1,721,039 research outputs found
Role of muscarinic receptors in the cerebellar control of the vestibulospinal reflex gain: cellular mechanisms.
No full textAbstract
Most of the inhibitory Purkinje (P-) cells of the cerebellar anterior vermis fire out-of-phase with respect to the excitatory vestibulospinal neurons during roll tilt of the animal, thus exerting a positive influence on the gain of the vestibulospinal reflex (VSR). The responses of these P-cells depend on activation of glutamatergic excitatory mossy fibers-granule cells, but they are likely to be shaped by GABAergic inhibitory interneurons. The cerebellar cortex contains cholinergic fibers and both muscarinic and nicotinic receptors. In decerebrate cats intravermal injection of the muscarinic agonist bethanechol increased the VSR gain. The cellular mechanisms underlying these gain changes were studied in anesthetized Sprague-Dawley rats by microiontophoresis. Application of bethanechol (10-60 nA, 300 s) increased the response of vermal P-cells to pulses of glutamate (22/33 cells) or GABA (23/25 cells). These effects, which were blocked by the muscarinic antagonist scopolamine, lasted up to 15-40 min and occurred regardless of whether bethanecol altered the basal firing rate of the cells. We propose that the increase of P-cell responses to both excitatory and inhibitory neurotransmitters following activation of muscarinic receptors enhances the amplitude of modulation of these neurons to animal tilt, thus increasing the gain of the VSR
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
The muscarinic agonist, bethanechol, enhances GABA-induced inhibition of Purkinje cells in the cerebellar cortex.
No full textAbstract
An important function of cholinergic projections to the cerebellar cortex may be to modulate the effects of classical afferent inputs to the cerebellar cortex. This hypothesis is supported by the recent observation that cholinergic agonists act at muscarinic receptors in the cerebellar cortex to facilitate Purkinje cell responses to glutamate, the excitatory neurotransmitter of parallel fibers [Brain Res., 617 (1993) 28-36]. Since Purkinje cell excitability is influenced by inhibitory input from basket and stellate cells as well as by excitatory input from granule cells and climbing fibers, the present study investigated whether muscarinic agonists could also modify the Purkinje cell responses to GABA, the putative inhibitory transmitter of basket and stellate neurons. In anesthetized ratrs, microiontophoretic application of bethanechol produced a long-lasting enhancement of GABA-evoked inhibition of firing of Purkinje cells in the cerebellar vermis (22/25 cells) regardless of whether bethanechol increased, decreased or failed to alter the basal firing rate of the cell. The muscarinic antagonist scopolamine prevented the bethanechol-induced increase in the GABA response. It appears, therefore, that cholinergic activation of muscarinic receptors enhances not only the excitatory but also the inhibitory component of cerebellar cortex circuitry. Further experiments are required to investigate whether this combination of effects may potentiate the signal processing capabilities of the cerebellar cortex
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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