Dissertations / Theses on the topic 'Elbow movement'

Projeto de Graduação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciado em Fisioterapia
Objetivo: Determinar a efetividade da mobilização com movimento (MCM) na epicondilite lateral (EL) do cotovelo. Metodologia: Pesquisa computadorizada nas bases de dados PubMed / Medline, PEDro, Scielo e Lilacs para identificar estudos randomizados controlados que avaliam a efetividade da MCM na EL. Resultados: Nesta revisão foram incluídos 6 estudos envolvendo 194 pacientes, com classificação metodológica de média aritmética 5,17 na escala de PEDro. Dos estudos incluídos nesta revisão verificou-se que 3 analisaram os efeitos da MCM em conjunto com um tratamento de fisioterapia e 3 como uma técnica de fisioterapia isolada. Todos os estudos analisados obtiveram resultados satisfatórios, a curto e médio prazo, em termos de alívio da dor, força de preensão e / ou funcionalidade. Conclusão: A MCM parece ser eficaz a curto e médio prazo no tratamento da LE.
Objective: To determine the effectiveness of mobilization with movement (MWM) in elbow lateral epicondylitis (LE). Methodology: Research on computerized databases PubMed / Medline, PEDro, Scielo and Lilacs to identify randomized controlled trials that evaluates the effectiveness of MWM in LE. Results: This review included 6 studies involving 194 patients, with arithmetic mean methodology classification of 5.17 on the PEDro scale. From the studies included in this review it was found that 3 analyzed the effects of MWM included in a physiotherapy treatment and 3 as an isolated physiotherapeutic technique. All the studies analyzed have shown satisfactory results, in short and medium term, in terms of pain relief, grip strength and / or functionality. Conclusion: MWM seems to be effective in the short and medium term in the treatment of LE.
N/A

The present study quantifies electromyographic variables in one and two degree of freedom elbow movements involving flexion/extension and pronation/supination, in order to understand the associated central commands. Agonist burst magnitude varied with motion in a second degree of freedom for some muscles but not for others. In movements for which a biarticular muscle acted as agonist in two degrees of freedom, agonist burst magnitudes were approximately the sum of the magnitudes in the component movements. Agonist burst magnitude varied with motion in a second degree of freedom for some, but not all, monoarticular muscles. When biarticular muscles acted as agonist in one degree of freedom and antagonist in the other, the muscle often displayed both components simultaneously. The additivity of EMG burst magnitudes in two degree of freedom movements and the presence of both agonist and antagonist bursts in a muscle suggest that central commands associated with motion in individual degrees of freedom are superimposed in producing two degree of freedom movements.

Empirical and modelling studies are reported which explore ways in which the central nervous system might consider musculo-skeletal geometry when generating commands for single degree of freedom elbow flexion and extension movements. In a series of experiments it is shown that subjects do not perform rapid, goal-directed flexion and extension movements equally accurately in different parts of the elbow's workspace. In these experiments, movements of 10, 20 and 30 degrees in amplitude were tested using up to five different initial elbow angles. When performing flexions, subjects tended to overshoot targets when starting from extended positions, to undershoot targets when starting from more flexed positions, and to perform relatively accurate movements when starting from the centre of the workspace. Final position accuracy was more variable for extensions. When reliable differences existed for extensions, subjects tended to produce a pattern of results opposite to that of flexions: subjects overshot targets when starting from flexed positions and undershot targets when starting from more extended positions. A model of elbow movement based on the $ lambda$ version of the equilibrium-point hypothesis was used to assess the extent to which the pattern of errors obtained in the empirical studies could be reproduced by a control scheme that does not adjust commands in response to changing musculo-skeletal geometry, but rather uses one single invariant command throughout the workspace. The motivation for testing the invariant command notion was to explore the possibility that motion planning might be achieved without an explicit representation of musculo-skeletal geometry. Predicted patterns of final position errors across the workspace matched empirically obtained error patterns for flexions, but the model performed less well when predicting the pattern of errors observed for extension movements.

