Dissertations / Theses on the topic 'Parkinsonism and motor control'

The basal ganglia (BG) is a complex set of heavily interconnected nuclei located in the central part of the brain that receives inputs from the several areas of the cortex and projects via the thalamus back to the prefrontal and motor cortical areas. Despite playing a significant part in multiple brain functions, the physiology of the BG and associated disorders like dystonia remain poorly understood. Dystonia is a devastating condition characterized by ineffective, twisting movements, prolonged co-contractions and contorted postures. Evidences suggest that it occurs due to abnormal discharge patterning in BG-thalamocortocal (BGTC) circuitry. The central purpose of this study was to understand the electrophysiology of BGTC circuitry and its role in motor control and dystonia. Toward this goal, an advanced multi-target multi-unit recording and analysis system was utilized, which allows simultaneous collection and analysis of multiple neuronal units from multiple brain nuclei. Over the cause of this work, neuronal data from the globus pallidus (GP), subthalamic nucleus (STN), entopenduncular nucleus (EP), pallidal receiving thalamus (VL) and motor cortex (MC) was collected from normal, lesioned and dystonic rats under awake, head restrained conditions. The results have shown that the neuronal population in BG nuclei (GP, STN and EP) were characterized by a dichotomy of firing patterns in normal rats which remains preserved in dystonic rats. Unlike normals, neurons in dystonic rat exhibit reduced mean firing rate, increased irregularity and burstiness at resting state. The chaotic changes that occurs in BG leads to inadequate hyperpolarization levels within the VL thalamic neurons resulting in a shift from the normal bursting mode to an abnormal tonic firing pattern. During movement, the dystonic EP generates abnormally synchronized and elongated burst duration which further corrupts the VL motor signals. It was finally concluded that the loss of specificity and temporal misalignment between motor neurons leads to corrupted signaling to the muscles resulting in dystonic behavior. Furthermore, this study reveals the importance of EP output in controlling firing modes occurring in the VL thalamus.

Parkinson’s disease is a neurodegenerative disorder due to the death of the dopaminergic neurons of the substantia nigra of the basal ganglia. The process that leads to these neural alterations is still unknown. Parkinson’s disease affects most of all the motor sphere, with a wide array of impairment such as bradykinesia, akinesia, tremor, postural instability and singular phenomena such as freezing of gait. Moreover, in the last few years the fact that the degeneration in the basal ganglia circuitry induces not only motor but also cognitive alterations, not necessarily implicating dementia, and that dopamine loss induces also further implications due to dopamine-driven synaptic plasticity got more attention. At the present moment, no neuroprotective treatment is available, and even if dopamine-replacement therapies as well as electrical deep brain stimulation are able to improve the life conditions of the patients, they often present side effects on the long term, and cannot recover the neural loss, which instead continues to advance. In the present thesis both motor and cognitive aspects of Parkinson’s disease and basal ganglia circuitry were investigated, at first focusing on Parkinson’s disease sensory and balance issues by means of a new instrumented method based on inertial sensor to provide further information about postural control and postural strategies used to attain balance, then applying this newly developed approach to assess balance control in mild and severe patients, both ON and OFF levodopa replacement. Given the inability of levodopa to recover balance issues and the new physiological findings than underline the importance in Parkinson’s disease of non-dopaminergic neurotransmitters, it was therefore developed an original computational model focusing on acetylcholine, the most promising neurotransmitter according to physiology, and its role in synaptic plasticity. The rationale of this thesis is that a multidisciplinary approach could gain insight into Parkinson’s disease features still unresolved.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2008.
Includes bibliographical references.
Parkinson's disease (PD) is a primarily motor disorder which affects at least half a million people in the US alone. Deep brain stimulation (DBS) is a neurosurgical intervention by which neural structures are stimulated electrically by an implanted pacemaker. It has become the treatment of choice for PD, when not adequately controlled by drug therapy. We introduced a novel robotic platform for the study of the effects of DBS on motor control in PD. Subjects performed discrete wrist movements with and without a force field. We found preliminary indication that motor learning may be taking place with stimulation, and demonstrated how robotic testing can augment existing clinical tools in evaluation of the disease. To study the effect of stimulation on movement frequency, we employed a rhythmic task that required movements of the elbow to remain within a closed shape on a phase plane. Three closed shapes required varying frequency/amplitude combinations of elbow movement. The task was performed with and without visual feedback. Analysis of data from the healthy control subjects revealed a non-monotonic relation between accuracy on the phase plane and movement speed. Further kinematic analyses, including movement intermittency and harmonicity, number and type of submovements (movement primitives) fit per movement cycle, and the effects of vision on intermittency were used to support the model we propose, whereby there exist two subtypes of rhythmic movement; small-amplitude, high-frequency movements are nearly maximally harmonic, and harness the elastic properties of the limb to achieve smoothness and accuracy, and large-amplitude, low-frequency movements share characteristics with a string of discrete movements, and make use of visual feedback to achieve smoothness and accuracy.
(cont.) Bradykinesia (slowness of movement) is one of the hallmarks of PD. We examined the effects of visual feedback on bradykinesia. PD patients off dopaminergic medication and healthy age-matched controls performed significantly faster movements when visual feedback was withdrawn. For the bradykinetic subjects, this increase in movement speed meant either a mitigation or an elimination of bradykinesia. Our results support a role of the basal ganglia in sensorimotor integration, and argue for the integration of nonvision exercises into patients' physical therapy regime.
by Shelly Levy-Tzedek.
Ph.D.

