Avec le projet nommé " Dynalyser ", la société MEDICAPTEURS (France, Balma) et le laboratoire PRISSMH EA4561 (Université Paul Sabatier, Toulouse III) ont obtenu un financement du Conseil Régional Midi-Pyrénées (AO AGILE-IT 2012) pour mettre au point un nouveau système embarqué de mesure des pressions plantaires. Composé d'un système communiquant sans fil avec 9 capteurs isolés par pied il permet, à partir d'un smartphone, de retourner sous la forme consciente d'une mélodie sonore (3 sons) les informations de pressions plantaires. L'objectif de ce système est d'informer en temps réel (détection de zones d'hyperpression ou au con-traire, d'une absence de pression) et de conforter ou suppléer les moyens de détection naturelle pour un contrôle de l'appui plantaire dans des activités cliniques ou sportives. Dans un premier temps, une étude a permis de développer et de valider une méthode de placement des capteurs isolés à partir de la résultante des forces enre-gistrées par chaque capteur comparée à la force externe mesurée par une plateforme de forces. Les résultats ont mis en évidence des corrélations élevées entre les données de la plateforme de forces (centre des pressions et force verticale de réaction (Fz)) et celles du Dynalyser (barycentre des pressions et Fz), confirmant la pertinence et la nécessité d'un tel placement pour une analyse de certains paramètres biomécanique de la marche aussi pré-cise que celle permise par des systèmes éprouvés d'analyse du mouvement. Dans un second temps, le dévelop-pement de la partie logicielle permettant un retour sonore a été réalisé. Une étude vérifiant la faisabilité d'une modulation de l'appui plantaire grâce au biofeedback (BFB) a été menée sur une population saine. Reprenant le principe d'un retour en " Do majeur " (FB_Gruss) validé pour son intelligibilité, les résultats révèlent une diffi-culté des participants à s'approprier rapidement le FB_Gruss lors de la marche. Ces observations mettent en évi-dence la difficulté à traiter plusieurs informations dans un laps de temps très bref (le contact pied-sol). Par ail-leurs, une variabilité naturelle importante est observée sous certaines zones (partie latérale et surtout médiale de l'avant-pied). Elle est quelque fois supérieure à la marge de tolérance mise en place pour déclencher les sons et perturbe la quantification des appuis réussis. Les résultats obtenus sont prometteurs car ils révèlent, de plus, l'absence d'effet délétère du BFB sur la répartition des pressions plantaires ipsi et controlatérale. Dans un troi-sième temps, un modèle de prédiction des pics de pressions plantaires en fonction des paramètres spatio-temporels adimensionnels (Nombre de Froude, de Strouhal et de Modela-w) a été développé. Le but est d'obtenir un système autonome, capable de moduler une mélodie en comparant les valeurs de pics de pressions obtenues en temps réel à celles du modèle de référence. Les premiers résultats révèlent une prédiction élevée des pressions sous les zones qui servent au BFB (R² > 0.95). Ce modèle devra être validé pour être incorporé au logiciel afin d'obtenir un dispositif totalement autonome permettant d'informer en temps réel de la distribution des pressions plantaires dans un contexte clinique ou sportif. / With the project named " Dynalyser ", the MEDICAPTEURS Company (France, Balma) and the PRISSMH EA4561 laboratory (Paul Sabatier University, Toulouse III) have obtained a funding by the Midi-Pyrenees Regional Council (AO AGILE-IT 2012) to develop a new plantar pressure embedded biofeedback sys-tem. Consisting of a wireless communicating system with nine isolated sensors per foot, it aims to deliver infor-mation about plantar pressures in the conscious of a sound melody (3 sounds), by means of a smartphone. The system's aim is to reinforce or supplement the intrinsic (i.e., natural) plantar pressure feedback by informing in real time (detection of hyperpressure area or, on the contrary, absence of pressure) in order to improve the con-trol of walking in clinical or sporting activities. First, a study allowed to develop and validate a method to locate isolated sensors by means of a force platform. Results revealed high correlations between the force platform data (center of pressure and vertical ground reaction force (vGRF)) and the Dynalyser data (barycenter of pressure and vGRF), confirming the relevance and necessity of such method for an analysis as precise as motion analysis systems of certain biomechanical