We followed the immediate effect of sensorimotor training on postural stability in patients with spinocerebellar ataxia (SCA). We have tried to explain the possible mechanisms of adaptation to change COP, motor learning and neuroplasticity in the field of neurodegenerative changes in the cerebellum. Research Methods: A total of 10 patients with spinocerebellar ataxia (6 men, 4 women) aged 34-71 years, with an average disease duration of 11.6 years participated in the measurement of postural stability. First, we measured the patients with SCA before and after a 15-minute sensorimotor-training exercise, then this group underwent another day of the same measurement without sensorimotor training. As a second control group of 10 healthy subjects served a similar age, who also underwent sensorimotor training. Then we compared the results of posturographic measurement. Results: In the group of SCA patients, sensorimotor training was found significantly lower values in the monitored parameters LENGTH (t stat = 3,537731 > t krit = 2,262157), VELOCITY (t stat = 3,537731 > t krit = 2,262157) and energy to sustain COP (t stat = 2,715085 > t krit = 2,262157), measured on a foam pad with eyes closed. Measurement without making sensorimotor training produced no significant improvement in the results of monitored...

Le contrôle sensorimoteur du pied est le fondement des adaptations de l’Homme à son environnement. La station debout et la marche nécessitent l’intervention de toutes les composantes du contrôle sensorimoteur, les mécanorécepteurs plantaires renseignant le système nerveux central sur la position du corps dans l'espace. Notre travail de thèse a consisté en un premier temps à établir un protocole permettant de quantifier la sensation tactile plantaire qui nous a permis de nous intéresser à l’effet des orthèses plantaires sur la perception tactile plantaire. Nos résultats mettent en évidence chez la majorité de nos sujets, que les orthèses appliquées sur les seuls appuis rétrocapitaux augmentent la discrimination des plus faibles charges mécaniques après 30 jours de port de semelles. Ces variations dépendent de la position du pied lors de la station debout et du pattern de marche. Nous avons aussi exploré le contrôle moteur lors du maintien de la station debout et d’un exercice de course à vitesse maximale. Après un effort statique maximal recrutant de façon sélective les muscles inverseurs du pied (tibialis antérior, TA), les surfaces d’appui plantaires et la surface du trajet du barycentre augmentent, il existe une altération du réflexe myotatique dans le seul TA faisant suite à des signes de fatigue électromyographique (réduction de fréquence médiane) après appui maximal. Faisant suite à un effort dynamique maximal (course sur tapis roulant), nous observons les mêmes phénomènes : augmentation des surfaces d’appui plantaire et du trajet du barycentre des pressions, et diminution de la fréquence médiane dans le seul muscle TA aux vitesses de course les plus élevées. / The sensorimotor control of foot placement and motion plays a key role in the adaptive response of human being to his environment. The participation of both sensory and motor components is needed to control the foot placement during gait and posture and mechanoreceptors in the foot sole give major information on the body position. First, we established a protocol to quantify the sensation of foot sole pressure stimulation, which allowed us to examine the effects of metatarsal pads, and heel lifts in healthy subjects. We observed that 30-days of occupational activities with metatarsal pads elicited significant changes in sensation, lowering the threshold for the detection of the lowest pressure loads and, depending on the pattern of foot placement during upright standing and walking, modifying the global gain for the foot sensation. Second, we examined the consequences of fatiguing static contraction of foot invertor muscles (tibialis anterior or TA) and of maximal running exercise on a treadmill on post-test changes in foot placement using a baropodometer, maximal force production by TA. Power spectrum analyses of electromyographic (EMG) events were performed during both static and dynamic efforts and we also explored the myotatic reflexes through the recording of the tonic vibratory response (TVR) in foot muscles. Our results showed significant changes in post-test foot placement in the direction of foot eversion in both situations, significant decrease in maximal inversion force, a leftward shift of EMG spectrum in the sole TA muscle, indicating EMG signs of fatigue, and 4) significant reduction of TVR amplitude in the sole TA muscle after sustained static effort.

