N270 sensitivity to conflict strength and working memory: A combined ERP and sLORETA study

The event-related potential N270 component is known to be an electrophysiological marker of the supramodal conflict processing. However little is know about the factors that may modulate its amplitude. In particular, among all studies that have investigated the N270, little or no control of the conflict strength and of the load in working memory have been done leaving a lack in the understanding of this component. We designed a spatial audiovisual conflict task with simultaneous target and cross-modal distractor to evaluate the N270 sensitivity to the conflict strength (i.e., visual target with auditory distractor or auditory target with visual distractor) and the load in working memory (goal task maintenance with frequent change in the target modality). In a first session, participants had to focus on one modality for the target position to be considered (left-hand or right-hand) while the distractor could be at the same side (compatible) or at opposite side (incompatible). In a second session, we used the same set of stimuli as in the first session with an additional distinct auditory signal that clued the participants to frequently switch between the auditory and the visual targets. We found that (1) reaction times and N270 amplitudes for conflicting situations were larger within the auditory target condition compared to the visual one, (2) the increase in target maintenance effort led to equivalent increase of both reaction times and N270 amplitudes within all conditions and (3) the right dorsolateral prefrontal cortex current density was higher for both conflicting and active maintenance of the target situations. These results provide new evidence that the N270 component is an electrophysiological marker of the supramodal conflict processing that is sensitive to the conflict strength and that conflict processing and active maintenance of the task goal are two functions of a common executive attention system

Conception et évaluation de livrets pédagogiques pour le médecin généraliste du patient blessé médullaire concernant la prise en charge neuro-cutané et neuro-urologique

En moyenne, les médecins généralistes français prendront en charge deux patients blessés médullaires sur l'ensemble de leur exercice professionnel. Médecins de premier recours, ils doivent affronter une prise en charge spécifique dont l'enjeu est majeur malgré une information pauvre pour un nombre de patients limités. Nous avons réalisé une enquête de pratique auprès de trente neuf médecins généralistes de Midi-Pyrénées qui met en relief la faiblesse de la formation médicale et l'accueil enthousiaste de deux guides pratiques mis à la disposition des médecins généralistes sur la prise en charge préventive, le suivi et les premiers soins des pathologies neuro-cutané et neuro-urologique du blessé médullaire.TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF

Corrélats neuro-fonctionnels de la récupération de l'aphasie vasculaire

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Renforcement des muscles du genou déficitaire chez l'hémiplégique chronique par la méthode conventionnelle des résistances directes progressives (résultats préliminaires d'une étude contrôlée randomisée)

TOULOUSE3-BU Santé-Centrale (315552105) / SudocTOULOUSE3-BU Santé-Allées (315552109) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Disconnection, network dysfunction and cognitive impairment after traumatic brain injury

It is now widely accepted that cognitive functions depend on the integrated operation of large-scale distributed brain networks. Recent methodological advances allow both structural and functional connectivity within these networks to be studied non-invasively in vivo. These approaches hold the promise of dramatically extending our understanding of the impact of traumatic brain injury (TBI) on cognition, which should help determine strategic targets for the rehabilitation of individuals with TBI. In this thesis, I present three studies that combine structural and functional magnetic resonance imaging to test the general hypothesis that cognitive deficits after TBI arise from structural disconnection within brain networks that mediate cognitive functions. In the first study, I demonstrate that sustained attention deficits in TBI patients are related to a failure to regulate activity within a ‘default-mode’ network (DMN) thought to be involved, among others, in internally directed processes such as self-referential thought. In addition, these deficits can be predicted by the functional and structural connectivity within the DMN. Next, I present a study investigating the neural basis for inhibitory control in healthy subjects using a modified version of the Stop Signal Task (SST). This study allows a clear distinction between attentional and response inhibition processes, and paves the way for my last study, which investigates inhibitory deficits after TBI. In this study, I demonstrate that a failure of DMN deactivation during response inhibition is associated with impaired inhibitory performance in TBI patients. The ability to efficiently regulate the DMN can be predicted by the structural integrity within a remote brain network previously proposed to be involved in switching between internally and externally directed attention. This work identifies DMN dysfunction as underlying various cognitive deficits after TBI, and confirms the relevance of white matter damage in the development of brain dysfunctions after TBI.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A step forward for mirror neurons? Investigating the functional link between action execution and action observation in limb apraxia