Understanding the control strategies that underlie multijoint limb movements is important to researchers in motor control, robotics, and medicine. Due to dynamic interactions between limb segments, choosing appropriate muscle activations for initiating multijoint arm movements is a complex problem, and the rules by which the nervous system makes such choices are not yet understood. The aim of the dissertation studies was to evaluate some proposed initiation rules based on their ability to correctly predict which shoulder and elbow muscles initiated planar, two-joint arm movements in various directions. Kinematic and electromyographic data were collected from thirteen subjects during pointing movements involving shoulder and elbow rotations in the horizontal plane. One of the rules tested, which is based on statics, predicted that the initial muscle activity at each joint is chosen such that the hand exerts an initial force in the direction of the target, while another rule, based on dynamics, predicted initial muscle activity such that the initial acceleration of the hand is directed toward the target. For both rules, the data contradict the predicted initial shoulder muscle activity for certain movement directions. Moreover, the effects of added inertial loads predicted by the latter rule were not observed when a 1.8 kg mass was added to the limb. The results indicated, however, that empirically derived rules, based on ψ, the target direction relative to the distal segment, could predict which muscles would be chosen to initiate movement in a given direction. Furthermore, the relative timing and magnitude of initial muscle activity at the shoulder and elbow varied systematically with ψ. Thus, the target direction relative to the forearm may be an important variable in determining initial muscle activations for multijoint arm movements. These findings suggest a control scheme for movement initiation in which simple rules suffice to launch the hand in the approximate direction of the target by first specifying a basic motor output pattern, then modulating the relative timing and magnitude of that pattern.

One concept central to theories of multijoint control concerns the selection of muscles for the appropriate joint motion. For multijoint movements, a given muscle torque at an individual joint can lead to flexion, extension, or very little motion, since mechanical effects coming from other segments interact with muscle torque. This study quantified the contribution of muscle torque to initial joint motion for horizontal arm movements throughout the workspace. Previous studies of arm mechanics have been limited to a few movements or have focused on one joint. In contrast, this study reports data for both the shoulder and elbow joints. Moreover, a large number of movements were used for which direction, excursion, and distance were manipulated. Using high speed video recordings and techniques of inverse dynamics, a ratio of muscle torque to total torque was computed for each movement as a measure of contribution of muscle torque to joint acceleration. One consistent finding was that the muscle torque contribution consistently differed between the shoulder and elbow for most of the workspace. At one joint, muscle torque directly contributed to acceleration with negligible interaction torque ('direct' muscle torque contribution), thus the joint appeared to act as the launcher of the arm. At the other joint, both muscle and interaction torques contributed to joint acceleration ('complex' contribution), thus the joint appeared to be responding to mechanical effects from motion of the launcher. This contrast between joints may provide a simplifying feature for multijoint arm control. Specifically, only one of the two joints has complex mechanics, while the other joint, surprisingly, has simplified mechanics similar to a single joint in isolation. Movements in this study also demonstrated a three fold covariance (muscle torque contribution, movement direction, and the relative excursions of the shoulder and elbow) regardless of distance. A covariance of movement features, historically viewed as a confound, may provide a further simplification for arm control by reducing the unknowns; namely, the muscle torque contribution is associated with a resultant direction and joint excursions, or a direction or set of excursions is achieved by the associated muscle torque contribution.

