1,721,012 research outputs found
Targeting the food reward system in preclinical models for eating disorders
No full textEating disorders, such as anorexia nervosa (AN) and binge eating disorder (BED), pose a significant health burden, yet current treatment options fail to reach and cure all patients. Furthermore, there is still much to be discovered about the underlying pathophysiology of eating disorders, knowledge crucial for developing more effective, biology-driven medications. Given the abnormal processing of food rewards in both AN and BED, this thesis aimed to explore potential targets within the food reward system in these disorders.
In Chapter 2, we investigated the impact of different doses of olanzapine in the rat ABA model. Additionally, we explored intranasal administration as a rapid and effective delivery method for olanzapine in the ABA model. We found that olanzapine, both systemic and intranasal administration, decreased running wheel activity in the ABA model in rats. As intranasal administration mainly reduced running in the first hours after administration, we recommend further exploration of this approach in patients with AN.
The microbiome is a potential future treatment for AN as alterations in microbiome composition are found in these patients. Whether these microbiome alterations also contribute to AN-related symptoms remains uncertain. In Chapter 3, we transplanted the microbiota of patients with AN in rats before they underwent the ABA model. We demonstrated that fecal microbiota transplantation from patients with AN did not contribute to weight loss or changes in activity, although limited microbiota successfully colonized the rat's gut. However, the only antibiotic-treated group decreased survival, body weight, and body temperature.
In Chapter 4, we studied whether AN microbiota altered flexible value-based decision-making in the reversal learning task and related dopamine signaling and anxiety. Microbiota fecal transplantation did not alter flexible learning, ventral tegmental area (VTA) dopamine signaling and anxiety, although the transplantation efficiency was low. Furthermore, the antibiotic treatment decreased task engagement acutely but did not alter flexible learning or VTA dopamine activity.
In Chapter 5, we investigated semaglutide’s effect on VTA dopaminergic neuron signaling during food-predicting cues and sucrose reward consumption. We found that the semaglutide decreased food-seeking behaviors in the sucrose conditioning task. At the same time, the VTA dopamine activity increased during sucrose consumption but was unchanged during the food-predictive cue.
In Chapter 6, we explored the influence of ghrelin on VTA dopamine neuron signaling during a reward-seeking task. We discovered that ghrelin increased VTA dopamine neuron activity in response to a food-predictive cue and increased food-seeking behaviors. Additionally, prefeeding food-restricted mice with chow lowered endogenous ghrelin levels, decreased food-seeking behaviors and reduced VTA dopamine neuron activity during cue presentation.
Besides dopamine neurons in the VTA, there is also a proportion of gamma-aminobutyric acid (GABA) neurons. The VTA GABA-neurons too are suggested to play a role in cue and reward signaling. In Amendment 1, we observed changes in VTA GABA neuron activity during the food-predictive cue and reward collection. Interestingly, the VTA neuronal activity during the food-predictive cue depended on the reward collection following the cue, both for the dopamine and GABA neurons
By force of habit: On the formation and maintenance of goal-directed habits
No full textThe aim of this thesis was to examine how goal-directed habits are formed and established. Specifically, the focus was on the cognitive mechanism underlying habits and the role of habits in guiding goal-directed behavior. In daily life we perform all kinds of behaviors to attain specific goals in absence of conscious awareness. People are able to perform rather complex behaviors (e.g., getting to work, socializing with friends) in the absence of explicit intent as a result of frequently engaging in them. In Chapter two, three studies examined the cognitive processes underlying the formation of goal-directed habits in a multiple means context. Habits are formed through the repeated retrieval and selection of a specific means for goal attainment. Repeated retrieval of target means upon goal activation was expected to result in inhibition of competing means for the same goal to prevent these latter means from interfering. In all studies, participants studied goal-means combinations and subsequently practiced the retrieval of certain means to attain the goals in a retrieval-paradigm. It was found that competing means were inhibited after repeated retrieval of the target means. Furthermore, it was demonstrated that inhibition occurred in the absence of explicit intent or instructions to suppress the competing means. In Chapter three, two studies examined whether the formation of intentions to pursue a goal in a non-habitual manner causes inhibited access to habitual means to attain that goal. An idiosyncratic approach was used to assess personalized goal-means relations. The results indicated that the formation of an intention to use non-habitual means inhibited the representations of the habitual means in order to prevent habitual intrusion. However, the intention to use habitual means did not cause inhibited access to non-habitual means. In Chapter four, the role of habit and intention in the prediction of future behavior was examined by analyzing that past behavior frequency moderates the intention-behavior relationship to the extent that the context in which the behavior was performed is stable. In two correlational studies it was found that intentions guided future behavior when habits were weak (low frequency or unstable context), while this was not the case when habits were strong (high frequency and stable context). A third exploratory study suggested that, if habitual goal-directed behavior is automatically activated by the context, mental accessibility of the behavior moderates the intention-behavior relation in a similar way. To summarize, the research in this thesis emphasizes the importance of two factors underlying habits that so far have almost not been considered: the influence of inhibitory processes and the role of context stability. The implications of these findings as well as the possible ways to influence habits and the possible difficulties are discussed in the final chapter of this thesis
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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