (according to Cushing and Eisenhardt's [1938] concept of 'multiplicity' of such tumours). These results are comparable to those obtained by other authors. All patients were females and all underwent CT scan before operation. Clinical symptoms are presented along with location and size of the tumours. Pathogenetic theories and research prospects are discussed
Auditory saccade impairment after central thalamus lesions
No full textVisual and auditory saccades were studied in three patients with an isolated lesion located in the central thalamus. Visual saccades proved to be normal, whereas for auditory stimuli, the amplitude of the first saccade was asymmetric: saccades ipsilateral to the lesion were significantly smaller than those directed to the contralateral side. The patients were able to make a corrective saccade and hence to improve gain and to decrease gain asymmetry. It is suggested that patients were able to localise auditory targets correctly, but did not correctly take into account eye position during the saccade, probably as a consequence of an inaccurate efference copy (corollary discharge) signal. The findings are in keeping with the hypothesis that the central thalamus deals with saccades that are based on extraretinal signals
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
Towards improved clinical characterization of Leber congenital amaurosis: neurological and systemic findings.
No full textLeber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophy that presents in infancy. LCA is both clinically and genetically heterogeneous. The aim of our study was to clarify the clinical aspects of LCA and to contribute to improved characterization of the disorder. We studied 40 children affected by LCA (mean age at first observation: 19 months, range: 8-50 months), who underwent a comprehensive evaluation that included: neurophthalmological evaluation, electroretinogram (ERG), and visual evoked potentials (VEPs), general and neurological examinations, developmental assessment using scales for visually impaired children, neuroradiological examinations, hepatic and renal function and metabolic investigations, brainstem auditory evoked potentials (BAEPs), EEG, and hand radiographs. Analyses of known LCA genes are ongoing. The subjects are still being followed up at 6-/12-month intervals. All the subjects fulfilled De Laey's criteria for LCA. The neurological examination was abnormal in 31 cases (hypotonia, ataxia with/without associated cerebellar signs). Cognitive development was normal in 24 cases, borderline in five, and subnormal in 11. Mild and nonspecific alterations on MRI were present in seven cases, and "molar tooth" sign in four; all the others had a normal neuroradiological picture. Among the subjects presenting with neurological signs, a subgroup (13 patients) emerged that was characterized by systemic (skin, kidney, liver) involvement. Our data confirm that LCA is a heterogeneous entity that can present as an isolated ocular manifestation, or in association with neurological and systemic abnormalities and support the need for a multidisciplinary approach to this entity and for genotype-phenotype studies
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
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