1,720,961 research outputs found
Nucleus Accumbens shell and core dopamine responsiveness during operant responding for sucrose: nose poking versus lever pressing
No full textIn our study we investigated by microdialysis the responsiveness of dopamine (DA) transmission in the nucleus accumbens shell and core in rats responding for sucrose using two different operant schedules: nose poking versus lever pressing.
In rats trained to respond for sucrose pellets on nose poking fixed ratio 1 (FR1) schedule, dialysate DA increased in the shell but not in the core during active responding as well as under extinction in the presence of sucrose cues. In rats responding for sucrose on lever pressing FR1 schedule we observed a strengthening of DA transmission both in the shell and in the core.
Non-contingent sucrose presentation and feeding in nose poking and lever pressing FR1 trained animals increased dialysate DA to a similar extent in the shell and in the core.
We can conclude that while non contingent sucrose feeding activates dopamine transmission in the shell and core, response-contingent feeding activates without habituation dopamine transmission selectively in the shell in nose poking FR1 trained rats as a result of the action of sucrose conditioned cues. In lever pressing trained rats during responding for sucrose we found an increase of DA in both areas as a result of the higher effort required to obtain the reward.
These findings can explain most of the discrepancies existing in the literature on the responsiveness of shell and core DA during food self administration
Orexin A administration by lactoferrin- and antitransferrin-modified liposomes potentiate the nucleus accumbens shell dopamine responsiveness to food.
No full textOrexin neurons originate in the hypothalamic region and project to different brain areas. They produce two different neuropeptides: orexin A (Orx A) and orexin B (Orx B) and two receptors for the orexin system has been characterized: OxR1 and OxR2. OxR1 binds orexin A with 30 nM affinity but has much lower affinity for orexin B, whereas OxR2 binds both orexin peptides with similar high affinity.
Several studies reported that orexinergic neurons in the lateral hypothalamus (LH) are involved in motivated behavior for drugs of abuse as well as natural rewards. In particular administration of orexin A has been shown to stimulate food consumption, and orexin signaling in VTA is implicated in intake of high-fat food.
It has been shown that LH orexin neurons project to the ventral tegmental area (VTA) indicating that the VTA is an important site of action for orexin's role in reward processing.
Mesolimbic dopamine (DA) in the nucleus accumbens (NAc) shell is also involved in the rewarding mechanisms of food consumption.
Is there a cooperation between DA and Orx A?
In our study we investigated by brain microdialysis the responsiveness of NAc shell DA transmission in food consumption after intravenous administration of Orx A encapsulated in different targeted and not-targeted stealth liposomes prepared using film hydration method.
Orx A per se produced a later increase of DA in the NAc shell (peaking at 80 min sample) and strengthened the DA responsiveness in this area after sucrose pellets feeding. We registered also an increase of the number of eaten pellets. These effects on DA and on feeding were blocked by intraperitoneally injection of the antagonist of the OxR1 (SB 334867, 30mg/Kg).
We can speculate that the strengthening of DA response during food consumption exerted by Orx A administration could increase the rewarding properties of food and could be one of the mechanisms that underlie food addiction.
These findings could suggest new targets for a new treatment of eating disorders
INTERACTION BETEEW OREXIN-A AND MESOLIMBIC DOPAMINE IN PALATABLE FOOD CONSUMPTION
No full textSeveral studies reported that orexinergic neurons in the lateral hypothalamus (LH) are involved in motivated behavior for drugs of abuse as well as natural rewards. In particular it has been observed that administration of orexin A (OrxA) stimulates food consumption, and orexin signaling in VTA is implicated in the intake of high-fat food. On the other hand in the VTA are located dopaminergic neurons that project to the nucleus accumbens (NAc) shell, an area in which the dopamine (DA) plays a key role in the responsiveness to the rewarding properties of food as well as of drugs of abuse.
The aim of our study was to investigate if there is any cooperation between the OrxA and the DA released in the NAc shell.
We investigated by brain microdialysis the responsiveness of NAc shell DA in food consumption after intravenous administration of OrxA encapsulated in different targeted and not-targeted stealth liposomes.
OrxA per se produced an increase of DA in the NAc shell and strengthened the DA responsiveness in this area to sucrose pellets consumption. OrxA administration also increased the number of eaten pellets. These effects on DA transmission and feeding were affected by the antagonist of the OxR1 (SB 334867).
We can hypothesize that the strengthening of DA response during food consumption exerted by OrxA administration could increase the rewarding properties of food and could be one of the mechanisms that underlie food addiction.
These findings could suggest new targets for a new treatment of eating disorders.
Study supported by Regione Autonoma della Sardegn
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
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
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