parameters of walking. Second, the development of the auditory biofeedback (BFB) system was realized. A study verifying the feasibility of a modulation of plantar support using BFB was conducting on a healthy population. Following the principle of a "C-major" return (FB_Gruss) validated for its intelligibility, the results revealed a difficulty for the participants to appropriate quickly the FB_Gruss during walking. These observations, highlight the difficulty of processing several information in a very short period of time (the foot-to-ground contact). On the other hand, a significant natural variability is observed under two areas (lateral and especially medial part of the forefoot). It is sometimes superior to the tolerance range set up to trigger sounds and disrupts the quantification of successful supports. The results obtained are promising because they also reveal the absence of deleterious effect of the BFB on the distribution of ipsi and contralateral plantar pres-sures. Third, a model of prediction of plantar pressure peaks as a function of the dimensionless spatio-temporal parameters (Froude number, Strouhal and Modela-w) was developed. The aim is to obtain an autonomous system capable of modulating a melody by comparing the peak pressure values obtained in real time with those of the reference model. The first results reveal a high prediction of the pressures under the three areas that serve the BFB (R² > 0.95). This model must be validated to be incorporated into the software in order to obtain a totally autonomous device allowing to inform in real time the distribution of the plantar pressures in a clinical or sports context.

No description available.

A novel controller termed as Experience Mapping based Prediction Controller (EMPC) is developed in this work. EMPC is developed utilizing the broad control concepts of human motor control (HMC). The concepts of HMC are utilized to develop the core concepts of EMPC for the control of ideal Type-1 LTI systems. The control accuracy of the developed concepts is studied and the mathematical stability criterion for the controller is developed. The applicability of EMPC for the control of real world problems is tested on a Permanent Magnet DC motor based position control system. 1. Novel learning methods are presented to form experience mapped knowledge-base (EMK) which is used for the creation of the forward and inverse models. 2. Control and Adaptation Techniques which overcome the presence of non idealities are developed using the inverse model. 3. Two separate techniques which utilize the forward model for improving the adaptation capabilities of EMPC are developed. 4. Two novel techniques are developed for the improvement of the tracking performance in terms of the accuracy and smoothness of tracking. These techniques are tested under various system conditions including large dynamic parameter changes on a simulation model and a practical setup. The performance of EMPC is compared against that of PID, MRAC and LQG controllers for all the proposed techniques and EMPC is found to perform significantly better under the various system conditions in terms of transient and steady state characteristics. Finally, the effectiveness of EMPC in stabilizing unstable systems using the concepts developed is tested on a practical Inverted Pendulum system. The problem of the simultaneous development of experiences and control of the system is addressed with the stabilizing problem. The proposed controller, EMPC provides an alternative approach for the existing control of systems without the requirement of an accurate system mathematical model. Its capability to learn by directly interacting with the system and adapt using experiences makes it an attractive alternative to other control techniques present in literature. Keywords: EMPC, Position Control, PMDC motors