This thesis focuses on the non-motor symptoms (NMS) of Parkinson's disease (PD), with particular emphasis on impulsive-compulsive spectrum behaviours (ICBs). The relevance of NMS is investigated as presenting complaints amongst 21% of 433 patients with pathologically-proven PD. These patients had delayed diagnosis of PD, and often underwent unnecessary and potentially harmful interventions. Motor and NMS of LRRK2- associated PD are compared with idiopathic PD, and NMS of LRRK2-associated PD are more benign than in idiopathic PD. Increased Lewy body burden was shown to correlate with NMS in a subgroup of idiopathic PD patients at post-mortem. A metanalysis investigates pathological gambling and the dopamine dysregulation syndrome in PD, highlighting the importance of dopamine agonists in pathological gambling. A new ICB in PD, named "reckless generosity", occurring in association with dopamine agonist use is described. Dopamine agonists are also implicated in the development of ICBs in patients with pathologically-confirmed progressive supranuclear palsy. An increased prevalence of excessive hoarding as a NMS of PD is shown, particularly in patients with other ICBs. Hoarding is shown to relate more to impulsivity measures than obsessive-compulsive symptoms. The overlap between sleep disturbance, dreams, mood and ICBs in PD is demonstrated. Sleep disturbance is independent of dopaminergic medication use, and instead relates to anxiety, depression, and the presence of ICBs. Reward learning in PD patients with and without ICBs, and healthy controls is tested on a reaction time game, the Salience Attribution Test. PD patients with ICBs show increased impulsivity on temporal discounting tasks, but do not show increased aberrant salience to rewards. Positron emission tomography (PET) scanning is used to investigate the dopaminergic pathways involved in ICBs by comparing PD patients with ICBs to those without ICBs after a L-dopa challenge and visual reward-related cue exposure. The results differ from studies on PD patients with addictive dopamine dysregulation, or other non-PD drug addicted individuals. The role of deep brain stimulation surgery for PD, patients with ICBs is investigated in a case series of 21 operated PD patients exhibiting ICBs at some stage during the course of their disease. The mixed results suggest the need for careful selection of patients for this procedure.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Background: Parkinson’s disease (PD) presents asymmetric early motor symptoms, and those symptoms affect the processing and the integration of proprioceptive information. Due to that, the upper limb motor control is impaired even on single task (isolated manual task) and dual task (manual task and posture control). Because these sort of tasks are performed during activities of daily living, the role of asymmetry on those task must be clarified to elucidate the effects of disease on PD functionality and thus guide the therapists choose more effective interventions. Among strategies of intervention on PD motor impairments, two strategies that deserve special attention are the instruction of external focus of attention and mirror therapy (MT). Both interventions might be potentially effective to facilitate motor learning. Aims: to assess the role of PD asymmetry on upper limbs motor control and postural control in conditions of single versus dual task; and tasks with attentional focus with instructions versus external focus as well as to verify the effect of MT on upper limbs motor control more affected on postural control of PD patients. Methods: Twenty PD patients were submitted to assessments on: Upper Limb motor control (kinematic analysis) and postural control (kinetics analysis), in single and dual task conditions, with and without external focus of attention. Posteriorly, the subjects were distributed in two different groups: GI1 and GI2. The MT protocol consisted in a unilateral home therapy on less affected upper limb, performed 30 minutes a day, five days a week, during 6 consecutives weeks. To assist the subjects of GI1, they performed this protocol using