À ce jour, le rôle des oscillations bêta n’a pas encore été clairement établi. Des travaux récents ont montré que l’activité bêta pendant la préparation du mouvement et celle suivant son exécution sont différemment modulées par les erreurs de mouvements. L’objectif du présent travail a été double : premièrement, déterminer si les modulations de puissance bêta pré- et post-mouvement recrutent des substrats cérébraux différents, deuxièmement, mieux cerner la nature des processus neuronaux reflétés. Grâce à une approche par analyse en composantes indépendantes, nous suggérons fortement que les réponses oscillatoires, aux erreurs cinématiques, observées avant et après le mouvement sont sous-tendues par des structures distinctes, respectivement clairement latéralisées et médiales. De plus, en contrastant différentes tâches motrices, nous montrons que ni l’une ni l’autre des deux activités bêta ne reflètent des mécanismes en lien direct avec les sorties motrices. / The role of beta oscillations has not been clearly established yet. Recent work has shown that the beta activities observed during the preparation phase and after the movement are differently affected by movement errors. The aim of this thesis was twofold: first, to determine whether or not the pre- and post-movement beta power modulations recruit common neural substrates; second, to better understand the nature of the reflected neural processes. Using an independent component analysis approach, we strongly suggest that oscillatory responses to kinematic errors, observed before and after movement, are underpinned by distinct neural structures, respectively clearly lateralized and medial. Moreover, by contrasting different motor tasks, we show that neither of the two beta activities reflects mechanisms directly related to the output of the motor command.

Dans cette thèse, nous nous intéressons à l'étude d'un modèle dédié à l'exploration et à la structuration d'espaces d'apprentissage sensorimoteur pour des systèmes artificiels. Nous appuyons notre démarche sur les notions de corps et de développement propre, auxquelles se greffe un troisième processus dit motivationnel. Cette forme de curiosité artificielle se base sur le progrès en compétence et repose ainsi sur les contraintes physiques naturelles directement issues de l'encorporation de l'agent. L'objectif de la motivation est de réguler un développement à long terme, dédié à l'apprentissage de nouvelles compétences non prévues par le concepteur. Nous inscrivons nos travaux dans la continuité de l'approche du babillage sensorimoteur dans l'espace des buts, qui consiste à déterminer un ensemble de techniques permettant à un agent de générer, selon une métrique d'intérêt, une configuration sensorielle qu'il va essayer d'atteindre par des actions motrices. Nos contributions viennent améliorer et complexifier un modèle motivationnel existant, en proposant des alternatives au processus de structuration de l'espace d'exploration. Certaines de ces propositions théoriques ont été validées expérimentalement grâce à la plateforme FIMO, que nous avons développée dans cette optique, et qui est disponible en ligne. / In this thesis, we study a motivational model for artificial systems, which aims at exploring and structuring sensorimotor learning spaces. Our approach relies on some essential notions, including the body, the development, and the motivation. This particular kind of artificial curiosity is based on the competence or learning progress, and thus depends on the physical natural constraints originating from the agent's embodiment. We follow the Goal-Babbling Exploration approach which consists in determining a set of techniques allowing an agent to self-generate goals, i.e. sensory configurations, and try to reach them using motor actions. Our contributions improve the SAGG-RIAC motivational model, by proposing alternative ways of structuring the exploration of the goal space. Some of our contributions have been experimentally validated within the FIMO framework we developed to this purpose.

