1,721,060 research outputs found
Transcranial magnetic stimulation: Emerging biomarkers and novel therapeutics in Alzheimer's disease
No full textAlzheimer's disease (AD) is one of the most devastating conditions affecting elderly in Western World. Unfortunately, there are no effective treatments, and patients diagnosed with AD face an uncertain future, caused by the current inability to predict the course of the disease. This is mainly due to the poor comprehension of AD pathophysiology and of patients' clinical heterogeneity. In recent years, several evidences supported the concept that loss of synaptic density could be an early event and precede neuronal degeneration, suggesting that the impairment of synaptic transmission should play a key role in the pathogenesis of different forms of dementia, including AD, frontotemporal dementia and Lewy body dementia. Despite this emerging background it has not been possible to quantify synaptic functioning (or dysfunction) directly in vivo in AD patients. Transcranial magnetic stimulation (TMS) has been recently introduced as a novel approach able to identify the early signatures of synaptic dysfunction characterizing the different forms of AD. We review the novel emerging neurophysiological signatures of AD and how this information may be used as biomarkers for differential diagnosis, disease progression and response to therapy. Finally, we also consider novel therapeutic approaches based on the clinical use of repetitive TMS
The neurobiological foundation of effective repetitive transcranial magnetic brain stimulation in Alzheimer's disease
No full textNoninvasive brain stimulation (NIBS) techniques, such as repetitive transcranial magnetic stimulation (rTMS), are promising candidate therapeutics for Alzheimer's disease (AD). We review the evidence supporting the fundamental mechanisms of action of rTMS treatments in AD. rTMS exerts profound effects at different neurobiological and systems neurophysiological levels. By engaging distinct pre- and postsynaptic structures within the stimulated neural network, it directly or indirectly influences various cellular and molecular components. In AD, rTMS influences synaptic plasticity, inducing lasting structural changes and broad reorganization of functional and structural connectivity at the macroscale level. Importantly, it modulates neurotransmitter circuits characteristically disrupted in AD and restores the excitation/inhibition balance by targeting glutamatergic and γ-aminobutyric acid (GABA)ergic pathways. Moreover, rTMS increases neurotrophic factors, counteracts amyloid and tau accumulation, and mitigates neuroinflammation by reducing microglial activation and pro-inflammatory cytokines release. Therefore, maturing preclinical evidence could guide future precision medicine therapeutic strategies based on personalized NIBS in AD patients. Highlights: Noninvasive brain stimulation (NIBS) techniques, such as repetitive transcranial magnetic stimulation (rTMS), are promising candidate therapeutics for Alzheimer's disease (AD). rTMS modulates neuroplasticity, neurotransmission, and neuroinflammation. Preclinical research shows disease-specific neurobiological effects of rTMS in AD. Promising data from AD patients suggest the translatability of animal model results. Preclinical data may guide precision medicine strategies through personalized NIBS
Editorial (Thematic Issue: Old Facts and New Perspectives to Face Alzheimer's Dementia. Focus on Non Neuronal Participants to Neurodegeneration)
No full textIs dopamine involved in Alzheimer's disease?
Full text linkAlzheimer's Disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline and dementia. Recent advances indicate that AD pathogenesis appears more complex than its mere neuropathology. Changes in synaptic plasticity, neuronal disarray and cell death are pathways commonly recognized as pathogenic mechanisms of AD. It is thought that the altered metabolism of certain membrane proteins may lead to the production of amyloid (Aβ) oligomers that are characterized by an highly toxic effect on neurotransmission pathways, such as those mediated by Acetylcholine. The interaction of Aβ oligomers with these neurotansmitters systems would in turn induce cell dysfunction, neurotransmitters signaling imbalance and finally lead to the appearance of neurological signs. In this perspective, it is still debated how and if these mechanisms may also engage the dopaminergic system in AD. Recent experimental work revealed that the dopaminergic system may well be involved in the occurrence of cognitive decline, often being predictive of rapidly progressive forms of AD. However, a clear idea on the role of the dopamine system in AD is still missing. Here we review the more recent evidences supporting the notion that the dopaminergic dysfunction has a pathogenic role in cognitive decline symptoms of AD
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
LTP-like cortical plasticity is associated with verbal memory impairment in Alzheimer's disease patients
No full textAlzheimer's disease (AD) is characterized by a primary impairment of long-term declarative memory caused by deposition of misfolded protein aggregates. Experimental studies showed that AD neuropathological alterations impair synaptic plasticity and memory performance. Transcranial Magnetic Stimulation protocols have been recently introduced to investigate altered mechanisms of cortical plasticity in AD patients
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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