Made available in DSpace on 2016-06-02T20:19:14Z (GMT). No. of bitstreams: 1 3228.pdf: 1290499 bytes, checksum: b265c618eaa3f97d66f4b3ab4a0e214c (MD5) Previous issue date: 2010-08-19 / Universidade Federal de Minas Gerais / Repetitive throwing movement causes adaptations to athletes shoulders and predisposes them to the development of impingement symptoms. The objective of this study was to investigate if there are alterations in sensorimotor control and in the functional torque ratio of shoulder rotation in overhead athletes with impingement symptoms and to distinguish these from alterations due to sporting practice. To this end, three groups of subjects were evaluated: athletes with impingement symptoms, asymptomatic athletes and a control group of nonathletes. The participants were evaluated with a Biodex System 3 isokinetic dynamometer in a seated position with the shoulder at 90º of adduction and 90º of elbow flexion. Sensorimotor control was evaluated using an isometric torque steadiness evaluation. The isometric peak torque and submaximal torque steadiness at 35% peak torque were tested during medial rotation and lateral rotation of the shoulder. For each submaximal repetition, the standard deviation, coefficient of variation and time to stability were calculated. Only the standard deviation during medial rotation was greater in asymptomatic athletes than in control group. The isokinetic evaluation was carried out at the velocities 90°/s e 180°/s and 240°/ in concentric and eccentric modes. Peak torque-to-body weight and the functional torque ratios LREcc/MRCon and MREcc/LRCon were compared between groups. Asymptomatic athletes presented greater peak torque-to-body weight for concentric medial rotation at 180°/s and a lower LREcc/MRCon ratio at 90°/s and 180°/s than CG. The velocity 240°/s was excluded from the analyses because many participants were unable to reach the predetermined velocity in the eccentric tests, principally during lateral rotations. This difficulty was attributed to the low peak torque of lateral rotation that could be generated in this position. Overall, the results demonstrated that overhead sports training leads to adaptations in maximal torque and in the torque steadiness of medial rotation in healthy athletes, which may be related to throwing performance. Nevertheless, it is not possible to conclude that such alterations predispose these athletes to injury, since athletes with impingement symptoms group was not significantly different from the other groups in any of the evaluations. / O movimento repetitivo de arremesso gera adaptações no ombro de atletas, e os predispõe ao desenvolvimento de sintomas de impacto. O objetivo deste estudo foi investigar se há alterações no controle sensório-motor e na relação funcional de torque isocinético de rotação do ombro em atletas arremessadores com sintomas de impacto e diferenciar daquelas relacionadas a adaptações da prática esportiva. Sendo assim, foram avaliados três grupos de indivíduos: atletas com sintomas de impacto, atletas assintomáticos e um grupo controle de sujeitos não treinados. Os participantes foram avaliados no dinamômetro isocinético Biodex System 3, sentados, com o ombro posicionado a 90º de abdução e 90º de flexão do cotovelo. O controle sensório-motor foi avaliado por meio da flutuação do torque isométrico submáximo. O pico de torque isométrico e a flutuação do torque a 35% do pico de torque isométrico foram avaliados durante as rotações medial e lateral do ombro. Para cada repetição submáxima foram calculados o desvio-padrão, o coeficiente de variação e o tempo para atingir a estabilidade. Apenas o desvio-padrão de rotação medial foi maior no grupo de atletas assintomáticos comparado ao grupo controle. A avaliação isocinética foi realizada nas velocidades de 90°/s, 180°/s e 240°/s, nos modos concêntrico e excêntrico. O pico de torque/peso corporal e as relações funcionais de torque de rotação lateral excêntrico/rotação medial concêntrico (RLExc/RMCon) e rotação medial excêntrico/rotação lateral concêntrico (RMExc/RLCon) foram comparados entre os grupos. O grupo de atletas assintomáticos apresentou maior pico de torque/peso corporal de rotação medial concêntrica, a 180°/s, e menor relação RLExc/RMCon, a 90°/s e 180°/s, quando comparado ao controle. A velocidade de 240°/s foi excluída das análises, pois muitos participantes não conseguiram atingir a velocidade pré-determinada nos testes excêntricos, principalmente de rotação lateral. Essa dificuldade foi atribuída ao baixo pico de torque de rotação lateral capaz de ser gerado nessa posição. Em conjunto, os resultados demonstram que o treino de arremesso gera adaptações no torque máximo e na flutuação do torque submáximo de rotação medial em arremessadores saudáveis, possivelmente relacionados ao desempenho do arremesso. Entretanto, não é possível concluir se estas alterações predispõem esses atletas ao desenvolvimento de lesões, uma vez que o grupo de atletas com sintomas de impacto não se apresentou diferente dos outros grupos em nenhuma das situações avaliadas.