a visual feedback (mirror therapy). Both groups were assessed before and after therapy protocol. Results: performance was not different between upper limbs and single and dual tasks, both in single and in dual task. After protocol period, both groups showed improvements on kinematic outcomes (manual dexterity, movement frequency of the hand, hesitation and task performance time improvements, independent of the sort of focus of attention that was used). Conclusion: Manual task is not affected by PD asymmetry on single and dual task. The external focus of attention was not effective to improve the task performance in PD patients, and it is not recommended to be performed during dynamic tasks. The therapy protocol with or without visual feedback promotes extended benefits on execution and planning of manual task of more affected upper limb independently of focus of attention, but it is not able to decrease the functional and motor impairments neither improve postural control. Therefore MT seems to be equally effective on manual tasks benefits, however more studies are necessary to confirm this efficacy.
Introdução: a doença de Parkinson (DP) tem o início assimétrico dos sintomas motores e afeta o processamento e a integração das informações proprioceptivas, comprometendo o controle motor dos membros superiores tanto em tarefa singular (tarefa manual isolada) quanto em tarefa dupla (tarefa manual e controle postural). Por estas tarefas serem frequentemente exigidas nas atividades de vida diária, esclarecimentos quanto ao papel da assimetria da doença nessas tarefas podem elucidar sobre os efeitos da doença na funcionalidade dos pacientes e nortear a decisão sobre estratégias de intervenção mais pertinentes. Dentre as estratégias de intervenção para esses comprometimentos encontram-se a instrução de foco de ação externo e a terapia do espelho (TE). Ambas as intervenções podem ser potencialmente eficazes na DP por facilitar a aprendizagem motora. Objetivos: avaliar o papel da assimetria da doença no controle dos membros superiores e do controle postural nas condições de tarefa singular versus dupla e de tarefa com instrução de foco de atenção livre versus foco externo, assim como verificar o efeito da TE no controle motor do membro superior afetado e no controle postural de pacientes com DP. Método: 20 pacientes foram avaliados quanto ao controle dos membros superiores (análise cinemática) e ao controle postural (análise cinética), nas condições de tarefa singular e dupla, foco de atenção livre e externo. Posteriormente, os pacientes foram distribuídos nos grupos GI1 e GI2 e realizaram a intervenção que consistiu de treino unilateral do membro superior menos afetado, com duração de 30 minutos diários, 5 dias consecutivos na semana, durante 6 semanas, em domicílio. Na intervenção somente o GI1 utilizou o feedback visual - TE. Os grupos foram avaliados pré- e pós-intervenção. Resultados: o desempenho não diferiu entre os membros superiores e entre as condições de tarefa singular e dupla. O foco de atenção externo reduziu o desempenho da tarefa manual, tanto na tarefa singular quanto na dupla. Após o período de intervenção, ambos os grupos melhoraram o desempenho nas variáveis cinemáticas – aumentaram a destreza manual e a frequência de movimento da mão, diminuíram a hesitação na realização do movimento e o tempo para realizar a tarefa, independente do foco de atenção empregado. Conclusão: a assimetria da doença não interfere no desempenho da tarefa manual nas condições de tarefa singular e dupla. O foco de atenção externo não foi eficaz em melhorar o desempenho da tarefa manual em pacientes com DP, não devendo ser utilizado em tarefas dinâmicas. A intervenção, com ou sem feedback visual, melhora a execução e o planejamento da tarefa manual do membro superior afetado independente do foco atencional empregado, mas não é capaz de reduzir o comprometimento funcional e motor, nem de melhorar o desempenho do controle postural. Portanto, a TE parece ser igualmente eficaz na melhora do desempenho da tarefa manual, porém, mais estudos são necessários para afirmar sua efetividade.
CNPq: 157894/2013-4

