1,721,024 research outputs found
Mammalian hippocampal neuronal plasticity under normal and pathological conditions
Full text linkNeuroplasticity is a term that includes all the functional and structural changes within a neural circuit in response to external or internal events, changes at synaptic level, in the morphology, or in the number of cells. These changes are related with functional modifications and have great relevance under physiological conditions and in neuropathology.
The malleability of the nervous system has a central role in shaping the brain during prenatal and early postnatal development, in the childhood, but also in the adulthood, supporting vital functions, such as learning and memory. Therefore, the first part of this PhD thesis is focused on study about the mechanism of physiological plasticity in the hippocampus in relation with network activation induced by common every-day experiences, such as physical activity. Hippocampus, indeed, attracts great attention in the neuroscience research field because it takes part to certain types of learning and memory but also because of its extraordinary degree of neuronal plasticity. In this structure, much of the attention is mainly focused on neuronal plasticity phenomena, such as synaptic Long Term Potentiation (LTP) and adult neurogenesis: this last phenomenon represents a fascinating example of plasticity occurring in a specific hippocampal area called Dentate Gyrus (DG). Here, new granule cells are daily generated and incorporated in the existing network. In the hippocampus, stem/progenitor cell proliferation and newly-generated granule cell integration are affected by numerous stimulus both physiological and pathological. In keeping with this statement, physical exercise represents a pro-neurogenic activity. Our previous findings highlighted that a brief physical activity, and in particular voluntary running, produces short-term effects in very immature newborn granule cells of adult DG. Here, the attention is shifted in the research for possible long-lasting effects of voluntary running on newly-generated granule cells, evaluating morphological and possible functional implications related with this activity, with the purpose of removing part of the shadows upon the possible mechanism of cognitive enhancement widely reported in association with physical exercise.
Additionally, since abnormal plastic adaptation underlies many neural diseases, the second part of this thesis has considered two pathologies, depression and epilepsy, in order to uncover and highlight possible treatments able to influence, or prevent, the aberrant plastic support to these neuropathologies. Concerning depression, the focus was placed on the study of Fibroblast Growth Factor Receptor 1 – 5-hydroxytryptamine 1A (FGFR1-5HT1A) heteroreceptor complex role in depression, which is a receptor-receptor (R-R) interaction of extreme interest since it represents the meeting point between two theories of depression, the serotoninergic and the neurotrophic factor hypotheses. The FGFR1-5HT1A heteroreceptor complex is reported to exist in hippocampus. In addition, combined agonist treatment influences cellular throphism and morphology, suggesting that activation of FGFR1-5HT1A heteroreceptor complex might be related with antidepressant effect of serotonin in the brain and, combined activation of both receptors might result in more rapid and stronger antidepressant action than that found with Selective Serotonin Reuptake Inhibitors (SSRIs). Indeed, an important clinical pursuit in the depression field is the research for fast-acting treatments or molecules able to speed up the effects of the canonical anti-depressive drugs, since commonly available treatments exert their therapeutic action after a delay that last from weeks to months. Thus, the attention has been focused on a first evaluation about the therapeutic potential of combined FGFR1 and 5HT1A agonist treatment, which has been firstly tested on Sprague Dawley (SD) rats, using electrophysiological, molecular and behavioural approaches. Afterward, to evaluate if disturbances of the FGFR1-5HT1A heteroreceptor complex might exist in depression and if the combined treatment with the agonists of the FRGR1 and 5-HT1A could exert antidepressant effects, the attention was moved on Flinders Sensitive Line Rats (FSL), a well-known model of depression. Actually, the potential existence of disturbances in depression at FGFR1-5HT1A heteroreceptor complex level could represent an exciting finding since it might confirm these complexes as valid targets for future therapeutic treatments with possible fast-acting properties. The other pathology investigated in the second part of this PhD thesis is the mesial temporal lobe epilepsy (MTLE), the most common form of localization-related epilepsy, which is characterised by progressive plastic rearrangements that lead to the chronicization of the disease and the aberrant remodelling of the hippocampal network. Treatment able to counteract the chronicization of epilepsy represents an unmet clinical need. Previous findings from our laboratory of physiology suggested a potential and promising role of Vitamin E (as -tocopherol) as antiepileptogenic treatment, which might act through different mechanisms than anti-oxidant one. To validate this assumption, using the kainate rat model of epilepsy, the excitability of hippocampus circuitry, the neuroinflammation markers, neuron cell death and microRNA (miRNAs) expression, have been investigated in adult rat after 15-days of -tocopherol treatment.
Overall, essential cognitive process but also several neuropathologies have a common underlying feature called brain plasticity, which plays a double but opposite role in these different conditions, thus being of huge interest for neuroscience and all human life. Accordingly, managing to manipulate brain plasticity is gaining great attraction for its potential in health and disease. On one hand, it might improve essential features as learning, memory and cognition: indeed, a brief physical activity creates short-term and long-lasting modifications in hippocampus, which could influence future network activity and lead to cognitive enhancement. On the other hand, the research for treatments potentially able to counteract aberrant plastic changes in disease, as those observed in depression or epilepsy, might represent a promising approach aimed to correct the mechanisms behind the pathology and not the symptoms themselves
Petra end Baida:Two adjacent archaeological sites deeply integrated in impressive geomorphologic landscape
No full textLAVORO ACCETTATO DAI REFERE
Petra end Beida (Jordan): Two archaeological sites up to an exploitation of geomorphology related topics for a cultural and touristic development
No full textLavoro accettato dai refere
3D Structure of the northern Marche region, and implications for the active tectonics of the outer Northern Apennines (Italy)
No full textGoing 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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