碩士
國立成功大學
機械工程學系
89
Stroke patients with upper motor unit lesion usually have observable muscle weakness in their affected side due to the abnormal efficiency of muscle contraction. The goal of this thesis is to enhance a stroke patient's muscle strength by adopting a control system which can actively provide the elbow joint with an appropriate torque based on EMG signals taken from triceps and biceps. By using this EMG controlled system the stroke patient's motor control capability for elbow joints can be improved and reduce the negative effects induced by muscle wealness. Due to the discrepancy between contraction efficiencies of triceps and biceps, the ratio of unilateral EMG signals to elbow torque resulting from isometric contraction under various elbow angles are employed to construct a gain mapping matrix for system control. Co-activation within extensor and flexor can increase the stiffness of elbow joint and thus stabilize the motion of elbow. Therefore, in the control system, a nonlinear damping that has a physiological rationale is adopted to simulate the effect of co-activation. The coefficient of the nonlinear damping is determined by summing EMG signals of triceps and biceps. Since the wave form of control signals (i.e., EMG signals) resembles Gaussian distribution, the motor outputs a non-smooth torque trajectory to elbow joint which makes the subjects hard to accept the control system. Hence for obtaining a smooth torque trajectory, an adaptive filter is employed to automatically tune the bandwidth of the man-machine control system to within a permissible range. Two sets of experiments are performed. In the first set the subjects are asked to move their forearm sgainst to a constant load from point to point while they follow a trajectory on the monitor. In the second set, the subjects are asked to perform a lift-hold-depose-hold movement against to a constant load too. Statistical analyses of the experiment results revealed the external torque can significantly improve the muscle power but cannot influence the tracking performance and nonlinear damping combined with the adaptive filter can stabilize the man-machine system and yield a much smoother movement.

碩士
國立臺灣體育學院
體育研究所
98
The purpose of this study was to investigate the learning effect of elbow flexion movement through the various manipulations of the reduced knowledge of results (KR) for adolescent. Fifty voluntary participants, 23 female and 27 male (mean age = 14.5 years), were assigned randomly to 100 percent KR frequency group, 20 percent KR frequency group, 10 percent KR frequency group, performance-based bandwidth group, and the control group of performance-based bandwidth. All participants were asked to operate and to learn the Biometrics E-Link system for 57 degrees of elbow flexion. After 100 trails of acquisition, every participant was assessed the learning effects by immediate retention test, delay retention test, 41 degrees of elbow flexion immediate transfer test, and 41 degrees of elbow flexion delay transfer test. The angle of elbow flexion was acquired by Biometrics E-Link system and was used to calculate the error scores: constant error, absolute error, total variability, variable error, and coefficient of variable error. 5 (group) × 2 (test) Mixed-design two way ANOVA and Duncan post-hoc comparison were used to test the statistical difference. The results of retention test showed there was no groups difference for variable error (p > .05), but the immediate retention test was lower than delay retention test (p < .05). The constant error of 100 percent KR frequency group was the largest in immediate retention test (p < .05), but there were no group difference in delay retention test (p > .05). There were no group differences for transfer test (p > .05). It indicated that high KR frequency was the performance variable for the adolescent to acquisition the skill of elbow flexion. For the techniques of reduce augmented feedback frequency, the constant to provide KR (the control group of performance-based bandwidth and the groups of lower KR frequency) and the fading technique (performance-based bandwidth group) were benefit for motor learning.

Thesis (M.S.)--University of Wisconsin--Madison, 1987.
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碩士
國立成功大學
機械工程學系
86
In this study, an elbow vooluntary movement model is established tto find the difference of motor control bettween normal subjects and patients. The tonic reflex in normal model is increased to simulate the effect of spasticity on stroke patients movement control. Base on Hogan''s model and the model, a flexor model and an extensor model are built to decompose the net torque occurred at the elbow joint. the mechanism of Hyperttonia can be quantified not only by the increasing of anttagonist activation in Hogan''s model, but also by the constraint in reciprocal command and decreasing threshold in model. in the rapid elbow extension tests we found that due to the lost of inhibition. The first antagonist bursts of patients are earlier thanthat of normals and patients'' trajectories can not achieve satisfied movements. an optimall controller is utilized to model different control strategies of the hierarchical central neural system. our experimental and simulation results indicate that by properly modulating movement commands, the neuroomotor system can track the desired trajectories. the reverse shifting of reciprocal commands to the elbow displacements can explain that by changing activation ratio and by imposing constraints on the threshold. the models developed in this work can be used to simulate the motor control of stroke patients.

