53 research outputs found

    Cognitive intraindividual variability and white matter integrity in aging

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    The intraindividual variability (IIV) of cognitive performance has been shown to increase with aging. While brain research has generally focused on mean performance, little is known about neural correlates of cognitive IIV. Nevertheless, some studies suggest that IIV relates more strongly than mean level of performance to the quality of white matter (WM). Our study aims to explore the relation between WM integrity and cognitive IIV by combining functional (fMRI) and structural (diffusion tensor imaging, DTI) imaging. Twelve young adults (aged 18-30 years) and thirteen older adults (61-82 years) underwent a battery of neuropsychological tasks, along with fMRI and DTI imaging. Their behavioral data were analyzed and correlated with the imaging data at WM regions of interest defined on the basis of (1) the fMRI-activated areas and (2) the Johns Hopkins University (JHU) WM tractography atlas. For both methods, fractional anisotropy, along with the mean, radial, and axial diffusivity parameters, was computed. In accord with previous studies, our results showed that the DTI parameters were more related to IIV than to mean performance. Results also indicated that age differences in the DTI parameters were more pronounced in the regions activated primarily by young adults during a choice reaction-time task than in those also activated in older adults. © 2013 Nathalie Mella et al

    Moderating Effect of Cortical Thickness on BOLD Signal Variability Age-Related Changes

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    The time course of neuroanatomical structural and functional measures across the lifespan is commonly reported in association with aging. Blood oxygen-level dependent signal variability, estimated using the standard deviation of the signal, or BOLDSD , is an emerging metric of variability in neural processing, and has been shown to be positively correlated with cognitive flexibility. Generally, BOLDSD is reported to decrease with aging, and is thought to reflect age-related cognitive decline. Additionally, it is well established that normative aging is associated with structural changes in brain regions, and that these predict functional decline in various cognitive domains. Nevertheless, the interaction between alterations in cortical morphology and BOLDSD changes has not been modeled quantitatively. The objective of the current study was to investigate the influence of cortical morphology metrics [i.e., cortical thickness (CT), gray matter (GM) volume, and cortical area (CA)] on age-related BOLDSD changes by treating these cortical morphology metrics as possible physiological confounds using linear mixed models. We studied these metrics in 28 healthy older subjects scanned twice at approximately 2.5 years interval. Results show that BOLDSD is confounded by cortical morphology metrics. Respectively, changes in CT but not GM volume nor CA, show a significant interaction with BOLDSD alterations. Our study highlights that CT changes should be considered when evaluating BOLDSD alternations in the lifespan

    Segmentation Parole/Musique pour la transcription automatique

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    Colloque avec actes et comité de lecture. internationale.International audienceDans cet article nous présentons une étude sur l'utilisation des paramÚtres MFCC dans la tùche de segmentation parole/musique indispensable dans les applications de transcription automatique d'émissions radiophoniques. Nous avons étudié, l'influence du nombre de coefficients MFCC, celle des paramÚtres dynamiques et notamment celui de la variance des coefficients MFCC calculée sur une seconde. Les tests ont été effectués sur un corpus radiophonique réel et difficile et sur le corpus de Scheirer. || The speech/music segmentation process is very useful as a first step for different tasks like speech recognition or automatic transcription. In this article, we present some studies about the use of MFCC for this speech/music segmentation. We mainly use a realworld broadcast corpus with various backgrounds and superimposed segments (speech with music). We investigate the role of the number of cepstral coefficients, the influence of different kinds of dynamic parameters, and the robustness of some of them when a mismatch between train and test conditions occurs. So we can notice that the standard MFCC coefficients with the first and second derivatives achieve good results. But, better performances were obtained with dynamic parameters and mainly with the variance of the static coefficients computed on a longterm window (1s)

