Head position signal is crucial for preparing reaching movements because it contributes to specifying the position of body and target in space and relative to each other. However, it is unclear whether sensory information pertaining head position is used to control the movement after movement onset. In this study, nineteen participants performed discrete reaches towards a virtual target while neck vibration was randomly applied before and/or during the movement or not at all. The main dependent variable was the directional bias of the reaching finger. Neck vibration induced early leftward or late rightward trajectory biases. It appears that participants interpreted the sensed head shift as a target or an eye-in-head motion, which can be explained by individual differences in the use of reference frames. Nevertheless, body-centered and head-centered frames of reference appear to be important for the early and late stages of a goal-directed movement, respectively.

Head position signal is crucial for preparing reaching movements because it contributes to specifying the position of body and target in space and relative to each other. However, it is unclear whether sensory information pertaining head position is used to control the movement after movement onset. In this study, nineteen participants performed discrete reaches towards a virtual target while neck vibration was randomly applied before and/or during the movement or not at all. The main dependent variable was the directional bias of the reaching finger. Neck vibration induced early leftward or late rightward trajectory biases. It appears that participants interpreted the sensed head shift as a target or an eye-in-head motion, which can be explained by individual differences in the use of reference frames. Nevertheless, body-centered and head-centered frames of reference appear to be important for the early and late stages of a goal-directed movement, respectively.

Bakgrund: Nacksmärta är ett vanligt förekommande besvär och en av de främsta orsakerna till att söka vård hos fysioterapeut. Nackbesvär kan leda till förändringar i proprioception, både medveten och omedveten, vilket kan leda till en nedsatt balans. Undersökning av omedveten proprioception har gjorts genom att mäta posturalt svaj vid stimulering av muskelspolar via lokala muskelvibratorer i tidigare studier. Ingen studie har dock undersökt reliabiliteten vid stimulering av nack- och vadmuskler hos personer med respektive utan nacksmärta   Syfte: Studiens syfte var att utvärdera inter-day reliabilitet för posturalt svaj hos personer med eller utan nacksmärta genom att mäta CoP på WBB där deltagarna ges vibrationer på vader, nacke respektive underarmar.   Metod: 50 deltagare deltog i studien, 25 deltagare med nacksmärta och 25 friska kontroller. Deltagarnas CoP mättes på en WBB där deltagarnas förändring av CoP mättes innan, under och efter att vibrationer getts på vader, underarmar respektive nacken. Deltagarna testades vid två tillfällen med 7 dagars mellanrum. ICC2,1 användes för att beräknade relativ reliabilitet. Ett ICC-värde ≥ 0,75 bedöms som god reliabilitet. Absolut reliabilitet beräknades med SEM. Beroende t-test utfördes för att undersöka eventuell systematisk bias såsom adaptioner eller inlärningseffekter mellan testtillfälle 1och 2.   Resultat: Studiens resultat uppvisade en måttlig till utmärkt relativ reliabilitet (ICC = 0,69 - 0,89) för A/P amplituden för hela gruppen och SEM-värden var mellan 0,51 - 1,17 vilket utgör ca 20 - 30% av medelvärdet för de flesta svajvariablerna. En signifikant inlärningseffekt kunde ses för både A/P och M/L amplituden vid vibration av vadmuskulaturen (p = 0,015 - 0,017).   Slutsats: Studiens resultat visar på en acceptabel reliabilitet och testmetoden kan användas i såväl forskning som klinisk användning vid undersökning av posturalt svaj med eller utan vibration. / Background: Neck pain is a common occurrence and one of the main reasons for seeking care at a physiotherapist. Neck disorders can lead to changes in proprioception, both conscious and unconscious, which can lead to a reduced balance. Investigation of unconscious proprioception has been done by measuring postural sway in the stimulation of muscle spindles via local muscle vibrators in previous studies. However, no study has investigated the reliability of stimulation of neck and calf muscles in people with or without neck pain   Purpose: The purpose of the study was to evaluate inter-day reliability on postural sway in people with or without neck pain by measuring CoP on WBB where participants receive vibration on the calf, neck and forearms.   Method: 50 participants participated in the study, 25 participants with neck pain and 25 healthy controls. Participants change of CoP was measured before, during and after vibration was given to calf, forearm and neck. Participants were tested on two occasions at 7-day intervals. ICC2,1 was used to calculate relative reliability. An ICC value ≥ 0.75 is considered to be good reliability. Absolute reliability was calculated with SEM. Dependent t-test was performed to investigate any systematic bias such as adaptations or learning effects between test 1 and 2.   Results: The results of the study showed a moderate to excellent relative reliability (ICC = 0.69 - 0.89) for the A/P amplitude and SEM values ​​were between 0.51 - 1.17 which represents about 20-30% of the mean for most sway variables. A significant learning effect could be seen for both the A/P and M/L amplitude in vibration of the calf muscles (p = 0.015-0.017).   Conclusion: The results of the study demonstrate acceptable reliability and the test method can be used in research and clinical to investigate postural sway with or without vibration.