M.Tech. (Chiropractic)
The purpose of this study was to establish whether cervical spinal manipulation induces an appreciable and sustainable alteration in muscle torque performance regarding the elbow flexor muscles. Forty asymptomatic individuals participated in this study. Twenty individuals were randomly assigned to either an experimental or control group. Participants selected had to be between 18 and 40 years of age and had to present with cervical motion restrictions involving the fourth to sixth cervical vertebrae, as determined by motion palpation assessment. Participants were randomly recruited from the University of Johannesburg and surrounding areas, based on their response to information pamphlets and word of mouth. The experimental group received cervical spinal manipulation involving the lower cervical segments on three separate occasions. The control group received no intervention. Elbow flexion torque assessments were conducted using the Biodex System 3, isokinetic dynamometer. Two assessments were done prior to intervention and one test following one week of intervention, to ascertain whether cervical manipulation can provoke a sustainable improvement in elbow flexion performance. Cervical range of motion (CROM) assessment was used as a secondary objective evaluation to assess the effectiveness of the manipulation procedures, considering that improvement in cervical range of motion following spinal manipulation is well documented. Minimal improvement in elbow flexion torque involving both arms was observed in the experimental group following one weeks‟ intervention however, no statistical significance was reported. Gender relations regarding the elbow flexion torque performances revealed and improvement in strength in the male participants and a reduction in performance in the female participants. Statistical significance was reported although the significance regarding intervention remains unclear. No sustainable improvement in elbow flexion torque was revealed following spinal manipulative therapy and therefore does not provide conclusive evidence to substantiate the motor neuron excitability theory. The contradictory results with regards to the female participants bring into context an indefinite and unfamiliar neuromusculoskeletal paradigm which requires additional research to clarify these anomalous findings.

The ulnar collateral ligament (UCL) is the primary restraint against valgus forces at the elbow. This structure cannot support the entire load placed upon the medial elbow during overhand throwing motions such as pitching a baseball. In this study we measured the contributions that different muscle groups make to the stability of the medial elbow, under conditions intended to reproduce the loads during pitching by varying the forearm position and loading conditions. We also evaluated the strength of the elbow musculature for the possibility of a training effect in the dominant arm of 11 male high school baseball pitchers. We collected surface EMG data in the two forearm positions to determine if the different positions used in various pitches have an effect on muscular action. We also tested an isometric and dissipative loading condition to determine if the muscles activity was load reactive. The four muscle groups tested were the flexor-pronator group (FP), the extensor-supinator group (ES), the tricep brachii (TB), and the pectoralis major (PM). We found significantly (p-value=0.001) higher peak activity levels of the flexor-pronator group in the neutral forearm position (79.4% MVIC �� 27.0% MVIC full trial peak, 30.8% MVIC �� 20.8% MVIC initial l50ms peak following activation) when compared to the supinated position (55.5% MVIC �� 29.6% MVIC full trial peak, 16.9% MVIC �� 14.8% MVIC initial l50ms peak following activation), which may explain the link between breaking pitches and medial elbow injury. We found an increase (p-value=0.001) in force output of the dominant arm (49.3 N/kg �� 12.5 N/kg) over the non-dominant arm (38.1 N/kg �� 11.0 N/kg). This finding is attributed to a training effect, which assists in protecting the elbow. These findings help provide baseline muscle activity information on protection of the medial soft tissue structures of the elbow.