The reach-to-eat movement, in which a hand is advanced towards a food item, shapes to grasp the food item, and withdrawals to place the food item into the mouth for eating, is a behaviour that is performed daily. The movement is controlled by two sensory systems, vision to guide hand advance and grasping, and somatosensation to guide hand withdrawal and mouth placement. The purpose of the present thesis was to examine how the sensory control of reaching-to-eat develops in infancy and degenerates following neurodegenerative disorder. The tight coupling of vision to hand advance and somatosensation to hand withdrawal has a developmental profile from six months to one year of age. That is, six-month-old infants rely on vision to advance their hand, grasp the target, and withdrawal the target to the mouth. By twelve months of age, infants display the adult pattern of coupling vision to hand advance and grasping. The tight coupling of vision to hand advance degenerates with basal ganglia disease, such that subjects with Parkinson’s disease and Huntington’s disease show an overreliance on vision to guide hand advance for grasping and hand withdrawal for mouth placement. The results of the thesis demonstrate that efficient use of sensory control to guide motor behaviour is an important aspect of development that is disrupted by neurodegenerative disease.
xiv, 286 leaves : ill. ; 29 cm

This research study examined motor control and procedural learning abilities in the oral and manual motor systems of adults who stutter, using people with Parkinson's disease, and age-matched controls as comparison groups. Participants in this study were asked to track a moving target on a computer screen with their jaw and with their dominant hand. Specifically, we compared their tracking accuracy for predictable and unpredictable signals. Procedural learning (defined as increased accuracy over time) was assessed by examining changes in tracking accuracy within a single tracking trial and between consecutive tracking trials of the same predictable condition. There were two main findings in this study related to tracking accuracy and procedural learning in people who stutter (PWS) and age-matched controls (CPWS). First, our analyses revealed that there was no significant difference between PWS and CPWS in the accuracy of tracking of either predictable or unpredictable conditions for either the hand or the jaw, although a trend was observed in which PWS performed more poorly in both for decreased accuracy. Second, both PWS and CPWS showed evidence of procedural learning to the same extent. There were two main findings in this study related to tracking accuracy and procedural learning in people who have Parkinson's disease (PPD) and age-matched controls (CPPD). First, tracking accuracy analyses revealed that PPD performed significantly more poorly than CPPD during jaw tracking of predictable conditions, but they were not significantly different from CPPD in jaw tracking of unpredictable conditions. During hand tracking PPD differed significantly from CPPD in tracking of both predictable and unpredictable conditions for their less accurate performance. Second, there was no significant difference between the two groups in the extent of procedural learning during jaw tracking. However, during hand tracking the PPD group improved less with time than the CPPD, suggesting that the PPD group had reduced procedural learning ability in the manual motor domain. Lastly, age was found to be an important factor determining tracking accuracy in our participants. Younger participants (PWS and CPWS) in the age range of 18-40 years had significantly better accuracy of jaw and hand tracking than the older individuals (PPD and CPPD) in the age range of 57-79 years.