Ce travail exploite un modèle biomécanique de la production de la parole comme sujet de référence pour étudier plusieurs phénomènes liés à l'adaptabilité et à la stabilité du contrôle moteur de la parole, en particulier l'équivalence motrice et le contrôle postural.La première partie de cette thèse s’intéresse au phénomène de l'équivalence motrice. L'équivalence motrice est une caractéristique essentielle du contrôle moteur de la parole, car les locuteurs doivent s'adapter constamment à des contextes phonétiques toujours différents et à conditions variables de production de la parole. Le concept de « Uncontrolled Manifold » (UCM) offre un cadre théorique pour comprendre les mécanismes sous-jacents à l'équivalence motrice : il propose de représenter la coordination entre les variables de contrôle moteur en deux sous-espaces séparés, un dans lequel tout changement des variables de contrôle affectent la sortie et un autre dans lequel ces changements n'influencent aucunement la sortie.Ce concept est développé et étudié pour la production de la parole en utilisant un modèle biomécanique 2D du conduit vocal. D'abord, une représentation des UCM linéarisées basée sur des matrices de projection orthogonale est proposée. Les UCM de différentes configurations du conduit vocal des 10 voyelles orales françaises sont ensuite caractérisées en étudiant les réponses aux perturbations de leurs commandes. On étudie alors si chaque catégorie phonétique, telle que les phonèmes, les voyelles antérieures/postérieures, ou les voyelles arrondies/non-arrondies, peut être caractérisée par une UCM unique ou si les UCM varient considérablement entre les différents représentants de chacune de ces classes. On a constaté que les UCM linéarisées, celles qui sont spécifiquement calculées pour chaque configuration du conduit vocal, mais aussi celles, plus globales, des classes phonétiques, permettent une réponse efficace aux perturbations des commandes. Cela suggère que des stratégies équivalentes d'équivalence motrice peuvent être mises en œuvre dans chacune de ces classes et que les UCM en fournissent des caractérisations exploitables. Des suggestions sont faites pour de futurs travaux pour déterminer quelles classes pourraient être utilisées dans la pratique.La deuxième partie étudie dans quelle mesure le contrôle postural de la langue exploit des mécanismes passifs - tels que les propriétés mécaniques et élastiques intrinsèques de la langue- ou des réflexes à faible latence - comme le réflexe d’étirement.Une perturbation en force a été appliquée au modèle biomécanique 2D, dans laquelle la langue est tirée vers l'avant par une force exercée sur le corps de la langue à l'aide d'un robot relié à la partie supérieure de la lame de la langue. Les simulations ont été comparées à des données expérimentales recueillies au Gipsa-lab dans des conditions similaires.Cette perturbation a été simulée avec différentes valeurs du paramètre qui dans le modèle module le feedback induit par l’étirement des fibres musculaires. Les résultats ont montré un effet de rebond dans les mouvements de la langue suite à la perturbation qui est imputable au mécanisme réflexe. Étant donné qu'un rebond similaire est observé dans les données expérimentales sur des sujets humains, ce résultat suggère qu’un mécanisme réflexe joue un rôle significatif dans la stabilité posturale de la langue. Les caractéristiques temporelles de ce réflexe ont été analysées et il s’avère que la précision du modèle est insuffisante pour tirer des conclusions sur l'origine, corticale ou spinale, de ce réflexe. Des pistes pour de futures études expérimentales sont proposées. / This work makes use of a biomechanical model of speech production as a reference subject to address several phenomena related to the adaptability and stability of speech motor control, namely motor equivalence and postural stability. The first part of this thesis is related to the phenomenon of motor equivalence. Motor equivalence is a key feature of speech motor control, since speakers must constantly adapt to various phonetic contexts and speaking conditions. The Uncontrolled Manifold (UCM) idea offers a theoretical framework for considering motor equivalence in which coordination among motor control variables is separated into two subspaces, one in which changes in control variables modify the output and another one in which these changes do not influence the output.This concept is developed and investigated for speech production using a 2D biomechanical model. First, a representation of the linearized UCM based on orthogonal projection matrices is proposed. The UCMs of various vocal tract configurations of the 10 French oral vowels are then characterized using their command perturbation responses. It is then investigated whether each phonetic class such as phonemes, front/back vowels, rounded/un-rounded vowels can be characterized by a unique UCM, or whether the UCMs vary significantly across representatives of these different classes. It was found that linearized UCMs, especially those that are specifically computed for each