The practice of yoga is an increasingly popularized movement within the West that incorporates the desire for physical fitness, spiritual consciousness, and environmentalism. Emanating from the New Age movement, the popularity of yoga has proliferated as a subculture that seeks to encourage mind–body wellbeing while representing an ethos that assumes environmental responsibility. This thesis examines the techniques of modern yoga and the influence that asana (posture) and meditational relaxation have on the senses and subsequently on environmental awareness and activism. / Includes bibliography. / Thesis (M.A.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Les gens produisent des mouvements spontanés pendant des tâches de raisonnement spatial. Ces mouvements aident-ils à la performance de la tâche? Nous avons étudié le rôle des mouvements spontanés dans l'orientation spatiale en utilisant des tâches de prise de perspective spatiale (PPS) dans lesquelles les participants devaient imaginer un point de vue différent de leur point de vue actuel. Nous nous sommes concentrés sur des perspectives exigeant des rotations mentales de soi - particulièrement difficiles, elles sont grandement facilitées par un mouvement actif, même en l'absence de vision. La contribution motrice à la performance de la tâche pourrait résulter d'un mécanisme prédictif, qui anticipe les conséquences d'une action avant son exécution, comme un modèle d'anticipation interne (Wolpert & Flanagan, 2001), inhibant par la suite l’exécution du mouvement si nécessaire. Les mouvements observés peuvent être des traces visibles de ce processus. En utilisant un système de capture de mouvements, nous avons montré que les rotations de la tête sont géométriquement liées à la PPS : leur direction et amplitude étaient liées à la direction et à l'angle entre les perspectives réelles et imaginée (Exp. 1). Chez les contrôleurs aériens, qualifiés ou apprentis, seule la direction de la rotation de la tête était liée à la PPS, reflétant probablement l'expertise spatiale ainsi que le rôle crucial de la direction dans la rotation mentale (Exp. 2). Dans un environnement virtuel, les rotations de tête spontanées étaient liées à une performance accrue. Cependant, les rotations volontaires, qui imitent celles qui sont produites spontanément, ne facilitent pas la performance de navigation (Exp. 3), mais l'empêchent lorsqu’elles sont contraires à la direction de la rotation virtuelle. Nos résultats suggèrent une contribution motrice spécifique à l'orientation spatiale, compatible avec la prédiction motrice. / People produce spontaneous movements during spatial reasoning tasks. Do they relate to task performance? We investigated the role of spontaneous movements in spatial orientation using spatial perspective-taking (SPT) tasks where participants adopted imaginary perspectives. We focused on imaginary perspectives requiring mental rotations of the self as they are particularly difficult and greatly facilitated by active movement in the absence of vision. Motor contribution to task performance could result from a predictive mechanism, which anticipates the consequences of an action before its execution, such as an internal forward model (Wolpert & Flanagan, 2001), further inhibiting full rotations of the head. Observed movements may be visible traces of this process. Using motion capture, we showed that head movements are geometrically related to SPT: both the direction and amplitude of head rotations were related to the direction and angle between the actual and imagined perspectives (Exp. 1). In air traffic controllers and apprentices, only the direction of head rotation was related to SPT, probably reflecting spatial expertise and its crucial role in mental rotation (Exp. 2). In a virtual environment, spontaneous head rotations were related to increased performance. However voluntary rotations, emulating the spontaneously produced ones, did not facilitate navigation performance (Exp. 3), but hindered it when inconsistent with the direction of virtual rotation. Overall, our findings suggest a specific motor contribution to spatial orientation consistent with motor prediction.