Imaging studies have shown that response inhibition and conflict resolution, key executive functions essential for adaptive behaviour, are mediated by fronto-striatal circuits, specifically the right inferior frontal gyrus (IFG), pre-supplementary motor area (pre-SMA), and the subthalamic nucleus (STN). Overactivity of the STN and underactivation of the pre-SMA are features of Parkinson's disease (PD). The aim of this thesis was to investigate the hypothesis that the STN is involved in inhibition of action and serves to provide time for reflection and to slow down decision-making under conflict (Frank et al. 2006; 2007). The conditional stop signal reaction time was used. In Study 1, compared to controls, medicated PD patients showed impaired motor inhibition with prolonged stop signal reaction times (SSRTs), problems with conflict resolution, and impairment on tests of cognitive inhibition. In Study 2, PD patients were impaired on motor inhibition and conflict resolution compared to controls both on and off medication. Most importantly, medication status did not influence motor inhibition or conflict resolution in PD. In Study 3, bilateral deep brain stimulation of the STN impaired inhibition as indicated by significantly prolonged SSRTs, but had no significant effect on conflict resolution. However, Study 4, showed that compared to controls and unoperated PD, PD with unilateral subthalamotomies showed faster Go RTs and less conflict-induced slowing but at the expense of greater response selection errors. Finally, Study 5 investigated the contributions of the pre-SMA and IFG to motor inhibition and conflict resolution in healthy controls using transcranial magnetic stimulation. The results confirmed that the contribution of the right pre-SMA to response inhibition is essential. The results are consistent with the proposal that the STN and pre-SMA are involved in reactive inhibition and that the STN together with the pre-SMA influences the response threshold and speed-accuracy trade-offs.

La maladie de Parkinson est une maladie neurodégénérative secondaire à la mort des neurones dopaminergiques, entraînant un dysfonctionnement des ganglions de la base (GB), ensemble de noyaux sous corticaux impliqués dans le contrôle de la motricité. Les symptômes moteurs sont améliorés par le traitement dopaminergique et par la stimulation cérébrale profonde (SCP) du noyau subthalamique (NST). Il a été montré que le changement d’activité bêta est corrélé avec l’amélioration motrice des symptômes de bradykinésie et rigidité. L’hypothèse serait que les oscillations bêta pourraient être un physiomarqueur spécifique des symptômes moteurs de la MP. L’objectif de cette thèse est de comprendre l’activité du NST et de trouver un physiomarqueur de la MP : au repos et pendant un paradigme Go/Nogo.Dans une première partie, pour 55 patients, nous avons modélisé la puissance avec un modèle linéaire à effets mixtes dans six bandes de fréquences selon la position des électrodes, la présence de complications liées au traitement dopaminergique, de la sévérité des symptômes, et du changement de ces symptômes suite à la prise du traitement dopaminergique. Le changement le plus important entre OFF- et ON-DOPA est observé dans la bande low-bêta. Cependant, nous n’avons pas trouvé de corrélation entre la sévérité de la bradykinésie, rigidité, ou du score axial avec l’activité low-bêta. Mais, nous avons trouvé que la sévérité de la rigidité était associée aux fréquences supérieures à 20Hz. Nous avons également trouvé une corrélation positive entre la sévérité du tremblement dans toutes les bandes de fréquences, qui est très importante pour la bande thêta. Etonnement, nous avons trouvé que les complications liées au traitement dopaminergique pouvaient induire des informations dans toutes les bandes. Cet effet est très important pour la bande thêta. Nos résultats au repos suggèrent que l’activité bêta n’est pas le physiomarqueur idéal de la MP.Pendant le paradigme Go/Nogo, pour 15 patients, nous avons modélisé la puissance avec un modèle linéaire à effets mixtes pour toutes les fréquences selon la position des électrodes, la sévérité des symptômes, les données comportementales et cinétiques. Nous avons trouvé une spécificité temporelle et spatiale des activités du NST au cours du paradigme. Nos résultats montrent que le NST est impliqué dans le contrôle des différentes étapes du mouvement volontaire du membre supérieur et que le défaut de dopamine dans le circuit sensorimoteur des GB génère une série de changements oscillatoires au sein du NST lors du mouvement. Cependant, l'activité thêta est apparue comme une activité caractéristique en OFF-DOPA fortement corrélée aux paramètres comportementaux et cinétiques. Cette activité pourrait être le physiomarqueur de la MP pendant l'exécution d'un mouvement, son augmentation pourrait induire une réponse motrice et un mouvement rapide
The Parkinson's disease is a secondary neurodegenerative disease in the death of the dopaminergic neurons, pulling a dysfunction of the ganglions of the base (GB), the set pits under cortical implied in the control of the motricity