configuration, but also across many of the phonetic classes allow for a command perturbation response that is effective. This suggests that similar motor equivalence strategies can be implemented within each of these classes and that UCMs provide a valid characterization of an equivalence strategy. Further work is suggested to elaborate which classes might be used in practice.The second part addresses the question of the degree to which postural control of the tongue is accomplished through passive mechanisms - such as the mechanical and elastic properties of the tongue itself - or through short-latency reflexes - such as the stretch reflex.A specific external force perturbation, was applied to the 2D biomechanical model , namely one in which the tongue is pulled anteriorly using specific force profile exerted on the tongue body using a force effector attached to the superior part of the tongue blade. Simulation results were compared to experimental data collected at Gipsa-lab under similar conditions.This perturbation was simulated with various values of the model's parameter modulating the reflex strength (feedback gain). The results showed that a perturbation rebound seen in simulated data is due to a reflex mechanism. Since a compatible rebound is seen in data from human subjects, this can be taken as evidence of a reflex mechanism being involved in postural stability of the tongue. The time course of the mechanisms of this reflex, including the generation of force and the movement of the tongue, were analyzed and it was determined that the precision of the model was insufficient to make any conclusions on the origin of this reflex (whether cortical or brainstem). Still, numerous experimental directions are proposed.

Le syndrome des mouvements en miroir congénitaux (MMC) est une maladie génétique caractérisée par l’existence de mouvements involontaires symétriques d’une main qui reproduisent à l’identique les mouvements volontaires de l’autre main. Deux structures sont impliquées dans la physiopathologie de cette maladie : le corps calleux (CC) et le faisceau corticospinal (FCS). Deux gènes ont été liés aux MMC à ce jour : DCC et RAD51. Tandis que DCC joue un rôle crucial dans le guidage des axones commissuraux, RAD51 intervient dans la réparation de l’ADN, et son rôle dans le développement du système moteur était inattendu.Chez la souris, nous avons étudié le rôle de RAD51 et DCC dans le développement du FCS et du CC, ainsi que l’implication de ces deux structures dans la latéralisation du contrôle moteur. Nous avons prouvé que DCC contrôle le guidage du FCS à la ligne médiane de façon indirecte. RAD51 intervient dans le développement du neocortex, mais son rôle précis dans le développement du système moteur demeure inconnu. Nous avons par ailleurs comparé un groupe de patients MMC à des volontaires sains afin d’étudier la latéralisation de l’activité corticale lors de la préparation motrice. L’activation et les interactions inter-hémisphériques des aires motrices sont anormales dès la préparation du mouvement chez les patients MMC. L’inhibition de l’aire motrice supplémentaire (AMS) chez les volontaires sains reproduit les défauts d’interactions inter-hémisphériques observés chez les patients. Ces résultats suggèrent que l’AMS est impliquée dans la préparation des mouvements latéralisés, potentiellement en modulant les interactions entre les deux hémisphères via le CC. / Mirror movements are involuntary symmetrical movements of one side of the body that mirror voluntary movements of the other side. Congenital mirror movements (CMM) is a rare genetic disorder transmitted in autosomal dominant manner, in which mirror movements are the only clinical abnormality. Two structures are involved in the physiopathology of CMM: the corpus callosum (CC) and the corticospinal tract (CST). The two main culprit genes identified so far are DCC and RAD51. While the role of DCC in commissural axons guidance during development is well known, RAD51 is involved in DNA repair, and its link with CMM was totally unexpected. In mice, we investigated the role of RAD51 and DCC in the development of the CC and CST, as well as the role of these two structures in motor lateralization. We showed that DCC controls CST midline crossing in an indirect manner. Our work clarified the role of RAD51 in neocortex development, but how RAD51 influences motor system development remains unknown. We compared a group of CMM patients with healthy volunteers to investigate the lateralization of cortical activity during movement preparation. We showed that activation of motor/premotor areas and interhemispheric interactions during movement preparation differed between the CMM patients and healthy volunteers. Transient inhibition of the supplementary motor area (SMA) in the healthy volunteers resulted in abnormal interhemispheric interactions during movement preparation, reminiscent of the situation observed in the patients. These results suggest the SMA is involved in lateralized movements preparation, potentially by modulating interhemispheric interactions via the CC.

