1,721,018 research outputs found
Trigeminal nerve stimulation as an active control condition in TMS clinical trials: Evidence from heart-brain coupling and clinical outcomes
No full texthttp://dx.doi.org/10.13039/501100000024 Canadian Institutes of Health Researchhttp://dx.doi.org/10.13039/100008914 Ontario Brain Institutehttp://dx.doi.org/10.13039/100014597 LAM Therapeuticshttp://dx.doi.org/10.13039/100009408 Fondation Brain Canadahttp://dx.doi.org/10.13039/100000002 National Institutes of Healt
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
Transdiagnostic predictors and mechanisms of treatment response to repetitive transcranial magnetic stimulation of the dorsomedial prefrontal cortex
No full textThere are new treatment options, such as repetitive transcranial magnetic stimulation (rTMS), for patients with longstanding, treatment-resistant mental illness. Identifying brain markers predictive of, and changes associated with, rTMS treatment response could improve patient selection and thus outcomes to this intervention. Transdiagnostic abnormalities in brain networks for attention (e.g., salience network, SN) and cognitive control have been described, and the dorsomedial prefrontal cortex (dmPFC) as a potential therapeutic target. The aim of this thesis was to identify pre-treatment abnormalities of the SN and dmPFC that predicted and changed with response to dmPFC-rTMS, across three psychiatric disorders: eating disorders (ED), obsessive-compulsive disorder (OCD), and treatment-resistant depression (TRD). All three patient groups showed significant clinical benefit following dmPFC-rTMS, although TRD response was not superior to placebo. Baseline dmPFC resting state functional MRI functional connectivity (FC) in the SN correlated with the clinical response to dmPFC-rTMS across all three disorders. FC change in the SN also accompanied symptomatic improvement in OCD and ED. In TRD patients who received either active or placebo dmPFC-rTMS, clinical response was associated with normalized between-network functional connectivity between the SN and the ventromedial network (VMN), implicated in emotion processing. These findings emphasize the role of the SN as a transdiagnostic substrate of psychiatric disorders, while at the same time underscoring the significance of inter-individual variability in SN FC for predicting response and characterizing mechanisms of improvement on rTMS. These findings also highlight the importance of FC changes between networks responsible for emotion processing and cognitive control associated with treatment-non-specific symptom improvement. Looking forward, these results have important implications for understanding common elements of psychopathology across many psychiatric disorders, and the neurobiological mechanisms of rTMS and other focal non-invasive brain stimulation techniques.Ph.D
Structural Neuroimaging Predictors and Correlates of Treatment Response for rTMS in Major Depressive Disorder
Get PDFMajor Depressive Disorder (MDD) is a multifaceted condition characterized by a complex etiology and pathology. Current classification systems, which define mental disorders based on symptom clusters and clinical course, may not adequately capture the diverse range of illnesses and their distinct pathologies. This heterogeneity becomes evident when analyzing the brain's network activity as a whole since different structural and functional networks may contribute to MDD pathology and influence repetitive transcranial magnetic stimulation (rTMS) outcomes. Understanding these neural mechanisms and MDD's neuropathophysiology is essential for enhancing rTMS remission rates and predicting patient responsiveness to treatment.
This thesis focuses on identifying the structural correlates of rTMS treatment response in Major Depressive Disorder using structural MRI, a modality with greater potential for integration into clinical practice than other biomarkers. However, there is a lack of consistency among studies investigating brain structural predictors and correlates of MDD response to rTMS, and the mechanisms through which rTMS affects brain structure remain poorly understood. The objective of this thesis is to determine the structural MRI predictors and correlates of treatment response to rTMS in Major Depressive Disorder, with the ultimate goal of developing predictive tests that reduce non-response rates among treated patients and inform the development of novel treatment strategies for non-responders.
In this thesis, we present what is to our knowledge the most extensive investigation to date into the brain structural effects of rTMS in patients with MDD. Our findings provide some support for earlier research suggesting that the thickness of the left rostral anterior cingulate cortex (rACC) within the prefrontal cortex might have potential as a biomarker for predicting rTMS treatment response in MDD patients. However, it is crucial to note that the observed effects were modest in scale. This observation, coupled with the failure of some studies to replicate the robust statistical findings of previous, smaller-scale research, suggests that the use of current methods to detect such changes might be insufficiently sensitive. Indeed, our results indicate that brain structure measures, such as gray matter volume (GMV) and cortical thickness in the rACC, previously thought to be associated with treatment outcomes, may not be as reliable or consistent across diverse MDD populations as once believed. This thesis underscores the need for future research to explore other potential structural biomarkers using more advanced methodologies, such as multivariate statistical approaches or higher resolution structural imaging. The prospect of developing a clinically useful structural MRI biomarker for the rACC that could inform personalized treatment decisions in MDD seems limited based on the current analysis. In conclusion, while the large-scale studies presented in this thesis did not replicate some of the results found in prior smaller investigations, they did reveal a significant association between rTMS and brain structural changes potentially relevant to clinical practice. These finding merit further exploration in future research. Despite the difficulty in reliably detecting these brain structural markers using current neuroimaging and analytical techniques, these methods pave the way for future studies incorporating higher-resolution structural neuroimaging along with other biomarkers. Collectively, these advances could aid in predicting response and non-response to rTMS, ultimately enabling a more personalized approach to treating MDD.Ph.D
Optimizing Treatment Outcomes of Dorsomedial Prefrontal Cortex Repetitive Transcranial Magnetic Stimulation in Major Depressive Disorder.