A prestação de serviços na área da saúde apresenta uma demanda por novas tecnologias. Os fisioterapeutas utilizam desde equipamentos mais simples aos mais complexos para auxiliar na elaboração do diagnóstico cinético funcional, na prescrição, planejamento, ordenação, análise, supervisão e avaliação das atividades fisioterapêuticas dos clientes. Considerando a importância da articulação do cotovelo para as atividades de vida diárias dos indivíduos, bem como a complexa reabilitação das articulações do cotovelo e radioulnares, que requerem intervenção precoce para evitar a rigidez articular, a perda de amplitude de movimento e de força; foi identificada a necessidade de desenvolver um equipamento inovador para a reabilitação do cotovelo e antebraço. Assim, essa tese tem como objetivo geral desenvolver um equipamento inovador para a reabilitação do cotovelo e antebraço. Os objetivos específicos são: (i) analisar os estudos científicos e patentes que abordam o desenvolvimento de equipamentos de Movimentação Passiva Contínua para a reabilitação do cotovelo e antebraço; (ii) realizar a análise funcional e operacional de equipamentos para a reabilitação do cotovelo a antebraço disponíveis no mercado; (iii) identificar os requisitos dos stakeholders da cadeia de valor do produto para o desenvolvimento de um equipamento inovador para a reabilitação do cotovelo e antebraço; (iv) desenvolver o módulo de vibração muscular localizada do equipamento inovador para a reabilitação do cotovelo e antebraço; (v) desenvolver o módulo de Movimentação Passiva Contínua do equipamento inovador para a reabilitação do cotovelo e antebraço; (vi) avaliar a utilização do equipamento inovador para a reabilitação do cotovelo e antebraço em seres humanos. Para atingir os objetivos desta tese foram utilizadas metodologias e ferramentas para a gestão do processo de desenvolvimento de produtos, bem como testes experimentais dos protótipos funcionais com seres humanos. Os resultados envolvem a obtenção de conhecimento científico acerca do tema do desenvolvimento de equipamentos inovadores para a área da saúde, bem como o protótipo funcional de um equipamento inovador para a reabilitação do cotovelo e antebraço, apresentados na forma de seis estudos científicos. / The healthcare service rendering requests new technologies. Physical therapists use equipments from the simplest to the most complex to assist in the developing of functional kinetic diagnosis, prescription, planning, managing, analyzing, monitoring and evaluation of customers’ therapy activities. A need of developing a novel equipment for the elbow and forearm rehabilitation came from the importance of the elbow joint for the daily living activities of people and the complex rehabilitation of elbow and radioulnar joints. These joints require early intervention to prevent joint stiffness, loss of range of motion and strength. Based on this context, the general goal of this PhD thesis is to develop a novel device for elbow and forearm rehabilitation. The specific goals are: (i) analyze the scientific studies and patents about the development of Continuous Passive Motion devices for the elbow and forearm rehabilitation; (ii) analyze functional and operationally the devices for the elbow and forearm rehabilitation which are available in the market; (iii) identify the stakeholder requirements of the device value chain to develop a novel device for the elbow and forearm rehabilitation; (iv) develop the local muscle vibration module of the novel device for the elbow and forearm rehabilitation; (v) develop the Continuous Passive Motion module of the novel device for the elbow and forearm rehabilitation; (vi) evaluate the use of the novel device for the elbow and forearm rehabilitation on human subjects. Management product development process methodogies and tools, as well as experimental tests of the functional prototypes on human subjects were used to achieve the thesis goals. The results include the generation of scientific knowledge about the development of new devices for the health area, as well as a functional prototype of the novel equipment for the elbow and forearm rehabilitation presented as six scientific studies.