Graduation date: 2004

Dans cette thèse, nous abordons le contrôle moteur du mouvement du coude à travers deux approches expérimentales : une première étude psychophysique a été effectuée chez les sujets humains, et une seconde implique des enregistrements neurophysiologiques chez le singe. Nous avons recensé plusieurs aspects non résolus jusqu’à présent dans l’apprentissage moteur, particulièrement concernant l’interférence survenant lors de l’adaptation à deux ou plusieurs champs de force anti-corrélés. Nous avons conçu un paradigme où des stimuli de couleur aident les sujets à prédire la nature du champ de force externe actuel avant qu’ils ne l’expérimentent physiquement durant des mouvements d’atteinte. Ces connaissances contextuelles faciliteraient l’adaptation à des champs de forces en diminuant l’interférence. Selon le modèle computationnel de l’apprentissage moteur MOSAIC (MOdular Selection And Identification model for Control), les stimuli de couleur aident les sujets à former « un modèle interne » de chaque champ de forces, à s’en rappeler et à faire la transition entre deux champs de force différents, sans interférence. Dans l’expérience psychophysique, quatre groupes de sujets humains ont exécuté des mouvements de flexion/extension du coude contre deux champs de forces. Chaque force visqueuse était associée à une couleur de l’écran de l’ordinateur et les deux forces étaient anti-corrélées : une force résistante (Vr) a été associée à la couleur rouge de l’écran et l’autre, assistante (Va), à la couleur verte de l’écran. Les deux premiers groupes de sujets étaient des groupes témoins : la couleur de l’écran changeait à chaque bloc de 4 essais, tandis que le champ de force ne changeait pas. Les sujets du groupe témoin Va ne rencontraient que la force assistante Va et les sujets du groupe témoin Vr performaient leurs mouvements uniquement contre une force résistante Vr. Ainsi, dans ces deux groupes témoins, les stimuli de couleur n’étaient pas pertinents pour adapter le mouvement et les sujets ne s’adaptaient qu’à une seule force (Va ou Vr). Dans les deux groupes expérimentaux, cependant, les sujets expérimentaient deux champs de forces différents dans les différents blocs d’essais (4 par bloc), associés à ces couleurs. Dans le premier groupe expérimental (groupe « indice certain », IC), la relation entre le champ de force et le stimulus (couleur de l’écran) était constante. La couleur rouge signalait toujours la force Vr tandis que la force Va était signalée par la couleur verte. L’adaptation aux deux forces anti-corrélées pour le groupe IC s’est avérée significative au cours des 10 jours d’entraînement et leurs mouvements étaient presque aussi bien ajustés que ceux des deux groupes témoins qui n’avaient expérimenté qu’une seule des deux forces. De plus, les sujets du groupe IC ont rapidement démontré des changements adaptatifs prédictifs dans leurs sorties motrices à chaque changement de couleur de l’écran, et ceci même durant leur première journée d’entraînement. Ceci démontre qu’ils pouvaient utiliser les stimuli de couleur afin de se rappeler de la commande motrice adéquate. Dans le deuxième groupe expérimental, la couleur de l’écran changeait régulièrement de vert à rouge à chaque transition de blocs d’essais, mais le changement des champs de forces était randomisé par rapport aux changements de couleur (groupe « indice-incertain », II). Ces sujets ont pris plus de temps à s’adapter aux champs de forces que les 3 autres groupes et ne pouvaient pas utiliser les stimuli de couleurs, qui n’étaient pas fiables puisque non systématiquement reliés aux champs de forces, pour faire des changements prédictifs dans leurs sorties motrices. Toutefois, tous les sujets de ce groupe ont développé une stratégie ingénieuse leur permettant d’émettre une réponse motrice « par défaut » afin de palper ou de sentir le type de la force qu’ils