1,720,987 research outputs found
Expression of TrkB receptors in developing visual cortex is not regulated by light
No full text1. Neurotrophins are very good candidates which relate electrical activity to molecular changes in activity-dependent phenomena. They exert their action through binding to specific tyrosine-kinase receptors: Trk receptors. It is important to consider Trk distribution in order to understand better the role of neurotrophins in the Central Nervous System (CNS). We focused our attention on brain-derived neurotrophic factor (BDNF) Trk receptors (TrkB) during development of the rat visual cortex, since this neurotrophin has been shown to play an important role in visual system development and plasticity. 2. We investigated the full length form of TrkB receptors considering both its total amount and its cellular distribution. To address this issue we used an antibody that recognizes the full length form of TrkB and we used it both in Western blot and immunohistochemistry. 3. We found that the expression of TrkB; receptor increases during development, but that there is no effect on visual experience, since dark-reared animals show the same protein level and pattern of TrkB expression compared to age-matched, normally reared controls
Synergistic effects of brain-derived neurotrophic factor and chondroitinase ABC on retinal fiber sprouting after denervation of the superior colliculus in adult rats
Get PDFDamage to the adult CNS often causes devastating and permanent deficits because of the limited capacity of the brain for anatomical reorganization. The finding that collateral sprouting of uninjured fiber tracts mediates recovery of function prompts the search for experimental strategies that stimulate axonal plasticity after CNS trauma. Here we characterize treatments that promote the sprouting of undamaged retinal afferents into the denervated superior colliculus (SC) after a partial retinal lesion in the adult rat. Delivery of brain-derived neurotrophic factor (BDNF) was performed to enhance the intrinsic potential of retinal ganglion cells to reelongate their axons. Reduction of the neurite growth-inhibitory properties of the adult SC was accomplished via treatment with chondroitinase ABC (C-ABC), which degrades chondroitin sulfate proteoglycans. Retinal axons were labeled via intraocular injections of fluorescently tagged cholera toxin B subunit, and fiber sprouting within the den..
Synaptic plasticity of feedback connections in rat visual cortex
No full textThe issue we want to address in the present paper is to establish whether electrical stimulation of latero medial (LM) area, a secondary visual area in the rat, is able to induce Long Term Potentiation (LTP) and Long Term Depression (LTD) in primary visual cortex (V1). To this aim rat slices containing area V1 and LM were prepared at P23 and P40 and field potentials in layers 2/3 of area V1 were recorded stimulating LM. We showed that it was never possible to induce LTP in area V1, unless bicuculline, a gamma-aminobutyric acid (GABA) receptors blocker, was applied to the slice. In contrast, LTD was normally inducible. Thus, cortical gabaergic circuitry in area V1 controls LTP but not LTD elicited by stimulation of feedback connections from LM. (C) 1999 Published by Elsevier Science B.V. All rights reserved
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
Transcriptomic Studies in Mouse Models of Rett Syndrome: A Review
No full textRett Syndrome (RTT) is a neurological disorder mainly associated with mutations in the X-linked gene coding for the methyl-CpG binding protein 2 (MECP2). To assist in studying MECP2's function, researchers have generated Mecp2 mouse mutants showing that MECP2's product (MeCP2) mostly functions as a transcriptional regulator. During the last two decades, these models have been used to determine the genes that are regulated by MeCP2, slowly dissecting the etiological mechanisms underlying RTT. In the present review, we describe the findings of these transcriptomic studies, and highlight differences between them, and discuss how studies on these genetic models can sharpen our understanding of the human disorder. We conclude that – while there's large variability regarding the number of differentially expressed genes identified – there are overlapping features that inform on the biology of RTT
Environmental enrichment promotes fiber sprouting after deafferentation of the superior colliculus in the adult rat brain
No full textRat visual cortical neurones express TrkA NGF receptor
No full textIn this study we report the expression of TrkA receptor within the rat visual cortex during postnatal development and in adulthood, using a specific monoclonal antibody which recognizes the extracellular domain of TrkA receptor. TrkA was not detected by immunohistochemistry at postnatal day I3 (PI3), i.e. before eye opening. At P22 TrkA was mostly localised in cortical fibre-like processes. At P39 and P90,TrkA-positive neuronal cell bodies in supragranular and infragranular layers were found. Using double immunohistochemistry, labelled cells were identified as intrinsic cholinergic neurones, and as interneurones expressing calbindin and neuropeptide Y. We conclude that TrkA is expressed in visual cortical neurones during postnatal development and in adulthood and that its pattern of expression is developmentally regulated
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
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