LES CARTES SENSORIMOTRICES DE LA PAROLE : Corrélats neurocognitifs et couplage fonctionnel des systèmes de perception et de production des voyelles du Français --- La parole est construite sur un jeu de correspondances entre représentations sensorielles et articulatoires, notamment lors de l'acquisition du langage les premières années de vie. Par l'utilisation de l'imagerie par résonance magnétique fonctionelle, l'objectif premier de nos travaux était de déterminer, chez l'adulte, un possible couplage fonctionnel des systèmes de perception et de production des voyelles du Français, considérées comme unités élémentaires de la parole. En parallèle, nos travaux devaient permettre de clarifier les structures cérébrales liées au contrôle moteur orofacial de mouvements simples supralaryngés et, à l'aide de la technique de stimulation magnétique transcrânienne, de déterminer une possible implication causale des régions sensorielles et motrices lors de la perception de la parole. Nos travaux ont permis de souligner l'implication des régions sensorielles et motrices aussi bien lors de la réalisation des gestes orofaciaux que lors de la production et de la perception des voyelles. La mise en évidence d'un effet d'adaptation pour ces régions motrices, auditives et somatosensorielles lors de l'écoute ou de la réalisation répétée d'une même voyelle ou d'un même geste suggère de plus l'existence de boucles sensorimotrices communes, impliquées dans des mécanismes adaptatifs de contrôle en ligne des gestes de parole perçus et produits. Enfin, nous avons pu démontrer le rôle causal et fonctionnel des régions sensorielles et motrices de la voie dorsale lors de la catégorisation de sons de parole. Pris ensemble, nos travaux soulignent la nature distribuée sensorimotrice des représentations cérébrales des unités de parole. Mots clés: perception et production de la parole, voyelles, contrôle moteur orofacial, interactions sensorimotrices, représentations et cartes neurocognitives, IRMf, TMS. / SENSORIMOTOR MAPS OF SPEECH: Neurocognitive correlates and functional coupling of French vowel perception and production systems --- Speech is built on a set of correspondences between sensory and articulatory representations, especially during the acquisition of language in the early years of life. Using functional magnetic resonance imaging, the primary goal of our work was to determine, in adults, a possible functional coupling of French vowel perception and production systems, as elementary speech units. In parallel, our work should help clarify the brain structures related to the orofacial motor control of simple supralaryngeal movements and to determine a possible causal contribution of sensory and motor regions during speech perception. Our work highlights the involvement of sensory and motor areas when performing orofacial gestures and during vowel production and perception. Adaptive effects of these motor, auditory and somatosensory regions during repeated orofacial movements and in vowel perception and production suggest the existence of common adaptive mechanisms involved in the online control of perceived and produced speech gestures. Finally, we demonstrated a causal and functional role of the sensorimotor regions of the dorsal pathway in speech categorization. Taken together, our results emphasize the distributed sensorimotor nature of cerebral representations of speech units. Key words: speech perception and production, vowels, orofacial motor control, sensorimotor interactions, neurocognitive representations and maps, fMRI, TMS.