Increasing evidence suggests that action execution and action observation are encoded by the same brain regions. This renders motor events central to the question of self and nonself discrimination (Georgieff and Jeannerod, 1998). In humans, it is widely assumed that mirror neurons link action observation and action execution networks. These neurons respond during action execution and action observation and have been found in macaque premotor and inferior parietal cortices (di Pellegrino et al., 1992; Rizzolatti et al., 1996). The evidence for human mirror neurons is far from conclusive. Nevertheless, the presence of a general action “mirroring” system is well established (Dinstein et al., 2008). Human brains encode action execution and action observation in a remarkably similar way (Rizzolatti and Craighero, 2004), but what purpose this system serves remains unclear. It has been proposed that it is involved in action recognition, action imitation, understanding of action and emotion, imitation, and the developmental and evolutionary acquisition of language. However, it is possible that coupling of the two networks is a functionless consequence of motor development. For example, during development, Hebbian coupling may link neurons that fire during action execution to those that respond during action perception

Functional Connectivity Within the Fronto-Parietal Network Predicts Complex Task Performance: A fNIRS Study

International audiencePerformance in complex tasks is essential for many high risk operators. The achievement of such tasks is supported by high-level cognitive functions arguably involving functional activity and connectivity in a large ensemble of brain areas that form the fronto-parietal network. Here we aimed at determining whether the functional connectivity at rest within this network could predict performance in a complex task: the Space Fortress video game. Functional Near Infrared Spectroscopy (fNIRS) data from 32 participants were recorded during a Resting-State period, the completion of a simple version of Space Fortress (monotask) and the original version (multitask). The intrinsic functional connectivity within the fronto-parietal network (i.e., during the Resting-State) was a significant predictor of performance at Space Fortress multitask but not at its monotask version. The same pattern was observed for the functional connectivity during the task. Our overall results suggest that Resting-State functional connectivity within the fronto-parietal network could be used as an intrinsic brain marker for performance prediction of a complex task achievement, but not for simple task performance

Responsiveness of kinematic and clinical measures of upper-limb motor function after stroke: A systematic review and meta-analysis

International audienceBackground: Kinematic analysis and clinical outcome measures with established responsiveness contribute to the quantified assessment of upper-limb function post-stroke, the selection of interventions and the differentiation of motor recovery patterns. Objective: This systematic review and meta-analysis aimed to report trends in use and compare the responsiveness of kinematic and clinical measures in studies measuring the effectiveness of constraint-induced movement, trunk restraint and bilateral arm therapies for upper-limb function after stroke. Methods: In this systematic review, randomised controlled trials implementing kinematic analysis and clinical outcome measures to evaluate the effects of therapies in post-stroke adults were eligible. We searched 8 electronic databases (MEDLINE, EMBASE, Web of Science, Scopus, CINAHL, CENTRAL, OTseeker and Pedro). Risk of bias was assessed according to the Cochrane Risk of Bias domains. A meta-analysis was conducted for repeated design measures of pre-and post-test data providing estimated standardised mean differences (SMDs). Results: We included reports of 12 studies (191 participants) reporting kinematic smoothness, movement duration and efficiency, trunk and shoulder range of motion, control strategy and velocity variables in conjunction with assessment by Motor Activity Log, Fugl-Meyer Assessment and Wolf Motor Function Test. Responsiveness was higher (i.e., non-overlap of 95% confidence intervals [CIs]) for Motor Activity Log score (SMD for amount of use 1.0, 95% CI 0.75-1.25, P < 0.001; SMD for quality of movement 0.96, 95% CI 0.72-1.20, P < 0.001) than movement efficiency, trunk and shoulder range of motion, control strategy and peak velocity. Conclusion: These results are consistent with current literature supporting the use of combined kinematic and clinical measures for comprehensive and accurate evaluation of upper-limb function post-stroke. Future research should include other design trials and rehabilitation types to confirm these findings, focusing on subgroup analysis of type of rehabilitation intervention and functional levels