Electrical drive systems are used in various applications and getting more attractive in recent years. When the usage of electric motors increased in different applications then the control model of them has been also demanded. This work is aimed at deeper research to gain a better understanding of three different control models for electric motors, in case of this work a brushless direct current (BLDC) motor. Three different types of control models (6-step, sinusoidal and FOC control) have been investigated and designed using MATLAB/SIMULINK. Then the control models have been implemented in an Arduino Due based BLDC motor and its functionality has been configured. The results show that the FOC control model provided to work better in the simulation while the implementation of the hardware showed that sinusoidal control works a little better and smoother. Making the implementation of the control models to the hardware work better requires more works and this has been left for future work.

The shoulder is an inherently unstable joint and requires well-coordinated muscle work and an appropriate sensorimotor system for it to remain stable. The sensorimotor system is defined as all the sensory, motor, central integration and processing components involved in maintaining joint stability. Shoulder action involving overhead work places great demands on the shoulder joint and can result in shoulder lesions, such as impingement syndrome. Moreover, activities requiring repetitive arm movements, including high velocity actions, have also been identified as a risk factor for shoulder impingement.

The primary motor cortex (M1) is a key brain area for the generation and control of motor behaviour. Output from M1 can be driven in part by long-range inputs from a collection of thalamic nuclei termed the motor thalamus (MTh), but how MTh input shapes activity in M1 and forelimb motor behaviour remains largely unresolved. To address this issue, we first defined the 3D anatomical coordinates of mouse forelimb motor thalamus (MThFL) by employing conventional retrograde and virus-based tracing methods targeted to the forelimb region of M1 (M1FL). These complimentary approaches defined MThFL as a ~0.8 mm wide cluster of neurons with anatomical coordinates 1.1 mm caudal, 0.9 mm lateral to bregma and 3.2 mm below the pial surface. Thus, MThFL incorporates defined areas of the ventrolateral, ventral anterior and anteromedial thalamic nuclei. To investigate the importance of M1FL and MThFL during skilled motor behaviour, we developed and optimised a quantitative behavioural paradigm in which head-restrained mice execute forelimb lever pushes in response to an auditory cue to receive a water reward. Forelimb movement trajectories were mapped using high-speed digital imaging and multi-point kinematic analysis. We inactivated both M1FL and MThFL of mice performing this motor behaviour using a pharmacological strategy, which in both cases resulted in a significant reduction in task performance. Inactivating M1FL significantly affected forelimb coordination and dexterity, resulting in erratic motion and posture. In contrast, mice with MThFL inactivated displayed a reduction in total motor output, although correct posture was maintained. We performed extracellular recordings in MThFL of expert-level mice, demonstrating that motor thalamic output during execution of task was dominated by a robust response to the onset of the auditory cue. Cue-evoked responses were also observed in motor thalamic neurons of naive mice. We have developed a novel solution to the stability problem encountered when performing whole-cell patch-clamp recordings from the motor cortex of head-restrained mice performing forelimb motor behaviour, and present preliminary recordings maintained through the execution of forelimb behaviour.