Chez l’humain, les corrélats EEG du système de supervision de l’action ont largement été explorés dans le cadre de travaux sur la prise de décision, mettant en évidence plusieurs potentiels évoqués caractéristiques du traitement des erreurs de sélection de l'action. Typiquement, les tâches employées impliquent des réponses motrices élémentaires et l’évaluation des performances est de nature catégorielle. En contraste, l'EEG n'a que rarement été associée à des tâches motrices plus complexes, dans lesquelles les erreurs d'exécution du mouvement correspondent à des événements spatio-temporels variant en amplitude de manière continue. Pour explorer les corrélats EEG du traitement des erreurs d’exécution du mouvement nous avons enregistré l'activité cérébrale de participants engagés dans des tâches d'adaptation visuomotrice impliquant des perturbations mécaniques ou visuelles.Dans une première étude, nous avons identifié une négativité fronto-centrale sensible à la taille des erreurs cinématiques. Sa forte similitude avec la négativité liée au feedback (FRN), classiquement associée aux erreurs de prédiction de la récompense (EPR) suggère que le traitement des erreurs de prédiction sensorielles recrute des processus neuronaux communs à celui des EPR. Dans une seconde étude, nous avons exploré la sensibilité de l'activité oscillatoire β aux erreurs cinématiques. Nous avons ainsi mis en évidence deux patrons de modulation distincts. Alors que la modulation du rebond β post-mouvement serait liée à la saillance des erreurs cinématiques indépendamment de l’adaptation sensorimotrice, la modulation de la puissance β pré-mouvement semble être le reflet de mécanismes adaptatifs. / In humans, EEG correlates of performance monitoring have been extensively investigated in relation to decision-making theories. Event-related potentials correlates of error processing have been well documented using choice reaction-time tasks in which very simple motor responses are required. In these tasks, errors concern inappropriate action selection only and the evaluation of the performance is discrete (e.g. failure or success). In contrast, EEG activity has been much less examined in more complex motor tasks in which inaccurate movement-execution produces errors that vary continuously in magnitude. Our goal was to explore EEG correlates of movement-error processing and sensorimotor adaptation. In this purpose, we recorded EEG while volunteers performed reaching movements under mechanically or visually perturbed conditions. In a first study, we identified a fronto-central negativity whose amplitude was modulated by the size of movement errors. This potential presents great similarities with the Feedback Related Negativity (FRN), a potential often assumed to reflect reward-prediction errors (RPE). These findings suggest that the processing of movement-execution errors, corresponding to sensory-prediction errors, and the processing of RPE involve a shared neural network. In a second study we assessed β-power sensitivity to errors and found two clearly distinct patterns of β-band modulation. Our results suggest that the postmovement β-power may reflect error-salience processing independent of sensorimotor adaptation whereas modulations in the foreperiod may directly relate to the motor-command adjustments activated after movement-execution errors are experienced.

Made available in DSpace on 2016-12-12T17:32:55Z (GMT). No. of bitstreams: 1 MARCELO ANDERSON BRACHT.pdf: 528517 bytes, checksum: fda430f0ee52869b14f2380311059025 (MD5) Previous issue date: 2013-05-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neck pain is a highly prevalent disease that leads to disability; individuals with neck pain experience changes in pressure pain threshold, latency activation of the neck muscles and in grip force control. However, there are few studies investigating the effectiveness of physiotherapy interventions on these changes, for example, cervical manipulation. The aim of this study was to investigate the effects of cervical manipulation on pain and upper limb motor control in subjects with neck pain. Thirty subjects with neck pain were instructed to grasp an object that was placed on a table, pre and post intervention, which consisted of or cervical manipulation (n = 15) or sham manipulation (n = 15). The data of the pain threshold, grip force and electrical activity of the upper limb muscles were collected during the task. A blinded evaluator assessed the variables of grip force control and latency of muscles in relation to the object lifting. The analysis of covariance (ANCOVA) identified a statistically significant difference (F = 7.46, P = 0.01) between groups for pressure pain threshold in the upper trapezius region, no significant differences were found for the other variables. The results of this study showed that cervical manipulation causes immediate local hypoalgesia, without however, change the motor control of the upper limb muscles. These results encourage future studies to investigate the cervical manipulation effects on motor control, in the medium and long term, using this and other dynamic tasks. / A cervicalgia é uma doença de alta prevalência que leva a incapacidade funcional; indivíduos com cervicalgia apresentam alterações no limiar de dor à pressão, na latência de ativação dos músculos cervicais e no controle da força de preensão manual. No entanto, são escassos os estudos que investigam a efetividade de intervenções fisioterapêuticas sobre essas alterações, por exemplo, a manipulação cervical. O objetivo do presente estudo foi investigar os efeitos da manipulação cervical sobre a dor e o controle motor do membro superior em indivíduos com cervicalgia. Trinta sujeitos com cervicalgia foram instruídos a pegar e levantar um objeto que foi posicionado sobre uma mesa, pré e pós intervenção, que consistiu de ou manipulação cervical (n=15) ou manipulação placebo (n=15). Os dados do limiar de dor, da força de preensão e da atividade elétrica dos músculos do membro superior foram coletados durante a tarefa. Um avaliador cego analisou as variáveis de controle de força de preensão e a latência dos músculos em relação ao levantamento do objeto. Através da análise de covariância (ANCOVA) identificou-se uma diferença estatisticamente significativa (F= 7.46, p=0.01) entre os grupos para o limiar de dor à pressão na região do trapézio superior; não foram encontradas diferenças significativas para as demais variáveis estudadas. Os resultados desse estudo mostraram que a manipulação cervical provoca hipoalgesia imediata local, sem no entanto, alterar o controle motor dos músculos do membro superior. Esses resultados incentivam futuros estudos a investigar os efeitos da manipulação cervical a médio e longo prazo sobre o controle motor, mediante essa e outras tarefas dinâmicas.

