1,721,007 research outputs found
P/Q-type calcium-channel blockade in the periaqueductal gray facilitates trigeminal nociception: a functional genetic link for migraine?
No full textThe discovery of mis-sense mutations in the alpha1A subunit of the P/Q-type calcium channel in patients with familial hemiplegic migraine indicates the potential involvement of dysfunctional ion channels in migraine. The periaqueductal gray (PAG) region of the brainstem modulates craniovascular nociception and, through its role in the descending pain modulation system, may contribute to migraine pathophysiology. In this study we sought to investigate the possible link between the genetic mutations found in migraineurs and the PAG as a modulator of craniovascular nociception. We microinjected the P/Q-type calcium-channel blocker omega-agatoxin IVA into the rat ventrolateral PAG (vlPAG). We examined its effect on the nociceptive transmission of second-order neurons recorded in the trigeminal nucleus caudalis and activated by stimulation of the parietal dura mater. After injection of agatoxin into the vlPAG (n = 20) responses to dural stimulation were facilitated by 143% (p < 0.0001) for Adelta-fiber activity and 180% for C-fiber activity (p < 0.05). Similarly, spontaneous background activity increased by 163% (p < 0.0001). These results demonstrate that P/Q-type calcium channels in the PAG play a role in modulating trigeminal nociception and suggest a role for dysfunctional P/Q-type calcium channels in migraine pathophysiology.<br/
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
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
Functional Anatomy, Development, and Pathology of the Hippocampus
No full textThe hippocampal formation is comprised of a group of cortical regions, including the dentate gyrus, hippocampus, subiculum, presubiculum, parasubiculum, and entorhinal cortex. The hippocampal formation plays a central role in the brain network essential for memory function. Paradoxically, the hippocampus is also the brain structure most sensitive to hypoxic-ischaemic episodes. In addition, abnormalities in hippocampal structure and functions have been reported in a number of neuropathological and neurodevelopmental disorders. This chapter provides a basic description of the structural organization of the primate hippocampal formation. This chapter also discusses recent findings regarding its normal postnatal development, which provide an essential framework to consider the aetiologies of different neurodevelopmental disorders affecting hippocampal structure and function. In particular, a developmental decrease in astrocytic processes and functions may be the critical factor underlying the selective vulnerability of CA1 to hypoxic-ischaemic episodes in adulthood. It also provides an explanation for the relative resistance of this brain structure to hypoxia in the perinatal period, especially during the birth process. In contrast, a major benefit that derives from decreased astrocytic coverage is the regulation of synaptic efficacy leading to an increase in synaptic selectivity advantageous for learning. In addition, the relatively high astrocytic coverage of newborn synapses might also play a central role in the generation of febrile seizures. Finally different periods of postnatal development during which pathogenic factors might impact the structural and functional maturation of distinct hippocampal regions were identified, as is observed in autism, schizophrenia, epilepsy, and Down syndrome
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
Gedächtniskonsolidierung im Schlaf bei Patienten mit Schizophrenie und gesunden Kontrollen: Gibt es Unterschiede ob der Abruf angekündigt wurde oder nicht?
No full textZu den schwerwiegenden Symptomen bei Patienten mit Schizophrenie gehören Halluzinationen und Wahnvorstellungen, aber auch Defizite im deklarativen Gedächtnis. In früheren Studien konnte man Zusammenhänge zwischen verändertem Schlaf und verminderter Gedächtnisleistung bei Patienten mit Schizophrenie fest-stellen. Weiterhin fand man heraus, dass Gedächtnisinhalte im Schlaf nicht gleich-wertig gefestigt werden, sondern dass das Gehirn aufgrund seiner begrenzten Kapazität eine Hierarchie entwickelt und vornehmlich speichert, was wichtig erscheint. Ziel der Studie war es den Einfluss von Zukunftsrelevanz der Informationen auf die Speicherung deklarativer Gedächtnisinhalte bei Patienten mit Schizophrenie zu untersuchen. Hierfür verglichen wir eine Gruppe von Patienten mit Schizophrenie (N=18) mit einer gesunden Kontrollgruppe (N=24). Die Probanden erlernten assoziierte Wort-paare und verbrachten die anschließende Nacht im Schlaflabor. Einem Teil der Probanden wurde vor dem Test mitgeteilt, dass die Wortpaare am nächsten Morgen erneut abgefragt werden. Die anderen Probanden wussten nichts von dem erneuten Abfragen der Wortpaare am nächsten Morgen. In den Ergebnissen konnten wir ein Defizit im deklarativen Gedächtnis von Patienten mit Schizophrenie bestätigen, sowohl hinsichtlich der freien Abrufleistung am Morgen, als auch hinsichtlich der schlafbezogenen Gedächtniskonsolidierung. Bei den gesunden Kontrollen zeigte sich eine signifikant positive Korrelation zwi-schen der Gedächtnisleistung und der Tiefschlaflänge. Dieser Zusammenhang fand sich bei den Patienten nicht. Dies kann man auf einen unterschiedlichen Effekt der applizierten Medikamente auf den Tiefschlaf zurückführen. Die vorherige Ankündigung des Abrufs hatte, weder bei den Gesunden noch bei den Patienten, keinen Einfluss auf die Gedächtnistestung. Dieser Befund bedarf weiteren Untersuchungen inwieweit andere Faktoren, wie z.B. Emotionalität oder Cortisol-Spiegel, Einfluss auf die Festigung von Gedächtnisinhalten haben und wie deren einzelne Wichtung zueinander ist
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