allaient rencontrer dans le premier essai de chaque bloc, à chaque changement de couleur. En effet, ils utilisaient la rétroaction proprioceptive liée à la nature du champ de force afin de prédire la sortie motrice appropriée pour les essais qui suivent, jusqu’au prochain changement de couleur d’écran qui signifiait la possibilité de changement de force. Cette stratégie était efficace puisque la force demeurait la même dans chaque bloc, pendant lequel la couleur de l’écran restait inchangée. Cette étude a démontré que les sujets du groupe II étaient capables d’utiliser les stimuli de couleur pour extraire des informations implicites et explicites nécessaires à la réalisation des mouvements, et qu’ils pouvaient utiliser ces informations pour diminuer l’interférence lors de l’adaptation aux forces anti-corrélées. Les résultats de cette première étude nous ont encouragés à étudier les mécanismes permettant aux sujets de se rappeler d’habiletés motrices multiples jumelées à des stimuli contextuels de couleur. Dans le cadre de notre deuxième étude, nos expériences ont été effectuées au niveau neuronal chez le singe. Notre but était alors d’élucider à quel point les neurones du cortex moteur primaire (M1) peuvent contribuer à la compensation d’un large éventail de différentes forces externes durant un mouvement de flexion/extension du coude. Par cette étude, nous avons testé l’hypothèse liée au modèle MOSAIC, selon laquelle il existe plusieurs modules contrôleurs dans le cervelet qui peuvent prédire chaque contexte et produire un signal de sortie motrice approprié pour un nombre restreint de conditions. Selon ce modèle, les neurones de M1 recevraient des entrées de la part de plusieurs contrôleurs cérébelleux spécialisés et montreraient ensuite une modulation appropriée de la réponse pour une large variété de conditions. Nous avons entraîné deux singes à adapter leurs mouvements de flexion/extension du coude dans le cadre de 5 champs de force différents : un champ nul ne présentant aucune perturbation, deux forces visqueuses anti-corrélées (assistante et résistante) qui dépendaient de la vitesse du mouvement et qui ressemblaient à celles utilisées dans notre étude psychophysique chez l’homme, une force élastique résistante qui dépendait de la position de l’articulation du coude et, finalement, un champ viscoélastique comportant une sommation linéaire de la force élastique et de la force visqueuse. Chaque champ de force était couplé à une couleur d’écran de l’ordinateur, donc nous avions un total de 5 couleurs différentes associées chacune à un champ de force (relation fixe). Les singes étaient bien adaptés aux 5 conditions de champs de forces et utilisaient les stimuli contextuels de couleur pour se rappeler de la sortie motrice appropriée au contexte de forces associé à chaque couleur, prédisant ainsi leur sortie motrice avant de sentir les effets du champ de force. Les enregistrements d’EMG ont permis d’éliminer la possibilité de co-contractions sous-tendant ces adaptations, étant donné que le patron des EMG était approprié pour compenser chaque condition de champ de force. En parallèle, les neurones de M1 ont montré des changements systématiques dans leurs activités, sur le plan unitaire et populationnel, dans chaque condition de champ de force, signalant les changements requis dans la direction, l’amplitude et le décours temporel de la sortie de force musculaire nécessaire pour compenser les 5 conditions de champs de force. Les changements dans le patron de réponse pour chaque champ de force étaient assez cohérents entre les divers neurones de M1, ce qui suggère que la plupart des neurones de M1 contribuent à la compensation de toutes les conditions de champs de force, conformément aux prédictions du modèle MOSAIC. Aussi, cette modulation de l’activité neuronale ne supporte pas l’hypothèse d’une organisation fortement modulaire de M1.