La maladie de Parkinson induit des troubles locomoteurs complexes et variés. Des troubles spécifiques de la marche tels que le " freezing " peuvent survenir ponctuellement. Afin d'améliorer l'accompagnement de ces patients, il est nécessaire d'améliorer notre compréhension de ces situations. Cette thèse vise à caractériser l'activité locomotrice des patients parkinsoniens en situation réelle. Un travail interdisciplinaire a été mené, fondé sur une approche écologique. Quatorze patients ont été suivis. La méthode déployée intégrait le recueil de marqueurs biomécaniques et physiologiques, de l'expérience vécue ainsi que des observations directes. La description de leur expérience a révélé une perception sensori-motrice altérée et une organisation du comportement locomoteur spécifique à l'environnement. Les analyses montrent un schéma d'activation musculaire spécifique, avec notamment une prolongation générale de l'activité des muscles pendant la phase d'appui simple et une augmentation de cocontraction lorsque le pied est en contact au sol. Les résultats de cette analyse intégrée du comportement moteur ont permis de caractériser une typologie de cinq marches et de trois types de " freezing ". De plus, ces observations ont mis en valeur des stratégies utilisé par des patients ainsi qu'un mécanisme d'ajustement neuromusculaire pour augmenter la stabilité de la marche. A long terme, ce travail devrait favoriser 1) la compréhension des bases neurologiques des troubles de la marche ; 2) la prise en charge des patients parkinsoniens ; 3) l'identification des biomarqueurs de la stabilité de la marche ; 4) la spécification des systèmes embarqués du suivi de la marche. / Patients with Parkinson’s disease (PD) experience complex locomotor disturbances. Their walking abilities can be highly variable and specific problems such as freezing of gait may arise during daily life activity. A greater understanding of such difficulties is required in order to develop new therapeutic strategies. This thesis examines the emergence of PD gait patterns during everyday situations. To this end, this study used an interdisciplinary approach drawing upon ecological and embodied perspectives of human activity. The investigation focused upon fourteen PD patients. Data collection methods combined interviews, direct observations and onboard measures of physiological and biomechanical performance. This research identified important changes in patient sensorimotor perception during gait and specific principles regarding the organisation of their movements with respect to the environment. Analysis revealed characteristic changes to lower limb muscle activation patterns, most notably the prolongation of muscle activity during the mid-stance phase; and an increase in cocontraction of agonist-antagonist muscles across the ankle and knee whilst the leg was in contact with the ground. This integrated approach enabled the characterisation of five walking patterns and three types of freezing. These results highlighted patient self-management strategies, and indicated the role of neuromuscular mechanisms for increasing gait stability. Ultimately, these findings may assist to 1) understand the neurological bases of gait dysfunction; 2) enhance PD patient care; 3) identify biomarkers for gait stability and; 4) support the development of ambulatory monitoring technologies.

We have shown that repeated neonatal quinpirole (QUIN; a dopamine D2-like receptor agonist) treatment in rats produces long-lasting supersensitization of dopamine D2 receptors that persists into adulthood but without producing a change in receptor number. The current study was designed to analyze the effects of neonatal QUIN on auditory sensorimotor gating as measured through prepulse inhibition (PPI). Male and female Sprague–Dawley rats were neonatally treated with QUIN (1mg/kg) or saline from postnatal days (P)1–21. At P60, the number of yawns was recorded for a 1h period in response to an acute QUIN (1mg/kg) injection as yawning is a D2-like receptor mediated behavioral event. Five days later, rats began (PPI) behavioral testing in two phases. In phase I, three different prepulse intensities (73, 76, and 82dB) were administered 100-ms before a 115dB pulse on 10 consecutive days. In phase II, three different interstimulus intervals (ISI; 50, 100, and 150ms) were inserted between the 73 or 76dB prepulse and 115dB pulse over 10 consecutive days of testing. A PPI probe trial was administered at the end of each phase after an acute 100μg/kgi.p. injection of QUIN to all animals. Replicating previous work, neonatal QUIN enhanced yawning compared to controls, verifying D2 receptor supersensitization. Regarding PPI, neonatal QUIN resulted in deficits across both phases of testing persistent across all testing days. Probe trial results revealed that acute QUIN treatment resulted in more robust PPI deficits in neonatal QUIN animals, although this deficit was related to prepulse intensity and ISI. These findings provide evidence that neonatal QUIN treatment results in deficits of auditory sensorimotor gating in adulthood as measured through PPI.

