1,721,064 research outputs found
Participation of GABA<sub>A</sub>-Mediated Inhibition in Ictallike Discharges in the Rat Entorhinal Cortex
No full textLopantsev, Valeri and Massimo Avoli. Participation of GABAA-mediated inhibition in ictallike discharges in the rat entorhinal cortex. J. Neurophysiol. 79: 352–360, 1998. The spontaneous, synchronous activity induced by 4-aminopyridine (4AP, 50 μM) in the adult rat entorhinal cortex was analyzed with simultaneous field potential and intracellular recordings in an in vitro slice preparation. Four-AP induced isolated negative-going field potentials (interval of occurrence = 27.6 ± 9.9 (SD) s; n = 27 slices) that corresponded to intracellular long-lasting depolarizations (LLDs), and ictallike epileptiform discharges (interval of occurrence = 10.4 ± 5.7 min; n = 27 slices) that were initiated by the negative field potentials. LLDs recorded with K-acetate–filled microelectrodes triggered few action potentials of variable amplitude and had a duration of 1.7 ± 0.8 s ( n = 26 neurons), a peak amplitude of 11.8 ± 5.0 mV ( n = 26 neurons) and a reversal potential of −66.2 ± 3.9 mV ( n = 17 neurons). The ictal discharges studied with K-acetate microelectrodes consisted of prolonged depolarizations (duration = 72.9 ± 44.3 s; peak amplitude = 29.2 ± 11.4 mV; n = 25 neurons) with action-potential firing during both the tonic and the clonic phase. These depolarizations had a reversal potential of −45.3 ± 3.8 mV ( n = 4 neurons). Intracellular Cl−diffusion from KCl-filled microelectrodes made both LLDs and ictal depolarizations increase in amplitude (30.5 ± 8.2 mV, n = 8 and 41.8 ± 9.8 mV, n = 6 neurons, respectively). LLDs recorded with KCl and 2-(trimethyl-amino) N-(2,6-dimethylphenyl)-acetamide (QX-314) microelectrodesreached an amplitude of 36.3 ± 5.2 mV, lasted 12.5 ± 6.5 s, and had a reversal potential of −31.3 ± 2.5 mV ( n = 4 neurons); under these recording procedures the ictal discharge amplitude was 41.5 ± 5.0 mV and the reversal potential −24.0 ± 7.0 mV ( n = 4 neurons). The N-methyl-d-aspartate (NMDA) receptor antagonist 3,3-(2-carboxy-piperazine-4-yl)-pro-pyl-l-phosphonate (10 μM, n = 5 neurons) alone or concomitant with the nonNMDA receptor antagonist 6-cyano-7-nitro-quinoxaline-2,3-dione (10 μM, n = 4 neurons) abolished ictal discharges, without influencing LLDs. LLDs were blocked by the γ-aminobutyric acid-A (GABAA) receptor antagonist bicuculline methiodide (BMI, 10 μM, n = 6 neurons) or the μ-opioid receptor agonist (d-Ala2-N-Me-Phe, Gly-ol) enkephalin (DAGO, 10 μM, n = 2 neurons). Application of BMI ( n = 4 neurons) or DAGO ( n = 2 neurons) to control the medium abolished LLDs and ictal discharges but disclosed a novel type of epileptiform depolarization that lasted 3.5 ± 1.2 s and occurred every 5.2 ± 2.6 s ( n = 6 neurons). Our data indicate that 4AP induces in the rat entorhinal cortex a synchronous, GABA-mediated potential that is instrumental in initiating NMDA-dependent, ictal discharges. Moreover we present evidence for an active role played by GABAA-mediated potentials in the maintenance and termination of these prolonged epileptiform events.</jats:p
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
Receptors Causes a Depolarizing Potential Under Physiological Conditions in Rat Hippocampal Pyramidal Cells
No full text- …
