1,720,983 research outputs found
Alcohol and the developing brain: Why neurons die and how survivors change
Full text linkThe consequences of alcohol drinking during pregnancy are dramatic and usually referred to as fetal alcohol spectrum disorders (FASD). This condition is one of the main causes of intellectual disability in Western countries. The immature fetal brain exposed to ethanol undergoes massive neuron death. However, the same mechanisms leading to cell death can also be responsible for changes of developmental plasticity. As a consequence of such a maladaptive plasticity, the functional damage to central nervous system structures is amplified and leads to permanent sequelae. Here we review the literature dealing with experimental FASD, focusing on the alterations of the cerebral cortex. We propose that the reciprocal interaction between cell death and maladaptive plasticity represents the main pathogenetic mechanism of the alcohol-induced damage to the developing brain
Shape facilitates number: brain potentials and microstates reveal the interplay between shape and numerosity in human vision
Full text linkRecognition of simple shapes and numerosity estimation for small quantities are often studied independently of each other, but we know that these processes are both rapid and accurate, suggesting that they may be mediated by common neural mechanisms. Here we address this issue by examining how spatial configuration, shape complexity, and luminance polarity of elements affect numerosity estimation. We directly compared the Event Related Potential (ERP) time-course for numerosity estimation under shape and random configurations and found a larger N2 component for shape over lateral-occipital electrodes (250-400ms), which also increased with higher numbers. We identified a Left Mid Frontal (LMF; 400-650ms) component over left-lateralised medial frontal sites that specifically separated low and high numbers of elements, irrespective of their spatial configuration. Different luminance-polarities increased N2 amplitude only, suggesting that shape but not numerosity is selective to polarity. Functional microstates confined numerosity to a strict topographic distribution occurring within the LMF time-window, while a microstate responding only to shape-configuration was evidenced earlier, in the N2 time-window. We conclude that shape-coding precedes numerosity estimation, which can be improved when the number of elements and shape vertices are matched. Thus, numerosity estimation around the subitizing range is facilitated by a shape-template matching process
The impact of alcohol-induced blackouts on memory in a Scottish based student population
Full text linkRapid drinking of excessive quantities of alcohol disrupts normal memory functioning and can lead to the experience of an alcohol-induced memory blackout (MBO), meaning that events which occurred while intoxicated may not be recalled once sober. Although instances of extreme binge-drinking and MBOs are prevalent in student populations, there is a paucity of knowledge surrounding the topic. Critically, 1) we do not know what the wider influences on these behaviours may be, specifically for students studying in Scotland, and 2) we also do not know whether these events leave a lasting impact on memory formation and, if so, whether this deficit is temporary. This thesis addressed these issues firstly with a questionnaire which investigated student drinking behaviours, and then with a series of laboratory-based memory studies which participants carried out sober, after a scaled dose of alcohol, and within 20-hours of experiencing a blackout. We found that students in Scotland frequently binge-drink, with a high prevalence of MBOs, influenced by home country, year of study, and possibly by Scottish culture. We also found control and experimental participant groups performed recall and recognition memory tasks with similar behavioural accuracy while sober and that performance dropped but did not differ following alcohol. However, ERP evidence suggested a shift in neural strategy in MBO participants compared to controls. Further, after-blackout performance remained impaired in more cognitively demanding tasks. In sum, evidence suggests that our Scottish-based student population drink to excess, with a large proportion experiencing regular MBOs. Alcohol impairs behavioural memory performance for all, but underlying differences in memory strategy, and a lasting deficit following MBO, can be seen in those who frequently blackout. These findings highlight the importance of further investigating the trajectory of blackout experiences, and any damage they leave in their wake
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
Confidence in memory's accuracy
Full text linkDespite accounts of a consistent and strong association between confidence and memory accuracy, they can be shown to dissociate. That belief in the truth of a memory may be influenced more by our metacognitive judgments of the memory’s quality (vividness or distinctiveness) than its factual accuracy was tested using real-world colour natural scenes photographs as retrieval cues in a continuous-response source memory task. Importantly, the correlation between memory quality and confidence was very large. Reducing the visual vividness of the images did not affect this very large correlation. Displaying pictures in a homogenous list arrangement (where all pictures represented the same natural scene category) reduced performance and memory accuracy but did not disrupt the very large correlation between distinctiveness and confidence. The correlation between accuracy and confidence remained moderate to large throughout. The relationship between accuracy and confidence was moderated by the vividness or distinctiveness of the memory, increasing confidence in the memory for the same level of accuracy, causing them to dissociate. The association between memory quality and accuracy acted largely indirectly, mediated through confidence. A 2-AFC recognition memory task, also using natural scenes photographs, reproduced the very large correlation between vividness and confidence. Remembering moderated the relationship between vividness and confidence, remembering being associated with higher confidence and higher vividness. Increases in the proportion of correct responses associated with remembering was seen only at highest levels of confidence. The 2-AFC task revealed a very large correlation between familiarity and confidence. Recollection was of less importance for accuracy when familiarity was high and of more importance when familiarity was low. The quality of a memory is associated with confident recollection, even if the detail is incorrect. The findings have implications for theoretical accounts of eyewitness testimony, illusions of memory accuracy, false memories, and dual process theory
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
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