Muscle spindles are complex sensory organs that have been strongly implicated in the control and perception of movements. Human muscle spindles in relaxed muscles behave as stretch receptors, responding to the length and velocity of their parent muscles. However, it has been unclear how they discharge during active movements since their discharges are also affected by fusimotor activity and extrafusal contractions. The vast majority of neurophysiological recordings of muscle afferents have been obtained under passive conditions, or active but behaviourally restricted conditions. These restrictions prevent predictions of human muscle afferent activity during purposeful multi-joint movements, naturally occurring during tasks such as hand shaping, grasping or key-pressing. An experimental protocol was therefore developed which allowed recordings of muscle receptor afferent activity using microneurography during unrestrained wrist and digit movements. Along with single afferent discharges, recordings were obtained of electromyographic activity of major forearm muscles and the kinematics of the wrist and digits. This approach allowed investigations of the factors shaping afferent discharge during everyday manual tasks, i.e., block-grasping and pressing sequences of keys, and during active sinusoidal joint movements. The afferents’ ability to encode information concerning the state of the muscle and joint kinematics during these tasks was also assessed. The responses of spindle afferents from load-bearing muscles were approximatelly 90 degrees more phase-advanced than expected on the length of their parent muscles. That is, the discharges of primary muscle spindle afferents were significantly affected by both velocity and acceleration, the discharges of secondary afferents by velocity, and neither afferent type was particularly affected by static muscle length. Accordingly, these afferents failed to encode length, encoded velocity well and acceleration poorly. The representation of muscle length and velocity was, however, significantly improved when the discharge activity of Golgi tendon afferents was taken into consideration along with muscle spindle activity. The discharge of primary afferents during both key-pressing and block-grasping was best correlated to the muscle velocities observed ~100-160 ms in the future. This predictive ability went beyond what could be expected from the spindles’ simultaneous sensitivity to velocity and acceleration, and could thus only be explained by implicating the fusimotor drive. In addition, evidence is presented that the fusimotor control of spindles was contingent on entire movement sequences during the key-pressing task. It is proposed that the phase relationship between the discharge rate of spindle afferents and the length of their parent muscles is load dependent. Moreover, muscle spindles seem to act as forward sensory models of their parent muscle, which makes sensorial feedback control possible despite neural delays.

Chronic neck pain is a widespread problem that causes individual suffering as well as large costs for the society. The knowledge about the pathophysiology is poor and therefore specific diagnosis and causal treatment are rare. Important knowledge for characterization of the disorders has been gained from research on sensorimotor functions in people with neck pain. Moreover, rehabilitation regimes including sensorimotor exercises indicate promising results. The main objectives of this thesis were to extend the knowledge on sensorimotor dysfunctions in chronic neck pain, and to develop a new exercise method for improving sensorimotor functions of the neck. The studies focused on aspects of postural control and movements of the arm and neck. These are vital functions for many activities of daily living. People with chronic (>3 months) neck pain were compared to healthy controls (CON). Neck pain related to trauma was referred to as whiplash associated disorders (WAD), while neck pain without association to trauma was referred to as non-specific (NS). Arm-functioning was assessed in a pointing task. WAD and NS had reduced pointing precision compared to CON. The reduced precision was associated with self-rated difficulties performing neck movements, physical functioning, and in WAD, also pain and balance disturbances. Postural control was assessed in quiet standing on a force platform without vision. The center of pressure signal was decomposed into it’s slow and fast components. WAD and NS were compared to CON. The results revealed an effect of age on the magnitude of the fast sway component, but no effect of group. The magnitude of the slow component was elevated in both WAD and NS. This increase was associated with self-rated balance disturbance, arm-functioning, difficulties to run and sensory alterations in WAD, while in NS, the increase in the slow sway component was associated with concurrent low back pain. Neck movements were assessed in a cervical axial rotation test with maximal speed. In total 8 variables representing basic kinematics, including variables reflecting movement smoothness and conjunct motions were calculated. NS were compared to CON. Linear discriminant modelling indicated Peak Speed and conjunct motions as significant classification variables that together had a sensitivity of 76.3% and specificity of 77.6%. Retest reliability was good for Peak Speed but poor for the measure of conjunct motions. Peak Speed was slower in NS compared to CON, and even slower in a sub-group of NS with concurrent low back pain. Reduced Peak Speed was associated with self-rated difficulties performing neck movements, car driving, running, sleeping disturbances and pain. The clinical applicability of a novel method for neck coordination exercise was assessed in a pilot study on persons with NS. The results supported the applicability and indicated positive effects of the exercise: reduced postural sway in quiet standing and increased smoothness in cervical rotations. Indications on improvement in self-rated disability and fear of movement were seen at six months follow up. In conclusion, sensorimotor functions can be altered in chronic neck pain, particularly in neck disorders with concurrent low back pain and WAD. The discriminative ability and clinical validity displayed in pointing precision, postural sway and cervical axial rotation speed imply that such tests can be valuable tools in the assessment of chronic neck pain patients, and for selecting and evaluating treatment interventions. Indications of improvements seen in the pilot-study support a future RCT.