A prestação de serviços na área da saúde apresenta uma demanda por novas tecnologias. Os fisioterapeutas utilizam desde equipamentos mais simples aos mais complexos para auxiliar na elaboração do diagnóstico cinético funcional, na prescrição, planejamento, ordenação, análise, supervisão e avaliação das atividades fisioterapêuticas dos clientes. Considerando a importância da articulação do cotovelo para as atividades de vida diárias dos indivíduos, bem como a complexa reabilitação das articulações do cotovelo e radioulnares, que requerem intervenção precoce para evitar a rigidez articular, a perda de amplitude de movimento e de força; foi identificada a necessidade de desenvolver um equipamento inovador para a reabilitação do cotovelo e antebraço. Assim, essa tese tem como objetivo geral desenvolver um equipamento inovador para a reabilitação do cotovelo e antebraço. Os objetivos específicos são: (i) analisar os estudos científicos e patentes que abordam o desenvolvimento de equipamentos de Movimentação Passiva Contínua para a reabilitação do cotovelo e antebraço; (ii) realizar a análise funcional e operacional de equipamentos para a reabilitação do cotovelo a antebraço disponíveis no mercado; (iii) identificar os requisitos dos stakeholders da cadeia de valor do produto para o desenvolvimento de um equipamento inovador para a reabilitação do cotovelo e antebraço; (iv) desenvolver o módulo de vibração muscular localizada do equipamento inovador para a reabilitação do cotovelo e antebraço; (v) desenvolver o módulo de Movimentação Passiva Contínua do equipamento inovador para a reabilitação do cotovelo e antebraço; (vi) avaliar a utilização do equipamento inovador para a reabilitação do cotovelo e antebraço em seres humanos. Para atingir os objetivos desta tese foram utilizadas metodologias e ferramentas para a gestão do processo de desenvolvimento de produtos, bem como testes experimentais dos protótipos funcionais com seres humanos. Os resultados envolvem a obtenção de conhecimento científico acerca do tema do desenvolvimento de equipamentos inovadores para a área da saúde, bem como o protótipo funcional de um equipamento inovador para a reabilitação do cotovelo e antebraço, apresentados na forma de seis estudos científicos. / The healthcare service rendering requests new technologies. Physical therapists use equipments from the simplest to the most complex to assist in the developing of functional kinetic diagnosis, prescription, planning, managing, analyzing, monitoring and evaluation of customers’ therapy activities. A need of developing a novel equipment for the elbow and forearm rehabilitation came from the importance of the elbow joint for the daily living activities of people and the complex rehabilitation of elbow and radioulnar joints. These joints require early intervention to prevent joint stiffness, loss of range of motion and strength. Based on this context, the general goal of this PhD thesis is to develop a novel device for elbow and forearm rehabilitation. The specific goals are: (i) analyze the scientific studies and patents about the development of Continuous Passive Motion devices for the elbow and forearm rehabilitation; (ii) analyze functional and operationally the devices for the elbow and forearm rehabilitation which are available in the market; (iii) identify the stakeholder requirements of the device value chain to develop a novel device for the elbow and forearm rehabilitation; (iv) develop the local muscle vibration module of the novel device for the elbow and forearm rehabilitation; (v) develop the Continuous Passive Motion module of the novel device for the elbow and forearm rehabilitation; (vi) evaluate the use of the novel device for the elbow and forearm rehabilitation on human subjects. Management product development process methodogies and tools, as well as experimental tests of the functional prototypes on human subjects were used to achieve the thesis goals. The results include the generation of scientific knowledge about the development of new devices for the health area, as well as a functional prototype of the novel equipment for the elbow and forearm rehabilitation presented as six scientific studies.

