1,720,963 research outputs found
Interocular transfer of visual discriminations in Wulst-ablated pigeons.
No full textInterocular transfer (IOT) of monocularly learned pattern, brightness and color discriminations was studied in normal pigeons and in pigeons with a bilateral ablation of the visual Wulst. No significant differences were found between the two groups in terms of both rate of monocular learning and degree of IOT. Pigeons with a Wulst ablation which had shown a normal capacity for IOT, subsequently lost this capacity following a section of the supra-optic decussation (DSO). It is concluded that IOT in pigeons does not require the presence of the binocular neurons of the visual Wulst, and that in absence of this structure, IOT must rely on other centers for binocular interaction which receive fibers from the DSO
Protracted withdrawal from alcohol impacts excitability and dynamical properties of neurons of the bed nucleus of stria terminalis
No full textThe juxta-capsular subdivision of bed nucleus of stria terminalis (jcBNST) is part of the extended amygdala and plays an important role in the regulation of stress and reward related behaviors. This compact nucleus contains at least 3 types of biophysically diverse populations of GABAergic neurons that play an important role in the regulation of downstream neural circuits of the central amygdala. While drug-related neuroadaptive changes in the synaptic properties of BNST and other extended amygdala neurons have been well documented, their integrative properties and circuit interactions are also to be studied in order to gain a better understanding of the neurophysiological aspects of addictive behavior. Here we performed a series of dynamic clamp experiments with synthetic presynaptic voltage waveforms that were transformed to simulated excitatory and inhibitory synaptic conductances and injected into jcBNST neurons. This methodological approach allowed us to characterize how the temporal structure of the firing responses and the precision of spike timing depended on the type of neuron and how these properties were modified after prolonged withdrawal in alcohol dependent animals. Additionally, we performed a comprehensive analysis of neuronal responses under standard current clamp stimulation and used up to 12 characteristics of the neurons voltage output to compare their physiological properties, including resting membrane potential, membrane resistance, rehobase, the occurrence and intensity of post inhibitory response spikes, among others. In order to compare this complex set of physiological and dynamical parameters of jcBNST neurons from rats with a history of prolonged withdrawal and controls, we used the fuzzy K-means clustering algorithm, an unsupervised learning technique derived from a standard K-means algorithm. The goal of cluster analysis is the classification of objects based on similar properties among them and the subdivision into groups or clusters. Among the advantages of the fuzzy clustering algorithm one is that it allows objects to belong to several clusters simultaneously, with different degrees of membership. Our results showed that jcBNST neurons from normal animals displayed a higher degree of physiological diversity than those from dependent animals, meaning that the former subdivided into a greater number of clusters than the latter. Our experiments also showed that long-term neuroadaptive changes induced by drugs of abuse can alter populations of extended amygdala neurons in a way that might remain undetected if evaluating only their gross physiological properties
An automated apparatus for the study of visual discriminations in pigeons.
No full textA fully automated apparatus for the study of visual discriminations in pigeons is described. The apparatus allows the presentation of a single stimulus for successive discriminations and of two or more stimuli at the same time for simultaneous discriminations. It has proven advantageous for comparing successive and simultaneous discriminations in tests of interocular transfer
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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