<p> Although most muscle spindle investigations have used the cat model and mvasiVe surgical measurement techniques, several investigators have used microneurography to record from the Ia and II fibres in humans during tendon vibration. In these studies the muscle spindle primary (Ia) endings are stimulated using transverse vibration of the tendon at reflex sub-threshold amplitudes. Others have used low amplitude vibration and the H-reflex (monosynaptic electrical response) to determine reflex properties during both agonist and antagonist voluntary contractions. Both of these methods explore only certain parts of the monosynaptic reflex arc; microneurography focus on the properties and firing characteristics of the muscle spindles themselves, whereas the H-reflex response to vibration is a representation of the response of the spinal cord as well as the muscle spindles. </p> <p> In the past we have developed a PC based instrument that uses Lab VIEW and a linear servomotor to study tendon reflex properties by recording H-reflexes (or stretch reflexes for mechanical stimuli) from single tendon taps or electrical stimuli to the afferent nerve. In this thesis we describe a further development of this system to provide precise vibrations of the tendon at up to 55 Hz with amplitudes up to 4 mm. The resultant vibration stretch reflex train is extracted from 2 major background noise sources, 60 Hz power line noise, and vibration artifact noise, of the EMG recording via phase coherent subtractive filtering. </p> <p> To demonstrate the versatility and efficacy of this system in studying the monosynaptic reflex arc, test results from several pilot studies are presented, using the system to vibrate the human distal flexor carpi radialis tendon: (i) whether stretch reflexes could be entrained with high frequency vibration, as contrary to H-reflexes, (ii) whether the responses were affected by low levels of agonist or antagonist contraction, in agreement with the existing pool of work on the subject using the H-reflex, (iii) whether a separation of the Ia (primary) and II (secondary) ending pathways is observable as individual but delayed responses at low vibration frequencies due to different activation characteristics, and axon diameters, of each ending. Possible physiological mechanisms that explain the resultant behaviour are also discussed. </p> / Thesis / Master of Applied Science (MASc)

The current study evaluated whether robotic guidance can influence movement planning and/or the use of online proprioceptive feedback. Participants were divided into three groups wherein they practiced an aiming task unassisted or via a robotic device that led them through a trajectory with an asymmetric or symmetric velocity profile. Baseline performance was measured prior to training and a post-test included control and tendon vibration trials. Temporal, spatial, and kinematic variables were used to assess planning and online control mechanisms. Results indicated that tendon vibration altered the way individuals planned their movements and used online sensory feedback. Robotic-guided groups appeared to use online feedback to a lesser extent than the unassisted group during tendon vibration trials, based on kinematic data. Individuals may become less inclined to use erroneous proprioceptive feedback following robotic guidance, supporting the potential benefit of robotics in neuro-motor rehabilitation for those with proprioceptive deficits.

The current study evaluated whether robotic guidance can influence movement planning and/or the use of online proprioceptive feedback. Participants were divided into three groups wherein they practiced an aiming task unassisted or via a robotic device that led them through a trajectory with an asymmetric or symmetric velocity profile. Baseline performance was measured prior to training and a post-test included control and tendon vibration trials. Temporal, spatial, and kinematic variables were used to assess planning and online control mechanisms. Results indicated that tendon vibration altered the way individuals planned their movements and used online sensory feedback. Robotic-guided groups appeared to use online feedback to a lesser extent than the unassisted group during tendon vibration trials, based on kinematic data. Individuals may become less inclined to use erroneous proprioceptive feedback following robotic guidance, supporting the potential benefit of robotics in neuro-motor rehabilitation for those with proprioceptive deficits.

Nos travaux portent sur les mécanismes nerveux qui sous-tendent la perception de notre corps en mouvement. Chacune de nos actions est caractérisée par l'intention motrice qui en est à l'origine et par le feedback multi-modalitaire que son exécution évoque. Dans ce cadre, nous avons formalisé le codage proprioceptif du mouvement et nous avons exploré deux types d'images motrices et leur interaction perceptive à travers l'étude des mouvements imaginés et des illusions kinesthésiques.Sur la base de données neurosensorielles, nous avons contribué à développer une méthode « propriomimétique » inspirée du modèle vectoriel de population permettant de prédire les patterns proprioceptifs afférents évoqués lors de mouvements complexes. Ces patterns modélisés ont ensuite été utilisés pour activer les voies de la proprioception musculaire chez des sujets immobiles grâce à la méthode des vibrations tendineuses. / This thesis deals with the neural mechanisms involved in body movement perception. We contributed to developing a "propriomimetic" method based on neurosensory data and drawn from the population vector model for predicting the afferent proprioceptive patterns evoked during complex movements.The main contribution of this work is that it extends the scope of the method to include the whole set of possible human actions by showing that it can be used to accurately predict the proprioceptive patterns and to generate the kinaesthetic experiences associated with movements involving one or more joints, performed in 2- or 3-dimensional space, regardless of which muscles are involved.Other motor images were intentionally generated by the subjects in subsequent experiments and combined with those imposed by the vibratory stimulation. The results obtained here show that the images of both kinds were completely integrated when evoked simultaneously and that they gave rise to a unique and original perceptual experience, in which their spatio-temporal characteristics were combined. From the theoretical point of view, these findings confirm that proprioceptive afferents play an important role, along with the motor intention itself, in the elaboration of kinaesthetic perception. From the clinical point of view, the possibility of evoking motor images quite "naturally" using the method presented here to activate the peripheral receptors and/or the command centers, and thus the whole sensorimotor loop in the absence of any real movements, opens some promising perspectives for rehabilitation purposes.