7 research outputs found
Structural brain complexity and cognitive decline in late life : A longitudinal study in the Aberdeen 1936 Birth Cohort
Copyright © 2014 Elsevier Inc. All rights reserved.Peer reviewedPostprin
Ambient air pollution and neurotoxicity on brain structure: Evidence from women's health initiative memory study: Neurotoxic Air Pollution and WMV
To examine the putative adverse effects of ambient fine particulate matter (PM2.5) on brain volumes in older women
Efficacy of MRI data harmonization in the age of machine learning. A multicenter study across 36 datasets
Pooling publicly-available MRI data from multiple sites allows to assemble
extensive groups of subjects, increase statistical power, and promote data
reuse with machine learning techniques. The harmonization of multicenter data
is necessary to reduce the confounding effect associated with non-biological
sources of variability in the data. However, when applied to the entire dataset
before machine learning, the harmonization leads to data leakage, because
information outside the training set may affect model building, and potentially
falsely overestimate performance. We propose a 1) measurement of the efficacy
of data harmonization; 2) harmonizer transformer, i.e., an implementation of
the ComBat harmonization allowing its encapsulation among the preprocessing
steps of a machine learning pipeline, avoiding data leakage. We tested these
tools using brain T1-weighted MRI data from 1740 healthy subjects acquired at
36 sites. After harmonization, the site effect was removed or reduced, and we
measured the data leakage effect in predicting individual age from MRI data,
highlighting that introducing the harmonizer transformer into a machine
learning pipeline allows for avoiding data leakage
Cerebral magnetic resonance imaging in quiescent Crohnâs disease patients with fatigue
FSW - Self-regulation models for health behavior and psychopathology - ou
Cognitive reserve modulates brain structure and cortical architecture in the Alzheimerâs Disease
Background:Cognitive reserve (CR) explains the individual resilience to neurodegeneration. Objective:The present study investigated the effect of CR in modulating brain cortical architecture. Methods:278 individuals [110 Alzheimerâs disease (AD), 104 amnestic mild cognitive impairment (aMCI) due to AD, 64 healthy subjects (HS)] underwent a neuropsychological evaluation and 3T-MRI. Cortical thickness (CTh) and fractal dimension (FD) were assessed. Years of formal education were used as an index of CR by which participants were divided into high and low CR (HCR and LCR). Within-group differences in cortical architecture were assessed as a function of CR. Associations between cognitive scores and cortical measures were also evaluated. Results:aMCI-HCR compared to aMCI-LCR patients showed significant decrease of CTh in the right temporal and in the left prefrontal lobe. Moreover, they showed increased FD in the right temporal and in the left temporo-parietal lobes. Patients with AD-HCR showed reduced CTh in several brain areas and reduced FD in the left temporal cortices when compared with AD-LCR subjects. HS-HCR showed a significant increase of CTh in prefrontal areas bilaterally, and in the right parieto-occipital cortices. Finally, aMCI-HCR showed significant positive associations between brain measures and memory and executive performance. Conclusion:CR modulates the cortical architecture at pre-dementia stage only. Indeed, only patients with aMCI showed both atrophy (likely due to neurodegeneration) alongside richer brain folding (likely due to reserve mechanisms) in temporo-parietal areas. This opposite trend was not observed in AD and HS. Our data confirm the existence of a limited time-window for CR modulation at the aMCI stage
Biomarqueurs de la morphologie du cortex cérébral par imagerie par résonance magnétique (IRM) anatomique : application à la maladie d'Alzheimer
Les modifications de la morphologie du cortex cĂ©rĂ©bral induites par la maladie d'Alzheimer Ă ses stades prĂ©coces contribuent Ă l'intĂ©rĂȘt croissant Ă l'Ă©gard des biomarqueurs de la morphologie corticale. Ceux-ci permettraient notamment une meilleure comprĂ©hension de l'impact de cette pathologie sur l'anatomie cĂ©rĂ©brale et une dĂ©tection plus prĂ©coce de la maladie. L'originalitĂ© de notre travail par rapport au reste de la littĂ©rature est de s'intĂ©resser Ă la morphologie des surfaces interne (interface substance blanche / substance grise) et externe (interface substance grise / liquide cĂ©rĂ©bro-spinal) du cortex cĂ©rĂ©bral. Dans cette perspective, nous avons dĂ©veloppĂ© des mĂ©thodes d'estimation de la courbure et de la dimension fractale des surfaces corticales. A partir de ces biomarqueurs morphologiques et de l'Ă©paisseur corticale dont la mĂ©thode d'estimation a Ă©tĂ© prĂ©cĂ©demment dĂ©veloppĂ©e dans le laboratoire, nous avons explorĂ© l'impact de la maladie d'Alzheimer sur la morphologie du manteau cortical et nous avons Ă©valuĂ© leur apport individuel et celui de leur association au diagnostic prĂ©coce de la maladie. Nos rĂ©sultats montrent une influence significative de la pathologie sur la morphologie des sillons et sur celle des circonvolutions des surfaces corticales interne et externe. En termes d'application diagnostique, nous montrons que prises isolĂ©ment, l'Ă©paisseur corticale prĂ©sente une meilleure capacitĂ© prĂ©dictive que la courbure corticale, nous ne constatons en revanche aucune capacitĂ© prĂ©dictive de la dimension fractale. Par contre, nous montrons que l'utilisation conjointe de l'Ă©paisseur corticale et de la courbure permet une amĂ©lioration significative du diagnostic prĂ©coce.Morphological alterations of the cortical mantle in early stage of Alzheimer's disease have led to an increasing interest towards morphological biomarkers of the cerebral cortex. By providing a quantitative measure of the cortical shape, morphological biomarkers could provide better understanding of the impact of the disease on the cortical anatomy and play a role in early diagnosis. Therefore, as a primary goal in this study, we developed cortical surface curvature and fractal dimension estimation methods. We then applied those methods, together with the estimation of cortical thickness, to investigate the impact of Alzheimer's disease on the cortical shape as well as the contribution of cortical thickness and cortical curvature to the early diagnosis of Alzheimer's disease. The originality of this work lies in the estimation of sulcal and gyral curvature of the internal (gray matter/white matter boundary) and external (gray matter/cerebrospinal fluid boundary) cortical surfaces in addition to the fractal dimensions of these boundaries. Our results showed significant impact of Alzheimer's disease on sulcal and gyral shapes of the internal and external cortical surfaces. In addition, cortical thickness was found to have better ability than cortical curvature for the early diagnosis of Alzheimer's disease; no significant ability for the early diagnosis was found using fractal dimension. However, we found significant improvement in early diagnosis by combining cortical thickness and cortical curvature
Velocidad de procesamiento de la informaciĂłn en traumatismos craneoencefĂĄlicos
Tesis inĂ©dita de la Universidad Complutense de Madrid, Facultad de PsicologĂa, Departamento de PsicologĂa BĂĄsica II (Procesos Cognitivos), leĂda el 14-10-2014Depto. de PsicologĂa Experimental, Procesos Cognitivos y LogopediaFac. de PsicologĂaTRUEunpu