Get PDFMajor depressive disorder (MDD) continues to challenge the field of psychiatry with its suboptimal treatment outcomes. In cases of partial or non-response to first-line treatments, alternative treatment options are available. Unfortunately, even with these pharmacological advances, there remains a proportion of patients who experience minimal relief from their depressive symptoms.
Repetitive transcranial magnetic stimulation (rTMS) is an emerging form of brain stimulation used in the treatment of refractory psychiatric and neurological disorders. The most widely used target for rTMS in MDD is the dorsolateral prefrontal cortex (DLPFC); however, the treatment outcomes it yields are moderate. Over recent years, alternative stimulation targets have emerged as a potential solution to this issue; among them is the dorsomedial prefrontal cortex (DMPFC). To our knowledge, the DMPFC has not been systematically investigated like its adjacent prefrontal counterpart, the DLPFC. Therefore, the primary aim of the present thesis is to examine, and to further optimize treatment outcomes of DMPFC-rTMS in MDD.
We addressed this research question using multiple cohorts of MDD patients receiving DMPFC-rTMS. First, we explored the safety and tolerability of DMPFC-rTMS, focusing primarily on its cognitive profile (Study I). Second, we compared treatment outcomes for DMPFC-rTMS between individuals undergoing concurrent antipsychotic pharmacotherapy versus those receiving rTMS alone (Study II). Finally, Experiments III and IV were untaken to investigate accelerated rTMS; that is, whether the pace of symptom improvement can be increased through the use of a more intensive protocol consisting of multiple daily rTMS sessions.
Encouragingly, results from this body of work demonstrate that DMPFC-rTMS is a safe and well-tolerated, treatment for MDD (Study I), even in patients undergoing concurrent antipsychotic therapy (Study II). Congruent with existing literature on accelerated rTMS, we found that the rate of improvement can be rapidly increased in some patients, by administering multiple daily sessions of rTMS (Study III), regardless of the intersession interval (Study IV). Collectively, this thesis provides support for the notion that the safety and efficacy of rTMS in MDD applies not only to the standard target, the DLPFC, but also to the DMPFC, a target of stimulation that is entering use.Ph.D
Resting-state Functional Connectivity Predicts Individual Treatment Outcomes of Repetitive Transcranial Magnetic Stimulation for Major Depressive Disorder
Get PDFRepetitive transcranial magnetic stimulation (rTMS) is an emerging treatment for treatment-resistant major depressive disorder (MDD). We recently found that treatment response to rTMS of the dorsomedial prefrontal cortex (DMPFC) was bimodal, with individual patients showing either minimal or marked improvement (Downar et al., 2013). Here, we tested whether treatment response could be predicted before initiating treatment. To this end, we trained support vector machine (SVM) classifiers on whole-brain resting-state functional connectivity magnetic resonance imaging (rs-fcMRI) data to learn the treatment outcomes of 41 patients who received rTMS of the DMPFC. The SVMs classified patients with 90% accuracy (p = 0.035, corrected). Classification was based on 9 functional connections, with a pattern of positive and negative functional connectivity in non-responders and responders, respectively. This study represents the first step towards developing a screening tool that can direct treatment decisions.M.Sc
Transdiagnostic predictors and mechanisms of treatment response to repetitive transcranial magnetic stimulation of the dorsomedial prefrontal cortex
Get PDFThere are new treatment options, such as repetitive transcranial magnetic stimulation (rTMS), for patients with longstanding, treatment-resistant mental illness. Identifying brain markers predictive of, and changes associated with, rTMS treatment response could improve patient selection and thus outcomes to this intervention. Transdiagnostic abnormalities in brain networks for attention (e.g., salience network, SN) and cognitive control have been described, and the dorsomedial prefrontal cortex (dmPFC) as a potential therapeutic target. The aim of this thesis was to identify pre-treatment abnormalities of the SN and dmPFC that predicted and changed with response to dmPFC-rTMS, across three psychiatric disorders: eating disorders (ED), obsessive-compulsive disorder (OCD), and treatment-resistant depression (TRD). All three patient groups showed significant clinical benefit following dmPFC-rTMS, although TRD response was not superior to placebo. Baseline dmPFC resting state functional MRI functional connectivity (FC) in the SN correlated with the clinical response to dmPFC-rTMS across all three disorders. FC change in the SN also accompanied symptomatic improvement in OCD and ED. In TRD patients who received either active or placebo dmPFC-rTMS, clinical response was associated with normalized between-network functional connectivity between the SN and the ventromedial network (VMN), implicated in emotion processing. These findings emphasize the role of the SN as a transdiagnostic substrate of psychiatric disorders, while at the same time underscoring the significance of inter-individual variability in SN FC for predicting response and characterizing mechanisms of improvement on rTMS. These findings also highlight the importance of FC changes between networks responsible for emotion processing and cognitive control associated with treatment-non-specific symptom improvement. Looking forward, these results have important implications for understanding common elements of psychopathology across many psychiatric disorders, and the neurobiological mechanisms of rTMS and other focal non-invasive brain stimulation techniques.Ph.D
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