    Audio Indexing on the Web: a Preliminary Study of Some Audio Descriptors

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    Colloque avec actes et comité de lecture. internationale.International audienceThe "Invisible Web" is composed of documents which can not be currently accessed by Web search engines, because they have a dynamic URL or are not textual, like video or audio documents. For audio documents, one solution is automatic indexing. It consists in finding good descriptors of audio documents which can be used as indexes for archiving and search. This paper presents an overview and recent results of the RAIVES project, a French research project on audio indexing. We present speech/music segmentation, speaker tracking, and keywords detection. We also give a few perspectives of the RAIVES project

    Mapping of Structure-Function Age-Related Connectivity Changes on Cognition Using Multimodal MRI

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    The relationship between age-related changes in brain structural connectivity (SC) and functional connectivity (FC) with cognition is not well understood. Furthermore, it is not clear whether cognition is represented via a similar spatial pattern of FC and SC or instead is mapped by distinct sets of distributed connectivity patterns. To this end, we used a longitudinal, within-subject, multimodal approach aiming to combine brain data from diffusion-weighted MRI (DW-MRI), and functional MRI (fMRI) with behavioral evaluation, to better understand how changes in FC and SC correlate with changes in cognition in a sample of older adults. FC and SC measures were derived from the multimodal scans acquired at two time points. Change in FC and SC was correlated with 13 behavioral measures of cognitive function using Partial Least Squares Correlation (PLSC). Two of the measures indicate an age-related change in cognition and the rest indicate baseline cognitive performance. FC and SC—cognition correlations were expressed across several cognitive measures, and numerous structural and functional cortical connections, mainly cingulo-opercular, dorsolateral prefrontal, somatosensory and motor, and temporo-parieto-occipital, contributed both positively and negatively to the brain-behavior relationship. Whole-brain FC and SC captured distinct and independent connections related to the cognitive measures. Overall, we examined age-related function-structure associations of the brain in a comprehensive and integrated manner, using a multimodal approach. We pointed out the behavioral relevance of age-related changes in FC and SC. Taken together, our results highlight that the heterogeneity in distributed FC and SC connectivity patterns provide unique information about the variable nature of healthy cognitive aging

    Projet RAIVES (Recherche Automatique d'Informations Verbales Et Sonores) vers l'extraction et la structuration de données radiophoniques sur Internet

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    Rapport de contrat.Internet est devenu un vecteur important de la communication. Il permet la diffusion et l'Ă©change d'un volume croissant de donnĂ©es. Il ne s'agit donc plus seulement de collecter des masses importantes " d'informations Ă©lectroniques ", mais surtout de les rĂ©pertorier, de les classer pour faciliter l'accĂšs Ă  l'information utile. Une information, aussi importante soit-elle, sur un site non rĂ©pertoriĂ©, est mĂ©connue. Il ne faut donc pas nĂ©gliger la part du " Web invisible ". Le Web invisible peut se dĂ©finir comme l'ensemble des informations non indexĂ©es, soit parce qu'elles ne sont pas rĂ©pertoriĂ©es, soit parce que les pages les contenant sont dynamiques, soit encore parce que leur nature n'est pas ou difficilement indexable. En effet, la plupart des moteurs de recherche se basent sur une analyse textuelle du contenu des pages, mais ne peuvent prendre en compte le contenu des documents sonores ou visuels. Il faut donc fournir un ensemble d'Ă©lĂ©ments descripteurs du contenu pour structurer les documents afin que l'information soit accessible aux moteurs de recherche. S'agissant de documents sonores, le but de notre projet est donc, d'une part, d'extraire ces informations et, d'autre part, de fournir une structuration des documents afin de faciliter l'accĂšs au contenu. L'indexation par le contenu de documents sonores s'appuie sur des techniques utilisĂ©es en traitement automatique de la parole, mais doit ĂȘtre distinguĂ©e de l'alignement automatique d'un texte sur un flux sonore ou encore de la reconnaissance automatique de la parole. Ce serait alors rĂ©duire le contenu d'un document sonore Ă  sa seule composante verbale. Or, la composante non-verbale d'un document sonore est importante et correspond souvent Ă  une structuration particuliĂšre du document. Par exemple, dans le cas de documents radiophoniques, on voit l'alternance de parole et de musique, plus particuliĂšrement de jingles, pour annoncer les informations. Ainsi, nous pouvons considĂ©rer un ensemble de descripteurs du contenu d'un document radiophonique : segments de Parole/Musique, " sons clĂ©s ", langue, changements de locuteurs associĂ©s Ă  une Ă©ventuelle identification de ces locuteurs, mots clĂ©s et thĂšmes. Cet ensemble peut ĂȘtre bien entendu enrichi. Extraire l'ensemble des descripteurs est sans doute suffisant pour rĂ©fĂ©rencer un document sur Internet. Mais il est intĂ©ressant d'aller plus loin et de donner accĂšs Ă  des parties prĂ©cises du document. Chaque descripteur doit ĂȘtre associĂ© Ă  un marqueur temporel qui donne accĂšs directement Ă  l'information. Cependant, l'ensemble des descripteurs appartenant Ă  des niveaux de description diffĂ©rents, leur organisation n'est pas linĂ©aire dans le temps : un mĂȘme locuteur peut parler en deux langues sur un mĂȘme segment de parole, ou encore sur un segment de parole dans une langue donnĂ©e, plusieurs locuteurs peuvent intervenir. Il faut donc aussi ĂȘtre capable de fournir une structuration de l'information sur diffĂ©rents niveaux de reprĂ©sentation

