1,721,037 research outputs found
Selective immunolesioning of the basal forebrain cholinergic system disrupts short-term memory in rats.
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Survival, differentiation, and connectivity of ventral mesencephalic dopamine neurons following transplantation
No full textThe reconstruction of midbrain dopamine (DA) circuitry through intracerebral transplantation of new DA neurons contained in embryonic ventral mesencephalon (VM) is a promising therapeutic approach for Parkinson's disease (PD). Although some of the early open-label trials have provided proof-of-principal that VM grafts can provide sustained improvement of motor function in some patients, subsequent trials showed that the functional response can be highly variable. This chapter reviews an extensive body of basic and clinical research on the survival, differentiation, and connectivity of DA neurons in VM grafts, and also looks at how these parameters are affected by certain host- and donor-specific variables. We also review how technical advances in the tools available to study the integration of grafted DA neurons, such as transgenic reporter mice, have made significant contributions to our understanding of the capacity of different DA neuronal subtypes for target-directed growth and innervation of appropriate host brain structures. Our established and on-going understanding of the capacity of grafted DA neurons to structurally and functionally integrate following transplantation forms an important basis for the refinement and optimization of VM grafting procedures, and also the development of new procedures based on the use of stem cells
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
The changing face of perceptual rivalry
No full textFunctional brain-imaging studies of house-face binocular rivalry and Rubin's vase-faces illusion have consistently reported face perception-dependent activity in the right fusiform gyrus. Here we use Rubin's illusion and report that activation of the left hemisphere by caloric vestibular stimulation increases the predominance of the faces percept in a substantial number of test subjects. While partially supporting the brain-imaging lateralization reports, our findings also challenge these studies by suggesting that neural mechanisms of Rubin's illusion cannot be limited to extrastriate perception-dependent processing. In accordance with our previously proposed interhemispheric switch model, the present findings support the notion that perceptual rivalry engages high-level cortical structures that mediate unihemispheric attentional selection
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
Transplantation of reprogrammed neurons for improved recovery after stroke
No full textSomatic cells such as fibroblasts, reprogrammed to induced pluripotent stem cells, can be used to generate neural stem/progenitor cells or neuroblasts for transplantation. In this review, we summarize recent studies demonstrating that when grafted intracerebrally in animal models of stroke, reprogrammed neurons improve function, probably by several different mechanisms, e.g., trophic actions, modulation of inflammation, promotion of angiogenesis, cellular and synaptic plasticity, and neuroprotection. In our own work, we have shown that human skin-derived reprogrammed neurons, fated to cortical progeny, integrate in stroke-injured neuronal network and form functional afferent synapses with host neurons, responding to peripheral sensory stimulation. However, whether neuronal replacement plays a role for the improvement of sensory, motor, and cognitive deficits after transplantation of reprogrammed neurons is still unclear. We conclude that further preclinical studies are needed to understand the therapeutic potential of grafted reprogrammed neurons and to define a road map for their clinical translation in stroke
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
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