1,720,958 research outputs found
Paired-pulse repetitive transcranial magnetic stimulation of the human motor cortex
No full textIn nine healthy humans we modulated corticospinal excitability by using conditioning-test paired-pulse transcranial magnetic stimulation in a repetitive mode (rTMS), and we compared its effect to conventional single-pulse rTMS. We applied 80 single pulses or 80 paired pulses to the motor cortex at frequencies ranging from 0.17 to 5 Hz. The conditioning-test intervals were 2, 5, or 10 ms. Motor evoked potential (MEP) amplitudes from the abductor digiti minimi (ADM) as target muscle and extensor carpi radialis (ECR) indicated the excitability changes during and after rTMS. During paired-pulse rTMS at a facilitatory conditioning-test interval of 10 ms, we observed a facilitation of MEPs at 1, 2, and 5 Hz. A similar facilitation was found during single-pulse rTMS, when stimulus intensity was adjusted to evoke MEPs of comparable size. Using an inhibitory conditioning-test interval of 2 ms, paired-pulse rTMS at frequencies of 1 and 2 Hz caused no change in MEP size during the train. However, paired-pulse rTMS at 5 Hz caused a strong enhancement of MEP size, indicating a loss of paired-pulse inhibition during the rTMS train. Since no facilitatory effect was observed during single-pulse rTMS with an adjusted stimulus intensity, the MEP enhancement during 5 Hz rTMS was specific for "inhibitory" paired-pulse rTMS. After 5 Hz rTMS MEPs were facilitated for 1 min, and this effect was not substantially different between paired-pulse rTMS and single-pulse rTMS. The correlation between ADM and ECR was most pronounced at 5 Hz rTMS. We conclude that paired-pulse rTMS is a suitable tool to study changes in corticospinal excitability during the course of rTMS. In addition, our data suggest that short trains of paired-pulse rTMS are not superior to single-pulse rTMS in inducing lasting inhibition or facilitation
Normal intracortical excitability in developmental stuttering
No full textPersistent developmental stuttering (PDS) shares clinical features with task-specific dystonias. In these dystonias, intracortical inhibition is abnormally weak. We therefore sought to determine intracortical inhibition and intracortical facilitation in PDS. In 18 subjects with PDS since childhood (mean age, 39.4 [SD 13.0] years) and 18 speech-fluent controls (43.6 [14.3] years), we investigated resting and active motor thresholds as well as intracortical inhibition and facilitation of the optimal representation of the abductor digiti minimi of the dominant hand using transcranial magnetic stimulation. In PDS, the resting and active motor thresholds were increased, whereas intracortical inhibition and facilitation were normal. Normal intracortical excitability makes a pathophysiological analogy between focal dystonia and PDS less likely. The enhanced motor threshold suggests reduced motor cortical neuronal membrane excitability in PDS. (C) 2003 Movement Disorder Society
Treatment of restless legs syndrome with the dopamine agonist alpha-dihydroergocryptine
No full textAn open pilot study with the dopamine agonist alpha -dihydroergocryptine (DHEC) was conducted in 16 patients with idiopathic restless legs syndrome (RLS) over a period of 5 weeks. Following a drug-free interval of 1 week, the patients were treated with daily doses of 10 to 40 mg DHEC. As compared to baseline values, treatment led to a statistically significant reduction of subjective RLS symptoms. Overall complaints at night decreased significantly by 63.9 +/- 38.1% as measured by a visual analogue scale. Detailed evaluation of sensory discomfort, motor restlessness, involuntary movements, as well as sleep quality also showed significant improvement. Side effects were mostly mild and affected mainly the gastrointestinal tract. Five patients needed domperidone for treatment of concomitant nausea. One patient stopped the study due to nausea. In conclusion, the results of this open study suggest a role for DHEC in the treatment of RLS. (C) 2001 Movement Disorder Society
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
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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