In this thesis, we addressed motor control by two experimental approaches: psychophysical studies in human subjects and neurophysiological recordings in non-human primates. We identified unresolved issues concerning interference in motor learning during adaptation of subjects to two or more anti-correlated force fields. We designed paradigms in which arbitrary color stimuli provided contextual cues that allowed subjects to predict the nature of impending external force fields before encountering them physically during arm movements. This contextual knowledge helped to facilitate adaptation to the force fields by reducing this interference. According to one computational model of motor learning (MOdular Selection And Identification model for Control; MOSAIC), the color context cues made it easier for subjects to build “internal models” of each force field, to recall them and to switch between them with minimal interference. In our first experiment, four groups of human subjects performed elbow flexion/extension movements against two anti-correlated viscous force fields. We combined two different colors for the computer monitor background with two forces: resistive (Vr) and assistive (Va). The first two groups were control subjects. In those subjects, the color of the computer monitor changed at regular intervals but the force field remained constant; Vr was presented to the first group while the second group only experienced Va. As a result, the color cues were irrelevant in the two control groups. All control subjects adapted well to the single experienced force field (Vr or Va). In the two experimental groups, in contrast, the anti-correlated force fields and the monitor colors changed repeatedly between short blocks of trials. In the first experimental group (Reliable-cue subjects), there was a consistent relationship between the force and the stimulus (color of the monitor) - the red colour always signalled the resistive force while the green colour always signalled the assistive force. Adaptation to the two anti-correlated forces for the Reliable-cue group was significant during 10 days of training and almost as good as in the Irrelevant-cue groups who only experienced one of the two force fields. Furthermore, the Reliable-cue subjects quickly demonstrated predictive adaptive changes in their motor output whenever the monitor color changed, even during their first day of training, showing that they could use the reliable color context cues to recall the appropriate motor skills. In contrast, the monitor color also changed regularly between red and green in the second experimental group, but the force fields were not consistently associated with the color cue (Unreliable-cue group). These subjects took longer to adapt to the two force fields than the other three groups, and could not use the unreliable color cue change to make predictive changes to their motor output. Nevertheless, all Unreliable-cue subjects developed an ingenious strategy of making a specific “default” arm movement to probe the type of force field they would encounter in the first trial after the monitor color changed and used the proprioceptive feedback about the nature of the field to make appropriate predictive changes to their motor output for the next few trials, until the monitor color changed again, signifying the possibility of a change in force fields. This strategy was effective since the force remained constant in each short block of trials while the monitor color remained unchanged. This showed that the Unreliable-cue subjects were able to extract implicit and explicit information about the structure of the task from the color stimuli and use that knowledge to reduce interference when adapting to anti-correlated forces. The results of this first study encouraged us to advance our understanding of how subjects can recall multiple motor skills coupled to color context stimuli can be recalled, and how this phenomenon can be reflected by the neuronal activity in monkeys. Our aim was to elucidate how neurons of primary motor cortex (M1) can contribute to adaptive compensation for a wide range of different external forces during single-joint elbow flexion/extension movements. At the same time, we aimed to test the hypothesis evoked in the MOSAIC model, whereby multiple controller modules located in the cerebellum may predict each context and produce appropriate adaptive output signals for a small range of task conditions. Also, according to this hypothesis, M1 neurons may receive inputs from many specialized cerebellar controllers and show appropriate response modulations for a wide range of task conditions. We trained two monkeys to adapt their flexion/extension elbow movements against 5 different force-field conditions: null field without any external force disturbance, two anti-correlated viscous forces (assistive and resistive), which depended on movement speed and resembled that used in the human psychophysical study, a resistive elastic force which depended on elbow-joint position and finally, a visco-elastic field that was the linear sum of the elastic and viscous forces field. Each force field was reliably coupled to 5 different computer monitor background colors. The monkeys properly adapted to the 5 different force-field conditions and used the color context cues to recall the corresponding motor skill for the force field associated with each color, so that they could make predictive changes to their motor output before they physically encountered the force fields. EMG recordings eliminated the possibility that a co-contraction strategy was used by the monkeys to adapt to the force fields, since the EMG patterns were appropriate to compensate for each force-field condition. In parallel, M1 neurons showed systematic changes in their activity at the single-neuron and population level in each force-field condition that could signal the required changes in the direction, magnitude and time course of muscle force output required to compensate for the 5 force-field conditions. The patterns of response changes in each force field were consistent enough across M1 neurons to suggest that most M1 neurons contributed to the compensation for all force field conditions, in line with the predictions of the MOSAIC model. Also, these response changes do not support a strongly modular organization for M1.

Thesis (M.S.)--University of Wisconsin--Madison, 1989.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 45-48 leaves).