1,720,968 research outputs found
Selective immunolesioning of cholinergic neurons in nucleus basalis magnocellularis impairs prepulse inhibition of acoustic startle
No full textInformation processing and attentional abnormalities are prominent in neuro psychiatric disorders. Since the cholinergic neurons located in the nucleus basalis magnocellularis have been shown to be involved in attentional performance and information processing, recent efforts to analyze the significance of the basal forebrain in the context of schizophrenia have focused on this nucleus and its projections to the cerebral cortex. We report here that bilateral selective immunolesioning of the cholinergic neurons in the nucleus basalis magnocellularis is followed by significant deficits in sensorimotor gating measured by prepulse inhibition of the startle reflex in adult rats. This behavioral approach is used in both humans and rodents and has been proposed as a valuable model contributing to the understanding of the neurobiological substrates of schizophrenia. The disruption of prepulse inhibition persisted over repeated testing. The selective lesions were induced by bilateral intraparenchymal infusions of 192 IgG saporin at a concentration having minimal diffusion into adjacent nuclei of the basal forebrain. The infusions were followed by extensive loss of choline acetyltransferase-immunopositive neurons. Our results show that the cholinergic neurons of the nucleus basalis magnocellularis represent a critical station of the startle gating circuitry and suggest that dysfunction of these neurons may result in impaired sensorimotor gating characteristic of schizophrenia. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved
Rivastigmine antagonizes deficits in prepulse inhibition induced by selective immunolesioning of cholinergic neurons in nucleus basalis magnocellularis
No full textImpairments of cortical cholinergic inputs from the nucleus basalis magnocellularis fundamentally alter information processing and attentional function, thereby advancing the severity of psychopathology in major neuropsychiatric disorders. It was previously shown in adult rats that bilateral 192 IgG saporin-induced selective immunolesioning of the cholinergic neurons in the nucleus basalis produces pronounced and long-lasting deficits in sensorimotor gating measured by prepulse inhibition of the startle reflex. This behavioral paradigm is considered a valid model of sensorimotor gating deficits in the psychotic spectrum and efforts to analyze the significance of the cholinergic basal forebrain in this context are of great interest. In the present study the predictive value of the selective cholinergic immunolesioning model was tested by examining the ability of the cholinesterase inhibitor rivastigmine to restore prepulse inhibition in immunolesioned rats. We report here a pronounced restoring effect of acute (0.75 or 1.5 mg/kg s.c.) as well as repeated (0.75 mg/kg s.c. b.i.d., for 10 days) treatment with rivastigmine in this model of disrupted prepulse inhibition. Intra-nucleus basalis magnocellularis infusions of 192 IgG saporin resulted in extensive loss of basal-cortical cholinergic neurons as shown by the marked decrease in basal telencephalic choline acetyltransferase immunopositive neurons and cortical choline acetyltransferase activity. In this condition, rivastigmine was found to significantly increase cortical acetylcholine extracellular levels in lesioned animals measured by in vivo microdialysis. Taken together, our results strengthen the proposal that the nucleus basalis represents a critical station of the startle gating circuitry. In addition, our findings strongly indicate that even after dramatic decrease of cholinergic neurons, inhibition of acetylcholinesterase restores the cholinergic synaptic function to a point approaching normalization of experimentally induced psychopathology
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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