A prestação de serviços na área da saúde apresenta uma demanda por novas tecnologias. Os fisioterapeutas utilizam desde equipamentos mais simples aos mais complexos para auxiliar na elaboração do diagnóstico cinético funcional, na prescrição, planejamento, ordenação, análise, supervisão e avaliação das atividades fisioterapêuticas dos clientes. Considerando a importância da articulação do cotovelo para as atividades de vida diárias dos indivíduos, bem como a complexa reabilitação das articulações do cotovelo e radioulnares, que requerem intervenção precoce para evitar a rigidez articular, a perda de amplitude de movimento e de força; foi identificada a necessidade de desenvolver um equipamento inovador para a reabilitação do cotovelo e antebraço. Assim, essa tese tem como objetivo geral desenvolver um equipamento inovador para a reabilitação do cotovelo e antebraço. Os objetivos específicos são: (i) analisar os estudos científicos e patentes que abordam o desenvolvimento de equipamentos de Movimentação Passiva Contínua para a reabilitação do cotovelo e antebraço; (ii) realizar a análise funcional e operacional de equipamentos para a reabilitação do cotovelo a antebraço disponíveis no mercado; (iii) identificar os requisitos dos stakeholders da cadeia de valor do produto para o desenvolvimento de um equipamento inovador para a reabilitação do cotovelo e antebraço; (iv) desenvolver o módulo de vibração muscular localizada do equipamento inovador para a reabilitação do cotovelo e antebraço; (v) desenvolver o módulo de Movimentação Passiva Contínua do equipamento inovador para a reabilitação do cotovelo e antebraço; (vi) avaliar a utilização do equipamento inovador para a reabilitação do cotovelo e antebraço em seres humanos. Para atingir os objetivos desta tese foram utilizadas metodologias e ferramentas para a gestão do processo de desenvolvimento de produtos, bem como testes experimentais dos protótipos funcionais com seres humanos. Os resultados envolvem a obtenção de conhecimento científico acerca do tema do desenvolvimento de equipamentos inovadores para a área da saúde, bem como o protótipo funcional de um equipamento inovador para a reabilitação do cotovelo e antebraço, apresentados na forma de seis estudos científicos. / The healthcare service rendering requests new technologies. Physical therapists use equipments from the simplest to the most complex to assist in the developing of functional kinetic diagnosis, prescription, planning, managing, analyzing, monitoring and evaluation of customers’ therapy activities. A need of developing a novel equipment for the elbow and forearm rehabilitation came from the importance of the elbow joint for the daily living activities of people and the complex rehabilitation of elbow and radioulnar joints. These joints require early intervention to prevent joint stiffness, loss of range of motion and strength. Based on this context, the general goal of this PhD thesis is to develop a novel device for elbow and forearm rehabilitation. The specific goals are: (i) analyze the scientific studies and patents about the development of Continuous Passive Motion devices for the elbow and forearm rehabilitation; (ii) analyze functional and operationally the devices for the elbow and forearm rehabilitation which are available in the market; (iii) identify the stakeholder requirements of the device value chain to develop a novel device for the elbow and forearm rehabilitation; (iv) develop the local muscle vibration module of the novel device for the elbow and forearm rehabilitation; (v) develop the Continuous Passive Motion module of the novel device for the elbow and forearm rehabilitation; (vi) evaluate the use of the novel device for the elbow and forearm rehabilitation on human subjects. Management product development process methodogies and tools, as well as experimental tests of the functional prototypes on human subjects were used to achieve the thesis goals. The results include the generation of scientific knowledge about the development of new devices for the health area, as well as a functional prototype of the novel equipment for the elbow and forearm rehabilitation presented as six scientific studies.

Mechanomyography (MMG) has been proposed as a control modality for alternative access technologies for individuals with disabilities. However, MMG recordings are highly susceptible to contamination from limb movements. Pressure-based transducers are touted to be the most robust to external movement although there is some debate about their optimal chamber geometry, in terms of low frequency gain and spectral flatness. To investigate the question of preferred geometry, transducers with varying chamber shapes were designed, manufactured and tested. The best performance was achieved with a transducer consisting of a low-frequency MEMS microphone, a 4 micron thick aluminized mylar membrane and a rigid conical chamber 7 mm in diameter and 5 mm in height. Furthermore, microphone-derived MMG spectra were found to be less influenced by motion artifact than corresponding accelerometer-derived spectra. However, artifact harmonics were present in both spectra, suggesting that bandpass filtering may not remove artifact influences permeating into MMG frequency bands.

