1,720,995 research outputs found
Camillo Golgi, Sullafina anatomia degli organi centrali del sistema nervoso. A cura di Alberto Oliverio (Firenze : Giunti, 1995)
No full textCamillo Golgi, Sullafina anatomia degli organi centrali del sistema nervoso. A cura di Alberto Oliverio (Firenze : Giunti, 1995). In: Revue d'histoire des sciences, tome 52, n°3-4, 1999. Mathématique et logique chez Bolzano. pp. 518-520
Camillo Golgi, Sullafina anatomia degli organi centrali del sistema nervoso. A cura di Alberto Oliverio (Firenze : Giunti, 1995)
No full textCamillo Golgi, Sullafina anatomia degli organi centrali del sistema nervoso. A cura di Alberto Oliverio (Firenze : Giunti, 1995). In: Revue d'histoire des sciences, tome 52, n°3-4, 1999. Mathématique et logique chez Bolzano. pp. 518-520
Spatial memory, plasticity and nucleus accumbens
No full textResearch on the function of the nucleus accumbens, the most ventral component of the striatal complex, has traditionally focused on locomotor activity, reward, motivation and addiction. However, based on the existence of projections to the nucleus accumbens from the allocortical regions involved in spatial navigation, it has been suggested that this structure plays a role in spatial learning and memory. Lesion and neuropharmacological studies confirm this view, also revealing the complex dynamics of the receptors involved in these processes. Moreover, the effects of post-training intra-nucleus accumbens drug administrations demonstrate the necessity of off-line neural activity within this structure in order to consolidate spatial memory. Blockade of molecular processes implicated in synaptic plasticity, such as cAMP response element-binding protein (CREB)-induced transcription or extracellular matrix remodeling, provides further experimental support to this hypothesis. These observations imply that experience-dependent synaptic plasticity responsible for long-term stabilization of spatial information might occur within the nucleus accumbens, similarly to what has been observed in the hippocampus. This suggests that a comprehensive understanding of spatial memory processing should be viewed in the context of a wider neural circuit
Impairing effect of amphetamine and concomitant ionotropic glutamate receptors blockade in the ventral striatum on spatial learning in mice
No full textAccumulating evidence supports the involvement of the ventral striatum (VS) in spatial information processing. The multiple cortical glutamatergic and mesolimbic dopaminergic (DAergic) afferences on the same neurons in the ventral striatum provide the neuroanatomical substrate for glutamate and dopamine functional interaction. However, there is little evidence in the literature on how this interaction affects the ability to encode spatial information. First, we evaluated the effect of intra-VS bilateral infusion of different doses of amphetamine (0.3, 0.75, and 1.5 mu g/side) on the ability to detect spatial novelty in mice. Next, we examined the impact produced on the same abilities by intra-VS infusion of ineffective doses of amphetamine (0.3 mu g/side) in association with N-methyl-d-aspartate (NMDA) (3.125 ng/side) or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) (0.25 ng/side) receptor antagonist. The results show that infusion of amphetamine impairs detection of spatial novelty, affecting also exploratory activity and marginally the detection of nonspatial novelty. In contrast, an association of subthreshold doses of amphetamine with NMDA or AMPA receptor antagonists exerted a selective effect on reactivity to a spatial change. These findings demonstrate that enhanced DAergic activity in the VS enhances glutamate receptor antagonist-induced impairment in learning and 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
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