1,720,960 research outputs found
Amphetamine modulation of long term object recognition memory in rats: Influence of stress
No full textAmphetamine is a potent psychostimulant which increases the release of norepinephrine, a neurotransmitter crucially involved in the regulation of memory for stressful experiences. Here we investigated amphetamine effects on consolidation of long term object recognition memory in rats exposed to different stressful conditions. In a second set of experiments, we evaluated whether such effects were dependent on the activation of the peripheral adrenergic system. Immediately after training, adult male Sprague Dawley rats were injected with amphetamine (0.5 – 1 mg/Kg), and submitted to 1 min (25 ± 1 °C) or to 5 min (19 ± 1 °C) forced swim stress (mild and strong stressful conditions, respectively). Retention tests were performed 24 h later. Amphetamine enhanced memory consolidation in rats subjected to the mild stress condition while impairing it in rats subjected to strong stress after training. These dichotomic effects seem to depend on the stress induced activation of the peripheral adrenergic response. In rats unable to synthetize epinephrine (subjected to surgical removal of adrenal medulla) we found opposite effects. In the mild stress condition amphetamine not only lost the capability to enhance memory consolidation but it impaired memory performances, whereas in rats subjected to strong stress after training it ameliorated memory discrimination. Our results are in line with the inverted U-shaped relationship existing between stress levels and memory performances, underlining that the peripheral adrenergic response is a key player in the modulation of amphetamine modulation of long term memory
Amphetamine and the “bath salt” 3,4-methylenedioxypyrovalerone (MDPV) differentially affect the accuracy of memory for emotional experiences in rats
No full textDrugs of abuse have long been recognized to affect memory processes. Here we tested the effects of two psychostimulants, Amphetamine and the “bath salt” MDPV, on the accuracy of memory. We used the inhibitory avoidance (IA) discrimination task, a novel variant of the IA task suitable to study memory accuracy in rodents. Rats were trained and tested in three different contextually modified IA boxes, two visited during the training session and one visited only during the test session. Amphetamine and MDPV had differential effects on memory strength, but both drugs increased generalization of memory for emotional training throughout a differential modulation of the monoaminergic neurotransmissions
Endocannabinoid modulation of short-term recognition memory in rats: Influence of stress and circadian rhythm
No full textBackground: The endocannabinoid system plays a key role in the control of emotional responses to environmental challenges. We previously demonstrated that different stress intensities, experienced soon after encoding, influenced rat short-term memory in an object-recognition task, and that systemic injection of the anandamide hydrolysis inhibitor URB597 reverted the impairing effects, in a stress- and circadian-dependent manner. The effects of stress on the endocannabinoid system are regionally specific and dependent on time.
Methods: Here, we examined whether two different stress intensities and circadian fluctuations on endocannabinoid components modulate short-term memory in the hippocampus, a brain region crucially involved in the modulation of memory. Hippocampal anandamide and 2-arachidonoylglycerol (2-AG) content and the activity of their degrading enzymes, FAAH and MAGL (respectively), were measured.
Results: Independently of the time of the day, stress exposure induced an overall decrease of hippocampal anandamide levels. No significant changes were observed in FAAH activity. Exposure to the high stress condition decreased hippocampal 2-AG and, accordingly, increased MAGL activity, selectively when animals were tested in the afternoon. To further investigate hippocampal 2-AG modulation of short-term recognition memory, rats were given bilateral intra-CA1 administration of the 2-AG inhibitor KML29 immediately after the training trial and were thereafter subjected to a forced swim stress under low or high stress conditions. Low stress exposure impaired 1-hr recognition memory performance when animals were tested in the morning. Exposure to high stress impaired memory performance independently of the time of testing.
Discussion: KML29 counteracted the detrimental effects of stress on short-term recognition memory
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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