1,720,957 research outputs found
Learning and discrimination of multimodal sensorial stimuli before and after hippocampal lesion.
No full textLearning and discrimination of multimodal sensorial stimuli before and after hippocampal lesion.
No full textGIRK1-Mediated Inwardly Rectifying Potassium Current Is a Candidate Mechanism Behind Purkinje Cell Excitability, Plasticity, and Neuromodulation
No full textG-protein-coupled inwardly rectifying potassium (GIRK) channels contribute to the resting membrane potential of many neurons and play an important role in controlling neuronal excitability. Although previous studies have revealed a high expression of GIRK subunits in the cerebellum, their functional role has never been clearly described. Using patch-clamp recordings in mice cerebellar slices, we examined the properties of the GIRK currents in Purkinje cells (PCs) and investigated the effects of a selective agonist of GIRK1-containing channels, ML297 (ML), on PC firing and synaptic plasticity. We demonstrated that GIRK channel activation decreases the PC excitability by inhibiting both sodium and calcium spikes and, in addition, modulates the complex spike response evoked by climbing fiber stimulation. Our results indicate that GIRK channels have also a marked effect on synaptic plasticity of the parallel fiber-PC synapse, as the application of ML297 increased the expression of LTP while preventing LTD. We, therefore, propose that the recruitment of GIRK channels represents a crucial mechanism by which neuromodulators can control synaptic strength and membrane conductance for proper refinement of the neural network involved in memory storage and higher cognitive functions
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
Role of β3-adrenergic receptor in the modulation of synaptic transmission and plasticity in mouse cerebellar cortex
No full textConvergent lines of evidence have recently highlighted β3-adrenoreceptors (ARs) as a potentially critical target in the regulation of nervous and behavioral functions, including memory consolidation, anxiety, and depression. Nevertheless, the role of β3-ARs in the cerebellum has been never investigated. To address this issue, we first examined the effects of pharmacological manipulation of β3-ARs on motor learning in mice. We found that blockade of β3-ARs by SR 59230A impaired the acquisition of the rotarod task with no effect on general locomotion. Since the parallel fiber–Purkinje cell (PF–PC) synapse is considered to be the main cerebellar locus of motor learning, we assessed β3-AR modulatory action on this synapse as well as its expression in cerebellar slices. We demonstrate, for the first time, a strong expression of β3-ARs on Purkinje cell soma and dendrites. In addition, whole-cell patch-clamp recordings revealed that bath application of β3-AR agonist CL316,243 depressed the PF–PC excitatory postsynaptic currents via a postsynaptic mechanism mediated by the PI3K signaling pathway. Application of CL316,243 also interfered with the expression of PF long-term potentiation, whereas SR 59230A prevented the induction of LTD at PF–PC synapse. These results underline the critical role of β3-AR on cerebellar synaptic transmission and plasticity and provide a new mechanism for adrenergic modulation of motor learning
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