Mechanomyography (MMG) has been proposed as a control modality for alternative access technologies for individuals with disabilities. However, MMG recordings are highly susceptible to contamination from limb movements. Pressure-based transducers are touted to be the most robust to external movement although there is some debate about their optimal chamber geometry, in terms of low frequency gain and spectral flatness. To investigate the question of preferred geometry, transducers with varying chamber shapes were designed, manufactured and tested. The best performance was achieved with a transducer consisting of a low-frequency MEMS microphone, a 4 micron thick aluminized mylar membrane and a rigid conical chamber 7 mm in diameter and 5 mm in height. Furthermore, microphone-derived MMG spectra were found to be less influenced by motion artifact than corresponding accelerometer-derived spectra. However, artifact harmonics were present in both spectra, suggesting that bandpass filtering may not remove artifact influences permeating into MMG frequency bands.

Cette thèse vise à répondre à trois questions fondamentales: 1) La diminution de l’excitabilité corticospinale et le manque d’inhibition intracorticale observés suite à la stimulation magnétique transcrânienne (SMT) du cortex moteur de la main atteinte de sujets hémiparétiques sont-ils aussi présents suite à la SMT du cortex moteur de la jambe atteinte? 2) Est-ce que les altérations dans l’excitabilité corticomotrice sont corrélées aux déficits et incapacités motrices des personnes ayant subi un accident vasculaire cérébral depuis plus de 6 mois? 3) La vibration musculaire, étant la source d’une forte afférence sensorielle, peut-elle moduler l’excitabilité corticomotrice et améliorer la performance motrice de ces personnes? Premièrement, afin d’appuyer notre choix d’intervention et d’évaluer le potentiel de la vibration mécanique locale pour favoriser la réadaptation des personnes ayant une atteinte neurologique, nous avons réalisé une révision en profondeur de ses applications et intérêts cliniques à partir d’informations trouvées dans la littérature scientifique (article 1). La quantité importante d’information sur les effets physiologiques de la vibration contraste avec la pauvreté des études qui ont évalué son effet thérapeutique. Nous avons trouvé que, malgré le manque d’études, les résultats sur son utilisation sont encourageants et positifs et aucun effet adverse n’a été rapporté. Dans les trois autres articles qui composent cette thèse, l’excitabilité des circuits corticospinaux et intracorticaux a été étudiée chez 27 sujets hémiparétiques et 20 sujets sains sans atteintes neurologiques. Les fonctions sensorimotrices ont aussi été évaluées par des tests cliniques valides et fidèles. Tel qu’observé à la main chez les sujets hémiparétiques, nous avons trouvé, par rapport aux sujets sains, une diminution de l’excitabilité corticospinale ainsi qu’un manque d’inhibition intracorticale suite à la SMT du cortex moteur de la jambe atteinte (article 2). Les sujets hémiparétiques ont également montré un manque de focus de la commande motrice lors de l’activation volontaire des fléchisseurs plantaires. Ceci était caractérisé par une augmentation de l’excitabilité nerveuse des muscles agonistes, mais aussi généralisée aux synergistes et même aux antagonistes. De plus, ces altérations ont été corrélées aux déficits moteurs au membre parétique. Le but principal de cette thèse était de tester les effets potentiels de la vibration des muscles de la main (article 3) et de la cuisse (article 4) sur les mécanismes neuronaux qui contrôlent ces muscles. Nous avons trouvé que la vibration augmente l’amplitude de la réponse motrice des muscles vibrés, même chez des personnes n’ayant pas de réponse motrice au repos ou lors d’une contraction volontaire. La vibration a également diminué l’inhibition intracorticale enregistrée au quadriceps parétique (muscle vibré). La diminution n’a cependant pas été significative au niveau de la main. Finalement, lors d’un devis d’investigation croisé, la vibration de la main ou de la jambe parétique a résulté en une amélioration spécifique de la dextérité manuelle ou de la coordination de la jambe, respectivement. Au membre inférieur, la vibration du quadriceps a également diminuée la spasticité des patients. Les résultats obtenus dans cette thèse sont très prometteurs pour la rééducation de la personne hémiparétique car avec une seule séance de vibration, nous avons obtenu des améliorations neurophysiologiques et cliniques. / This thesis aims to answer three basic questions: 1) Are the decrease in corticospinal excitability and the lack of intracortical inhibition observed following transcranial magnetic stimulation (TMS) of the affected hand motor cortex of stroke patients present after TMS of the affected leg motor cortex? 