1,720,955 research outputs found
Normal Interhemispheric Inhibition in Persistent Developmental Stuttering
No full textImaging studies suggest a right hemispheric (pre)motor overactivity in patients with persistent developmental stuttering (PDS). The interhemispheric inhibition (IHI) studied with transcranial magnetic stimulation is an established measure of the interplay between right and left motor areas. We assessed IHI in 15 young Male adults with PDS and 15 age-matched fluent-speaking subjects. We additionally studied the ipsilateral silent period (iSP) duration. We found no significant between-group difference for IHI or tor iSP duration. We conclude that the interplay between the primary motor cortices is normal in patients with PDS. The abnormal right motor and premotor activity observed in functional imaging studies on PDS are not likely to reflect altered primary motor cortex excitability, hot are likely, to have a different origin. (C) 2009 Movement Disorder Societ
Carbamazepine reduces short-interval interhemispheric inhibition in healthy humans
No full textOBJECTIVE: We sought to elucidate the influence of centrally active drugs on interhemispheric inhibition (IHI) between primary motor cortices in healthy humans.
METHODS: We therefore studied IHI before and 2h after intake of a single oral dose of carbamazepine, dextrometorphane, lorazepam, or placebo and compared it with the well known results for short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). Drugs were tested in separate sessions and in random order.
RESULTS: While SICI and ICF were not altered by carbamazepine, IHI was reduced at the interstimulus interval of 8 ms. Dextrometorphane tended to enhance SICI and to reduce ICF and had no effect on IHI. Lorazepam reduced ICF as expected and enhanced IHI at the long intervals of 50 and 80ms. A moderate trend for interhemispheric facilitation was inconsistently observed at the interval 2 ms and blocked by carbamazepine. In addition, carbamazepine increased the motor threshold.
CONCLUSIONS: We conclude that circuits mediating short interstimulus intervals of IHI are susceptible to sodium channel blockade.
SIGNIFICANCE: The results increase our knowledge of interhemispheric transmission
Investigation of functional connectivity between the left- and right-hemispheric primary motor cortex in stutterers using transcranial magnetic stimulation
No full textDas idiopathische Stottern betrifft ca. 5 % der Kinder im Alter von drei bis sechs Jahren. Diese Zeit stellt einen Abschnitt in der Entwicklung dar, der für den Erwerb von Sprache sehr bedeutend ist. Die meisten stotternden Kinder erleben eine spontane Remission ihrer Symptome, sodass nach der Pubertät nur noch 1 % der Bevölkerung betroffen ist (Chronisch idiopathisches Stottern (CIS)). Da das Stottern bei Mädchen häufiger remittiert als bei Jungen, besteht eine Geschlechterverteilung im Erwachsenenalter von 1 zu 3 - 4. Charakteristisch für das Stottern sind primäre Symptome wie die Repetition und Prolongation, Sprachblocks und das Umschreiben schwieriger Wörter. Als erlerntes Verhalten dieser Symptome bestehen sekundär Flucht- und Vermeidungsverhalten, sowie Sprachangst und Depression. Die Funktion der in bildgebenden Studien nachgewiesenen erhöhten Aktivität motorischer und prämotorischer Areale der rechten Hemisphäre bei Stotternden ist noch nicht vollständig geklärt. Sie könnte einerseits ursächlich für das Auftreten der Stottersymptome sein, andererseits auch als Kompensation für strukturelle Veränderungen der linken Hemisphäre wirken. Wir vermuteten, dass die Ursache der erhöhten rechtshemisphärischen Überaktivität eine verminderte Hemmung derselben durch die linke Hemisphäre über das Corpus callosum ist. Es bestünde somit ein gestörtes Zusammenspiel beider Hemisphären. Das transkallosale Zusammenspiel der motorischen Areale beider Hemisphären haben wir mit Hilfe der Messung der interhemisphärischen Inhibition (IHI) mit transkranieller magnetischer Stimulation (TMS) bei 15 stotternden und 15 nicht-stotternden erwachsenen männlichen Rechtshändern untersucht. Das Untersuchungsprotokoll setzte sich aus dem Doppelreizparadigma zur Ermittlung der Interhemisphärischen Inhibition mit und ohne Voraktivierung des zum konditionierenden Reiz kontralateralen Muskels und