6. Neuro-imagerie fonctionnelle et étude de la récupération du langage dans l’aphasie

L’aphasie est observée dans environ un 1/3 des cas d’accident vasculaire cérébral dont l’incidence en France est estimée à environ 150 000 par an. L’aphasie est aussi caractérisée par une tendance spontanée à la récupération plus ou moins complète, faisant de l’aphasie vasculaire primo-lésionnelle une sorte de « modèle » pathologique chez l’Homme dans lequel le cerveau s’adapte à une lésion et certaines fonctions du langage doivent faire l’objet d’une réinstallation ou d’un ré-apprentissage. ..

EVOLEX : apport de la reconnaissance vocale pour le diagnostic des dysfonctionnements cognitifs légers

National audienceLes troubles du langage (lexicaux et sémantiques), tout comme les troubles attentionnels, mnésiques ou des fonctions exécutives, révèlent précocement les dysfonctionnements cognitifs liés à de nombreuses atteintes pathologiques (maladies neurodégénératives, traumatismes crâniens), aux effets secondaires de certaines thérapeutiques (chimiothérapie ou radiothérapie cérébrale) ou au vieillissement. Plusieurs tests utilisant des réponses verbalisées par les patients sont ainsi utilisés pour explorer les facultés linguistiques et les fonctions exécutives à visée diagnostique : - les tests de fluence verbale sont une procédure courante comprenant ici deux tâches. La première est une fluence sémantique [1] : elle consiste à nommer des mots appartenant à la catégorie des animaux ou des fruits. La seconde correspond à de la fluidité phonémique [2] : il s'agit de nommer des mots commençant par les lettres R ou V. - lors de la tâche de dénomination d'image, les participants reçoivent une image très explicite (exemples : un igloo, un biberon, un chat) et doivent vocaliser le mot représenté sur l'image. - la tâche de génération verbale (ou association de mots) consiste à vocaliser le premier mot qui vient à l'esprit après avoir écouté un mot simple (exemples : fruit, peinture, igloo). Les progrès de la reconnaissance vocale permettent d'informatiser le recueil, le traitement et la production des résultats en gagnant en rapidité et en qualité d'analyse par rapport aux classiques passations «papier-crayon». Ainsi, le logiciel EVOLEX comprend un système qui reconnaît et analyse automatiquement la réponse vocale du sujet (patient). En effet, une reconnaissance automatique de la parole est réalisée et le temps de réponse est calculé (c'est-à-dire la période entre le début du stimulus et le début de la réponse orale du sujet). Cette transcription, actuellement basée sur Sphinx [3], utilise des modèles acoustiques du LIUM [4]. Les scores de reconnaissance avoisinent les 80 % et permettent une exploitation automatisée des résultats. Une interface web permet de corriger ce traitement automatique. EVOLEX permet une analyse fine en termes de qualité des réponses obtenues pour les tâches testées, i.e. de génération sémantique (qualité du lien sémantique) ou de fluence (groupements de mots et stratégie de changement de groupement, fréquence lexicale...). Cette utilisation de la reconnaissance vocale appliquée à des outils diagnostiques de maladies neurodégénératives ou de dysfonctionnements cognitifs permet une recherche translationnelle entre le monde de la clinique neurologique, orthophonique et neuropsychologique d'une part, et celui de la recherche fondamentale en psycholinguistique et en reconnaissance vocale d'autre part