2) Are the alterations in corticomotor excitability correlated with motor impairments and disabilities of subjects who have suffered a stroke for over six months? 3) Can muscle vibration, as a source of strong sensory afference modulate corticomotor excitability and improve motor performance of these subjects? First of all, to support our choice of intervention and to assess the potential of local mechanical vibration to promote the recovery of persons with neurological impairment, we conducted a thorough review of its physiological effects and clinical applications in the scientific literature (article 1). The wealth of information on the physiological effects of vibration contrasts with the lack of studies that have evaluated its therapeutic effects. Nevertheless, we found that, despite the paucity of studies, the results on its clinical use are encouraging and positive and no adverse effects were reported. In the other three articles included in this thesis, the excitability of corticospinal and intracortical circuits has been studied in 27 hemiparetic patients and in 20 healthy subjects without neurological disease or injury. Sensorimotor functions were also evaluated with valid and reliable clinical tests. Similar to that observed in the hand of hemiparetic patients, we found, compared to the healthy subjects, a decrease of corticospinal excitability and a lack of intracortical inhibition following TMS of the affected leg motor cortex (Article 2). The hemiparetic patients also showed a lack of focus of the motor output during voluntary activation of plantar flexors. This was characterized by an increase in the neural excitability not only of the agonist muscles, but also of the synergists and even the antagonist muscles. The main goal of this thesis was to test the potential effects of vibrating hand (Article 3) and thigh (Article 4) muscles on the neural mechanisms that control these muscles. We found that vibration increases the amplitude of motor responses in the vibrated muscles and even produces a response in subjects with no motor response at rest or during a voluntary contraction. The vibration also decreased the intracortical inhibition recorded in the paretic quadriceps muscle (vibrated muscle). The decrease was however not significant at the hand. Finally, using a cross-over design study, the vibration of the paretic hand or leg resulted in specific improvements in hand dexterity or leg coordination, respectively. In the lower limb, quadriceps vibration also reduced the spasticity in patients. The results obtained in this thesis are very promising for stroke rehabilitation because with a single session of vibration, we obtained neurophysiological and clinical improvements.

Cette thèse vise à répondre à trois questions fondamentales: 1) La diminution de l’excitabilité corticospinale et le manque d’inhibition intracorticale observés suite à la stimulation magnétique transcrânienne (SMT) du cortex moteur de la main atteinte de sujets hémiparétiques sont-ils aussi présents suite à la SMT du cortex moteur de la jambe atteinte? 2) Est-ce que les altérations dans l’excitabilité corticomotrice sont corrélées aux déficits et incapacités motrices des personnes ayant subi un accident vasculaire cérébral depuis plus de 6 mois? 3) La vibration musculaire, étant la source d’une forte afférence sensorielle, peut-elle moduler l’excitabilité corticomotrice et améliorer la performance motrice de ces personnes? Premièrement, afin d’appuyer notre choix d’intervention et d’évaluer le potentiel de la vibration mécanique locale pour favoriser la réadaptation des personnes ayant une atteinte neurologique, nous avons réalisé une révision en profondeur de ses applications et intérêts cliniques à partir d’informations trouvées dans la littérature scientifique (article 1). La quantité importante d’information sur les effets physiologiques de la vibration contraste avec la pauvreté des études qui ont évalué son effet thérapeutique. Nous avons trouvé que, malgré le manque d’études, les résultats sur son utilisation sont encourageants et positifs et aucun effet adverse n’a été rapporté. Dans les trois autres articles qui composent cette thèse, l’excitabilité des circuits corticospinaux et intracorticaux a été étudiée chez 27 sujets hémiparétiques et 20 sujets sains sans atteintes neurologiques. Les fonctions sensorimotrices ont aussi été évaluées par des tests cliniques valides et fidèles. Tel qu’observé à la main chez les sujets hémiparétiques, nous avons trouvé, par rapport aux sujets sains, une