der Messung der Dauer und Latenz der ipsilateralen Silent Period (iSP) zusammen. Die Auswertung der Ergebnisse ergab, dass keine signifikanten Unterschiede beider Gruppen bezüglich des Grades der Inhibition bei den Messungen der IHI in Ruhe und unter tonischer Voranspannung sowie bei der Ermittlung der iSP-Dauer bestehen. Somit ist die Haupthypothese negativ. Daraus schließen wir, dass das Zusammenspiel der Motorcortices bei Stotternden regelrecht erfolgt. Die in bildgebenden Studien gesehenen funktionellen und strukturellen Unterschiede müssen also auf einer anderen Ebene liegen, die durch die TMS nicht erfasst wird. Anhand der TMS können lediglich primärmotorische Areale untersucht werden. Im Gegensatz zur Messung der iSP-Dauer, zeigten die Ergebnisse der iSP-Latenz einen signifikanten Unterschied beider Gruppen. Es zeichnete sich eine verminderte Latenz der iSP der 15 Patienten gegenüber den 15 Kontrollpersonen über der rechten Hemisphäre ab. Die Latenz kann Informationen über interhemisphärische und absteigende Faserverbindungen geben. Eine Ursache dieses Gruppenunterschiedes könnten Veränderungen der weißen Substanz sein, die durch bildgebende Verfahren dargestellt wurden. Aufbauend auf diesen Ergebnissen sollte in Zukunft nach Faserveränderungen des koticospinalen Traktes und des Hirnstamms gesucht werden. Diese könnten als weiterleitendes Organ der rechtshemisphärischen Information verändert sein.Stuttering affects up to 5% of children aged 3 to 6 years. This period is known to be sensitive for language acquisition. The majority of these children experience a spontaneous recovery during the following years. Therefore stuttering persists after puberty only in about 1 % of the general population (persistent developmental stuttering (PDS)). Since the stuttering recover more often in girls than in boys there is a female to male ratio of about 1 to 3-4. The PDS shows primary symptoms like repetitions and prolongations of phonemes as well as speech blocks. These symptoms are accompanied by variable secondary symptoms including grimacing, other movements and avoidance behavior. Imaging studies suggest a right-hemispheric motor- and premotor overactivity and left- hemispheric white matter disturbance in patients with PDS. The function of the right-hemispheric overactivity is not completely understood. On the one hand it could be causally related to stuttering, or act as compensation for left-hemispheric structural deficit. We expected the abnormally increased right hemispheric motor and premotor activity to be caused by less inhibition of right hemisphere by the left hemisphere. An established way to assess the transcallosal, interhemispheric interaction of primary motor cortices is the interhemispheric inhibition measured by transcranial magnetic stimulation (TMS). IHI determines the interplay between primary motor cortices. We investigated 15 male adults with PDS and 15 fluent-speaking subjects measuring the interhemispheric inhibition (IHI) and the duration and latency of the ipsilateral silent period (iSP). For IHI and iSP duration we found no significant difference between groups for either hemisphere. Therefore the results do not indicate an abnormal interplay between the primary motor cortices in PDS. The right-hemispheric motor- and premotor overactivity do not reflect altered primary motor cortex excitability, but are likely to have a different origin. Using TMS it is only possible to examine the motor cortex. The analysis of the iSP latency yielded an unexpected result: The stuttering subjects showed a shorter latency than the control group with the test pulse over the right hemisphere. The latency gives information of interhemispheric and descending fiber tracts. The significant difference between groups could be causally related to white matter disturbance or pre motor differences observed in imaging studies on PDS. In summary, our results make the interplay between the primary motor cortices less likely to play a role in PDS, whereby efferent fibers could be disturbed. Based on these results it is likely to examine the pyramidal tract and the brainstem as they could conduct altered information of the right hemisphere
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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