1,721,047 research outputs found
Properties and role of Ih in the pacing of subthreshold oscillations in entorhinal cortex layer II neurons
No full textProcessing of analogy in the thalamocortical circuit
No full textThe corticothalamic feedback and the thalamic reticular nucleus have gained
much attention lately because of their integrative and modulatory functions.
A previous study by the author suggested that
this circuitry can process analogies (i.e., the {\em analogy hypothesis}).
In this paper, the proposed model was implemented as a network of leaky
integrate-and-fire neurons to test the {\em analogy hypothesis}.
The previous proposal required specific delay and
temporal dynamics, and the implemented network tuned
accordingly functioned as predicted. Furthermore, these specific
conditions turn out to be consistent with experimental data, suggesting
that a further investigation of the thalamocortical circuit within the {\em
analogical framework} may be worthwhile
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
Dynamics among overlapping memory representations in the hippocampus at long timescales
Full text linkThe hippocampus plays a central role in episodic memory and spatial navigation. The activity of individual neurons and ensembles of cells encodes location within an environment, the spatial context, and non-spatial behavioral task demands, creating unique codes for these features. The hippocampus plays a role both during the initial encoding of memory representations, and also at extended intervals in tasks which require flexible retrieval or self-localization. While behavior and memory can be stable for long periods of time, many studies have shown that their neural basis is more dynamic than expected. In the studies presented here, I used single-photon calcium imaging in freely behaving mice to track hippocampal single-unit activity over many recording sessions to test how circuit instability interacts with ongoing behavioral demands.
In the first study, I asked whether the representation of multiple task demands remained stable alongside an animal’s behavior. Previous work has indicated that hippocampal activity will change as an animal’s performance in a task improves. Additionally, drift, the inactivation and replacement of neuron membership within the active population, may affect neurons that code for different aspects of a task at different rates. I tested this hypothesis by recording hippocampal activity in an alternation task which animals performed stably for multiple weeks. I found that the population code separating each task dimension was highly stable in spite of cell turn over, but that the distribution of task dimensions encoded by single neurons changed as a function of time. This change in distribution of task dimensions encoded by single neurons was not driven by different levels of stability among the different coding populations, as indicated by previous reports, but instead was driven by changing rates with which newly active neurons encoded task dimensions.
In the second study, I looked at how new learning affected a previously-encoded task representation. Mice performed two different tasks in a plus-shaped maze in the sequence A-B-A over a nine-day sequence. One group performed the entire sequence on a single maze, while another group performed the second rule on a second maze. This allowed me to test the hypothesis that new learning in a single environment would cause greater change in the hippocampal representation for that environment than can be accounted for alone by time between recordings. This hypothesis is confirmed by multiple measures of single unit activity, and in the population code.
Together, these results demonstrate that the instability observed in long term patterns of neuronal activity does not impair behavior, and that it may have a role in the ongoing refinement of the organization of hippocampal memory representations
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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