1,721,004 research outputs found
Modulatory functions of neurotransmitters in the striatum Ach/dopamine/NMDA interactions
No full textThe striatum is viewed as a structure performing fast neurotransmitter-mediated operations through somato-topically organized projections to medium-size spiny neurons. This view is contrasted with another view that depicts the striatum as a site of diffuse modulatory influences mediated by cholinergic interneurons and by dopamine and N-methyl-D-aspartate receptors. These two operational and organizational modes both contribute, through their mutual interaction, to the function of basal ganglia. Detailed knowledge of the neural mechanisms by which such interactions take place and are expressed into behaviour, can provide new insight into the physiopathology and new clues for therapy of disorders of basal ganglia
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
Art. 3. Parità di condizioni fra i detenuti e gli internati
No full textLo scritto analizza la disposizione dell'ordinamento penitenziario dedicata alla parità di trattamento dei detenuti.The paper analyses the provisions of the penitentiary system dedicated to equal treatment of prisoner
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
Role of the parafascicular thalamic nucleus and N-methyl-D-aspartate transmission in the D-1-dependent control of in vivo acetylcholine release in rat striatum
No full textWe investigated the involvement of glutamatergic neurotransmission in the modulation of D-1 receptor-mediated stimulation of acetylcholine outflow in dorsal striatum in freely moving rats, and the relative roles of the thalamostriatal and corticostriatal pathways in this regulation using in vivo microdialysis. The selective n-methyl-D-aspartate non-competitive antagonist dizocilpine maleate (0.1 mg/kg i.p.), but not the kainate/quisqualate receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione (3 mu g per side i.c.v.), completely prevented the rise in striatal extracellular acetylcholine elicited by maximal effective doses of the full D-1 agonist SKF 82958 (3 mg/kg s.c.) and of the dopamine releaser d-amphetamine (2 mg/kg s.c.). Acute bilateral electrolytic lesions of the parafascicular nucleus of the thalamus prevented the stimulation of striatal acetylcholine output by SKF 82958 and d-amphetamine but only slightly reduced basal acetylcholine release. In contrast acute interruption of the corticostriatal pathway did not alter the effect of the two dopaminergic drugs although it markedly reduced basal striatal acetylcholine release. Lesions of the parafascicular thalamic nucleus, or a low dose of dizocilpine maleate (0.1 mg/kg i.p.), also prevented the acetylcholine-increasing effect of the neuroleptic remoxipride (10 mg/kg s.c.), an effect known to be D-1 receptor dependent. The results suggest that striatal projections arising from the parafascicular thalamic nucleus and utilizing N-methyl-D-aspartate receptors play a critical role in the D-1-mediated stimulation of acetylcholine release in dorsal striata
ENDOGENOUS DOPAMINE FACILITATES STRIATAL IN VIVO ACETYLCHOLINE-RELEASE BY ACTING ON D(1)-RECEPTORS LOCALIZED IN THE STRIATUM
No full textIntrastriatal application of the D1 antagonist SCH 23390 by two procedures, reverse dialysis (20-mu-M) and local injection (0.45 nmol per striatum), elicited a reduction in acetylcholine (ACh) release superimposable on that induced by systemic administration. The novel selective D1 antagonist SCH 39166 produced a similar decreasing effect on striatal ACh release on local injection (0.45 nmol per striatum). On the other hand, local application of SCH 23390 into the frontal cortices (0.45 nmol per side) failed to alter striatal ACh overflow, indicating that the drug does not diffuse out of its injection site to any significant extent. The dopamine release inducer d-amphetamine (2 mg/kg s.c.) and the dopamine uptake inhibitor cocaine raised ACh release like the D1 agonists. These effects were completely blocked by 10-mu-M SCH 23390 applied by reverse dialysis. The results suggest that D1 receptors regulating ACh release are located in the striatum
Surgical anaesthesia with pentobarbital prevents the effect of local SCH 23390 on rat striatal acetylcholine release in a strain-dependent manner.
No full textThis study was performed in order to clarify existing discrepancies about the ability of the D1 antagonist SCH 23390 to reduce striatal acetyicholine (ACh) release after intrastriatal application by reverse dialysis. The possibility that negative findings were related to the use of pentobarbital rather than Equithesin as surgical anaesthesia for implanting microdialysis probes, and of Wistar rather than Sprague-Dawley rats, was tested. SCH 23390, applied by reverse dialysis at the concentration of 24μM, although able to reduce dialysate ACh in male Wistar rats implanted under Equithesin anaesthesia, failed to do so in rats of the same strain implanted 24h or 3 days earlier under pentobarbital anaesthesia. In male Sprague-Dawley rats, local SCH 23390 (24μM) reduced striatal dialysate ACh, both in rats implanted under Equithesin as well as in rats implanted under pentobarbital anaesthesia. Systemic SCH 23390 (0.3mg/kg s.c.) reduced dialysate A Ch both in Wistar and in Sprague-Dawley rats implanted under pentobarbital anaesthesia, but was more effective in the Sprague-Dawley strain. These observations, although consistent with a striatal localization of D1-receptors controlling ACh release, can be explained as being the result of a strain-dependent barbiturate-induced inactivation of D1-mediated control of ACh transmission, which is potentiated by the local changes induced by microdialysis probe implan
DOPAMINE DEPLETION PREFERENTIALLY IMPAIRS D1-RECEPTOR OVER D2-RECEPTOR REGULATION OF STRIATAL INVIVO ACETYLCHOLINE-RELEASE
No full textThe roles of D2 and D1 dopaminergic receptors on the regulation of striatal acetylcholine (ACh) release in vivo were examined for a period of 120 min after acute (2 h) or prolonged (16 h) depletion of brain dopamine (DA) by alpha-methyl-p-tyrosine. The reduction of DA transmission did not affect basal ACh output after 2 h but markedly lowered ACh release by 16 h (50%). Acute alpha-methyl-p-tyrosine pretreatment prevented the reduction of ACh release by the D1 antagonist SCH 23390 and its increase by the D2 antagonist, remoxipride, consistent with a drastic reduction of DA transmission at both DA receptors. However, 16 h after alpha-methyl-p-tyrosine, the effect of remoxipride on ACh release was restored, but SCH 23390 still had no effect, suggesting that the D2 inhibitory tone on ACh release had recovered, whereas the reduction of the D1 facilitatory influence persisted. The D1 facilitatory control of ACh neurotransmission thus appears to be more sensitive than the D2 inhibitory control to a reduction in DA transmission. The new model of DA-ACh interaction resulting from these data casts fresh light on the relationship between changes in DA transmission and extrapyramidal motor function
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