1,721,254 research outputs found
Neuroanatomical Maps of Psychosis Onset: Voxel-wise Meta-Analysis of Antipsychotic-Naive VBM Studies
No full textBackground: Despite impressive advancements in early interventions in psychosis, there is an urgent need of robust neurobiological markers to improve the predictive value of psychosis transition. Available structural imaging literature in the field is undermined by several methodological caveats and a number of confounders such as exposure to antipsychotic treatment. Methods: Fourteen voxel-based morphometry studies of antipsychotic-naive subjects at enhanced clinical risk for psychosis (high risk [HR]) or experiencing a first-episode psychosis (FEP) were included. Formal meta-analysis of effect sizes and "signed differential mapping" voxel-based meta-analysis were combined to control the results for sample sizes, strength of individual findings, and confounding variables. Results: Formal effect size meta-analysis indicated consistent gray matter (GM) reductions both in subjects at enhanced clinical risk for psychosis and in first-episode subjects when compared with control groups. Voxel-based meta-analysis showed GM reductions in the temporal, limbic prefrontal cortex within the HR group and in the temporal insular cortex and cerebellum within the FEP group. Psychosis onset was characterized by GM decreases in temporal, anterior cingulate, cerebellar, and insular regions. GM alterations in the temporal regions directly related to severity of psychotic symptoms. There was no publication bias. Heterogeneity across studies was low. Sensitivity analyses confirmed robustness of the above results. Conclusions: Vulnerability to psychosis is associated with consistent GM decreases in prefrontal and temporolimbic areas. The onset of full disease is accompanied by temporoinsular, anterior cingulate, and cerebellar GM reductions. Neuroanatomical alterations in temporal regions may underlie the clinical onset of psychotic symptoms. © The Author 2011
Voxel-based meta-analysis of regional white-matter volume differences in autism spectrum disorder versus healthy controls
No full textBackground We conducted a meta-analysis of voxel-based morphometry (VBM) studies in autism spectrum disorder (ASD) to clarify the changes in regional white-matter volume underpinning this condition, and generated an online database to facilitate replication and further analyses by other researchers.Method PubMed, ScienceDirect, Web of Knowledge and Scopus databases were searched between 2002 (the date of the first white-matter VBM study in ASD) and 2010. Manual searches were also conducted. Authors were contacted to obtain additional data. Coordinates were extracted from clusters of significant white-matter difference between patients and controls. A new template for white matter was created for the signed differential mapping (SDM) meta-analytic method. A diffusion tensor imaging (DTI)-derived atlas was used to optimally localize the changes in white-matter volume.Results Thirteen datasets comprising 246 patients with ASD and 237 healthy controls met inclusion criteria. No between-group differences were found in global white-matter volumes. ASD patients showed increases of white-matter volume in the right arcuate fasciculus and also in the left inferior fronto-occipital and uncinate fasciculi. These findings remained unchanged in quartile and jackknife sensitivity analyses and also in subgroup analyses (pediatric versus adult samples).Conclusions Patients with ASD display increases of white-matter volume in tracts known to be important for language and social cognition. Whether the results apply to individuals with lower IQ or younger age and whether there are meaningful neurobiological differences between the subtypes of ASD remain to be investigated. © 2011 Cambridge University Press
A general approach for combining voxel-based meta-analyses conducted in different neuroimaging modalities
No full textMeta-analyses are useful to summarize the exponential amount of inconsistent and conflicting neuroimaging data. However, they are usually separately conducted for each different neuroimaging modality, preventing the multimodal integration of different imaging findings in a given neuropsychiatric disorder. Here, we describe an innovative method to meta-analytically combine the results of different imaging modalities, such as structural and functional paradigms. The method accounts for the presence of noise in the estimation of the p-values, and can be easily applied to any meta-analytical software. We hope that with this advanced imaging tool, researchers will be able to provide more complete multimodal pictures of the brain regions affected in different neuropsychiatric disorders
Systematic Review and Meta-Analysis: Reporting and Representation of Race/Ethnicity in 310 Randomized Controlled Trials of Attention-Deficit/Hyperactivity Disorder Medications
No full textObjective: To evaluate the reporting of race/ethnicity data in randomized controlled trials (RCTs) of attention-deficit/hyperactivity disorder (ADHD) medications. Secondary objectives were to estimate temporal trends in the reporting, and to compare the pooled prevalence of racial/ethnic groups in RCTs conducted in the US to national estimates. Method: We drew on, adapted, and updated the search of a network meta-analysis by Cortese et al. (2018) up to March 2022. We calculated the percentage of RCTs reporting data on race/ethnicity of participants in the published article or in related unpublished material. Temporal trends were estimated with logistic regression. The pooled prevalence of each racial/ethnic group across US RCTs was calculated using random-effects model meta-analyses. Results: We retained 310 RCTs (including 44,447 participants), of which 231 were conducted in children/adolescents, 78 in adults, and 1 in both. Data on race/ethnicity were reported in 59.3% of the RCTs (75% of which were conducted in children/adolescents and 25% in adults) in the published article, and in unpublished material in an additional 8.7% of the RCTs. Reporting improved over time. In the US RCTs, Asian and White individuals were under- and overrepresented, respectively, compared to national estimates in the most recent time period considered. Conclusion: More than 30% of the RCTs of ADHD medications retained in this review did not include data on race/ethnicity in their published or unpublished reports, and more than 40% in their published articles, even though reporting improved over time. Results should inform investigators, authors, editors, regulators, and study participants in relation to efforts to tackle inequalities in ADHD research. Plain language summary: A systematic review of 310 randomized controlled trials for attention-deficit/hyperactivity disorder (ADHD) medications found that race/ethnicity were reported in only 30% of trials. Compared to national estimates, Asian individuals were underrepresented and non-Hispanic Whites individuals were overrepresented, drawing attention to the inequities in participation in ADHD research. Diversity & Inclusion Statement: One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. We actively worked to promote sex and gender balance in our author group. While citing references scientifically relevant for this work, we also actively worked to promote sex and gender balance in our reference list. While citing references scientifically relevant for this work, we also actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our reference list. The author list of this paper includes contributors from the location and/or community where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work. Study preregistration information: Reporting and representation of race/ethnicity in double blind randomised controlled trials of medications for ADHD; https://osf.io/; hfgz8
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
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