Made available in DSpace on 2014-12-17T14:44:19Z (GMT). No. of bitstreams: 1 JefersonTPR_DISSERT.pdf: 1206303 bytes, checksum: 925c332309b72a390145b34b32b2ac27 (MD5) Previous issue date: 2014-03-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Introduction: The sport practiced by people with disabilities has been growing in recent years. Consequently, advances in assessment and training methods have emerged. However, the paralympic sport keeps in tow these advances, with few specific studies that consider disability as intervening factor. The transcranial direct current stimulation (tDCS) is a technique that has proven to be capable of modulating brain function. Studies show beneficial effects of tDCS on muscle strength, power and fatigue during exercise. Objective: Investigate de the effect of tDCS on movement control in para-powerlifters. Methods: Eight subjects underwent two sessions of motion capture, which previously applied the anodic tDCS or sham sessions in the cerebellum. Three movements were performed with increasing load between 90-95% of 1MR. The movements were recorded by an 10 infrared cameras system which reconstructed the 3D trajectory of markers placed on the bar. Results: There have been changes between the anodic and sham conditions over bar level (initial, final, maximum during the eccentric and concentric phase) and in the difference between the final and initial bar level. Moreover, there was difference in bar level (final and during the eccentric phase) comparing athletes amputees and les autres. Conclusion: The findings of this study suggest that tDCS applied prior to the exercise over the cerebellum in para-powerlifters acts differently according to disability / Introdu??o: O esporte praticado por pessoas com defici?ncia vem crescendo nos ?ltimos anos. Consequentemente, avan?os nos m?todos de avalia??o e treinamento t?m surgido. Por?m, o esporte paral?mpico segue a reboque destes avan?os, com poucos estudos espec?ficos que considerem a defici?ncia como fator interveniente. A estimula??o transcraniana por corrente cont?nua (ETCC) ? uma t?cnica que vem se mostrando capaz de modular a fun??o cerebral. Estudos mostram efeitos ben?ficos da ETCC sobre a for?a muscular, fadiga e pot?ncia durante exerc?cio. Objetivo: Investigar o efeito da ETCC sobre o controle do movimento em para-halterofilistas. Metodologia: Oito sujeitos foram submetidos a duas sess?es de captura de movimentos, sendo aplicado previamente as sess?es ETCC an?dica ou sham no cerebelo. Foram realizados tr?s movimentos com carga crescente entre 90-95% de 1RM. Os movimentos foram gravados por um sistema com 10 c?meras infravermelho e tiveram reconstru?da a trajet?ria 3D de marcadores colocados na barra. Resultados: Houveram mudan?as entre as condi??es an?dica e sham sobre os desn?veis inicial, final, m?ximos durante a fase exc?ntrica e conc?ntrica e sobre a diferen?a entre o desn?vel inicial e final. Al?m disto, houve diferen?a no desn?vel final e durante a fase exc?ntrica ao comparar os atletas amputados e les autres. Conclus?o: Os achados do presente estudo sugerem que a ETCC aplicada previamente ao exerc?cio sobre o cerebelo em para-halterofilistas atua de forma diferenciada de acordo com a defici?ncia