1,720,958 research outputs found
Sign- versus goal trackers, top down control of attention, and underlying cholinergic mechanisms
No full textThe propensity to attribute incentive salience to reward cues has been hypothesized to indicate vulnerability for addiction-like behavior. Evidence in support of this hypothesis has been obtained from experiments studying animals which, using a Pavlovian conditioned approach test, were categorized as ‘sign-trackers’ (ST). In contrast to ST, ‘goal-trackers’ (GT) do not readily attribute incentive salience to reward cues and are less vulnerable for developing addiction-like behavior. Our research is guided by the hypothesis that ST, when compared with GT, exhibit lower levels of cognitive control of attention, thereby fostering behaviors that interfere with (sustained) attentional performance. Furthermore, as cholinergic modulation of prefrontal circuitry serves as a top-down signal for attention, we hypothesized that attentional performance-associated increases in prefrontal cholinergic neurotransmission are lower in ST than GT. ST and GT were trained and extensively practiced the Sustained Attention Task (SAT). This task consists of signal and non-signal trials and animals are rewarded for hits and correct rejections, respectively, while misses and false alarms trigger the inter-trial interval but have no further scheduled consequences. Asymptotic SAT performance of ST was characterized by lower hit rates when compared with GT. ST more frequently disengaged from orienting toward the intelligence panel, thereby missing signals. Because non-signal trial responding appears to represent the default response mode for all animals, limitations in the ability to sustain attention toward the signal source did not result in lower rates of correct rejections. SAT-associated increases in cholinergic neurotransmission, assessed by using microdialysis, were significantly lower in ST. Because this tonic component of cholinergic neurotransmission modulates prefrontal circuitry via alpha4beta2* nicotinic acetylcholine receptors (nAChRs), we also tested the hypothesis that blocking these receptors in GT disrupts SAT performance. Systemic administration of the relatively beta2*-selective nAChR antagonist dihydro-beta-erythroidine (5.0 mg/kg; i.p.) selectively reduced the hit rate in GT. Collectively, these findings indicate a limited capacity of ST to sustain attention and suppress competing behaviors. This is a key cognitive trait in individuals vulnerable for addiction, in part because it rapidly exhausts the capacity for filtering drug cues and for attending to alternative task cues and engaging in alternative behavior
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
Cholinergic control over attention in rats prone to attribute incentive salience to reward cues
No full textSome rats [sign-trackers (STs)] are especially prone to attribute incentive salience to reward cues, relative to others [goal-trackers (GTs)]. Thus, reward cues are more likely to promote maladaptive reward-seeking behavior in STs than GTs. Here, we asked whether STs and GTs differ on another trait that can contribute to poor restraint over behavior evoked by reward cues. We report that, relative to GTs, STs have poor control over attentional performance, due in part to insufficient cholinergic stimulation of cortical circuitry. We found that, relative to GTs, STs showed poor performance on a sustained attention task (SAT). Furthermore, their performance fluctuated rapidly between periods of good to near-chance performance. This finding was reproduced using a separate cohort of rats. As demonstrated earlier, performance on the SAT was associated with increases in extracellular levels of cortical acetylcholine (ACh); however, SAT performance-associated increases in ACh levels were significantly attenuated in STs relative to GTs. Consistent with the view that the modulatory effects of ACh involve stimulation of α4β2* nicotinic ACh receptors (nAChRs), systemic administration of the partial nAChR agonist ABT-089 improved SAT performance in STs and abolished the difference between SAT-associated ACh levels in STs and GTs. Neither the nonselective nAChR agonist nicotine nor the psychostimulant amphetamine improved SAT performance. These findings suggest that individuals who have a propensity to attribute high-incentive salience to reward cues also exhibit relatively poor attentional control. A combination of these traits may render individuals especially vulnerable to disorders, such as obesity and addiction
Poor and Unstable Sustained Attentional Performance in Sign-Trackers: An Animal Model of Poor Top Down Cognitive Control of Attention
No full textPoor and Unstable Sustained Attentional Performance in Sign-Trackers: An Animal Model of Poor Top Down Cognitive Control of Attention
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