    Moderating Effect of Cortical Thickness on BOLD Signal Variability Age-Related Changes

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    The time course of neuroanatomical structural and functional measures across the lifespan is commonly reported in association with aging. Blood oxygen-level dependent signal variability, estimated using the standard deviation of the signal, or “BOLDSD,” is an emerging metric of variability in neural processing, and has been shown to be positively correlated with cognitive flexibility. Generally, BOLDSD is reported to decrease with aging, and is thought to reflect age-related cognitive decline. Additionally, it is well established that normative aging is associated with structural changes in brain regions, and that these predict functional decline in various cognitive domains. Nevertheless, the interaction between alterations in cortical morphology and BOLDSD changes has not been modeled quantitatively. The objective of the current study was to investigate the influence of cortical morphology metrics [i.e., cortical thickness (CT), gray matter (GM) volume, and cortical area (CA)] on age-related BOLDSD changes by treating these cortical morphology metrics as possible physiological confounds using linear mixed models. We studied these metrics in 28 healthy older subjects scanned twice at approximately 2.5 years interval. Results show that BOLDSD is confounded by cortical morphology metrics. Respectively, changes in CT but not GM volume nor CA, show a significant interaction with BOLDSD alterations. Our study highlights that CT changes should be considered when evaluating BOLDSD alternations in the lifespan

    Harmonizing neuropsychological assessment for mild neurocognitive disorders in Europe

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    INTRODUCTION Harmonized neuropsychological assessment for neurocognitive disorders, an international priority for valid and reliable diagnostic procedures, has been achieved only in specific countries or research contexts. METHODS To harmonize the assessment of mild cognitive impairment in Europe, a workshop (Geneva, May 2018) convened stakeholders, methodologists, academic, and non-academic clinicians and experts from European, US, and Australian harmonization initiatives. RESULTS With formal presentations and thematic working-groups we defined a standard battery consistent with the U.S. Uniform DataSet, version 3, and homogeneous methodology to obtain consistent normative data across tests and languages. Adaptations consist of including two tests specific to typical Alzheimer's disease and behavioral variant frontotemporal dementia. The methodology for harmonized normative data includes consensus definition of cognitively normal controls, classification of confounding factors (age, sex, and education), and calculation of minimum sample sizes. DISCUSSION This expert consensus allows harmonizing the diagnosis of neurocognitive disorders across European countries and possibly beyond
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