diminution de l’excitabilité corticospinale ainsi qu’un manque d’inhibition intracorticale suite à la SMT du cortex moteur de la jambe atteinte (article 2). Les sujets hémiparétiques ont également montré un manque de focus de la commande motrice lors de l’activation volontaire des fléchisseurs plantaires. Ceci était caractérisé par une augmentation de l’excitabilité nerveuse des muscles agonistes, mais aussi généralisée aux synergistes et même aux antagonistes. De plus, ces altérations ont été corrélées aux déficits moteurs au membre parétique. Le but principal de cette thèse était de tester les effets potentiels de la vibration des muscles de la main (article 3) et de la cuisse (article 4) sur les mécanismes neuronaux qui contrôlent ces muscles. Nous avons trouvé que la vibration augmente l’amplitude de la réponse motrice des muscles vibrés, même chez des personnes n’ayant pas de réponse motrice au repos ou lors d’une contraction volontaire. La vibration a également diminué l’inhibition intracorticale enregistrée au quadriceps parétique (muscle vibré). La diminution n’a cependant pas été significative au niveau de la main. Finalement, lors d’un devis d’investigation croisé, la vibration de la main ou de la jambe parétique a résulté en une amélioration spécifique de la dextérité manuelle ou de la coordination de la jambe, respectivement. Au membre inférieur, la vibration du quadriceps a également diminuée la spasticité des patients. Les résultats obtenus dans cette thèse sont très prometteurs pour la rééducation de la personne hémiparétique car avec une seule séance de vibration, nous avons obtenu des améliorations neurophysiologiques et cliniques. / This thesis aims to answer three basic questions: 1) Are the decrease in corticospinal excitability and the lack of intracortical inhibition observed following transcranial magnetic stimulation (TMS) of the affected hand motor cortex of stroke patients present after TMS of the affected leg motor cortex? 2) Are the alterations in corticomotor excitability correlated with motor impairments and disabilities of subjects who have suffered a stroke for over six months? 3) Can muscle vibration, as a source of strong sensory afference modulate corticomotor excitability and improve motor performance of these subjects? First of all, to support our choice of intervention and to assess the potential of local mechanical vibration to promote the recovery of persons with neurological impairment, we conducted a thorough review of its physiological effects and clinical applications in the scientific literature (article 1). The wealth of information on the physiological effects of vibration contrasts with the lack of studies that have evaluated its therapeutic effects. Nevertheless, we found that, despite the paucity of studies, the results on its clinical use are encouraging and positive and no adverse effects were reported. In the other three articles included in this thesis, the excitability of corticospinal and intracortical circuits has been studied in 27 hemiparetic patients and in 20 healthy subjects without neurological disease or injury. Sensorimotor functions were also evaluated with valid and reliable clinical tests. Similar to that observed in the hand of hemiparetic patients, we found, compared to the healthy subjects, a decrease of corticospinal excitability and a lack of intracortical inhibition following TMS of the affected leg motor cortex (Article 2). The hemiparetic patients also showed a lack of focus of the motor output during voluntary activation of plantar flexors. This was characterized by an increase in the neural excitability not only of the agonist muscles, but also of the synergists and even the antagonist muscles. The main goal of this thesis was to test the potential effects of vibrating hand (Article 3) and thigh (Article 4) muscles on the neural mechanisms that control these muscles. We found that vibration increases the amplitude of motor responses in the vibrated muscles and even produces a response in subjects with no motor response at rest or during a voluntary contraction. The vibration also decreased the intracortical inhibition recorded in the paretic quadriceps muscle (vibrated muscle). The decrease was however not significant at the hand. Finally, using a cross-over design study, the vibration of the paretic hand or leg resulted in specific improvements in hand dexterity or leg coordination, respectively. In the lower limb, quadriceps vibration also reduced the spasticity in patients. The results obtained in this thesis are very promising for stroke rehabilitation because with a single session of vibration, we obtained neurophysiological and clinical improvements.