This study investigates an adaptive control scheme designed to maintain accurate motor speed control in spite of high-frequency periodic variations in load torque, load inertia, and motor parameters. The controller adapts, stores and replays a schedule of torques to be delivered at discrete points throughout the periodic load cycle. The controller also adapts to non-periodic changes in load conditions which occur over several load cycles and contains inherent integrator control action to drive speed error to zero. Using computer simulations, the control method was successfully applied to a 3Φ synchronous motor and a permanent magnet D.C. motor. The D.C. motor (or A.C. servo-motor) controller has superior characteristics and this system performance was compared to P, PI and PID control for two severe load cases - a periodic step load and a four-bar linkage load. Simulation studies showed the schedule control method to be stable and in comparison to the PID controller to have 1) nearly the same speed of response but without the overshoot found in PID control, 2) nearly the same mean speed error (~ O), 3) 12-50 times better reduction in speed fluctuation, and 4) the schedule controller gains were much easier to find than PID gains for this low-order, highly responsive system.
Master of Science

Background The main objective of this thesis was to establish new insight into the motor control of low-threshold motor units in the trapezius muscle. Special attention was given to motor unit recruitment threshold related to firing behavior. The extensive literature on motor control mainly concerns firing behavior of extremity muscles. Motor control of the upper trapezius shows features that indicate deviations from the control scheme generally assumed to apply to muscles of the extremities. Knowledge of motor control of the trapezius is important in a pain development perspective, since shoulder/neck complaints are frequently localized to this muscle.

Methods Constant amplitude contractions of 2 to 30 min duration, with amplitudes between ~2–7% of maximal voluntary contraction (2-7% EMGmax), were used to study time-dependent changes in motor unit firing. Transient force increases reaching 15-20% EMGmax were superimposed on some of these contractions in an attempt to induce motor unit substitution. Sinusoidal contraction profiles were used to study firings in response to dynamic contractions. Motor unit firing was studied in 10 min contractions with vocational (typing) tasks and mental stress. The spike-triggered averaged (STA) technique was used to examine motor unit potentials and their dependence on contraction amplitude and firing history. The individual motor unit firings were recorded by intramuscular fine wire electrodes, while simultaneously recording the surface electromyographic (SEMG) signal. The Precision Decomposition technique was used to identify individual motor units with near 100% accuracy.

Results The results show that some low-threshold motor units stopped firing at the end of the EMG-pulses while motor units with initially higher threshold were recruited or stayed active. The lowest threshold motor units showed only brief silent periods. The mean firing rate increased from 10.5 to 12.5 pulses per second (pps) in response to contraction amplitudes of <2% and >4% EMGmax, but the mean firing rate the same for all motor units regardless of task and recruitment threshold given the SEMG amplitude. There was a strong rate modulation in dynamic contractions. STA-derived motor unit potentials indicated that motor units recruited below EMGmax had similar area at the same contraction amplitude. However, the area increased four-fold when SEMG amplitude increased from 1.5 to 10% EMGmax. Motor unit synchronization showed an average of 2.8% additional firings within of the triggering motor unit, estimated by peristimulus time histograms (PSTHs). A surprising finding was respiratory modulation of the firing rate at low contraction amplitudes. This modulation was attenuated by induced mental stress.

Conclusions Transient force increases promote derecruitment of motor units and may be attributed to inactivation of non-inactivating inward currents (plateau potentials). Silencing of motor units can be considered a protective mechanism to reduce the metabolic load on low-threshold motor units. The similar firing rates in sustained contractions independent of task and recruitment threshold suggest that the duration and pattern of silent periods are the most important variables to investigate in relation to motor unit over-exertion and subsequent pain development. The strong rate modulation in response to dynamic contractions indicates a control strategy resembling that of extremity muscles. STA-derived motor unit potentials indicate that units recruited below 10% EMGmax are of similar size, thus suggesting a deviation from the Henneman size principle. This may be an adaptation to postural functionality. The increase in STAderived potentials is largely due to motor unit synchronization. This points out limitations for this method when quantifying motor unit size, numbers and conduction velocity. Finally, respiratory modulation of firing rate and the attenuation by mental stress suggest at least two different sources of autonomic input that may facilitate motor unit activity.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 265-268).
This thesis presents the design, implementation and control of a new class of self-bearing motors. The primary thesis contributions include the design and experimental demonstration of hysteresis self-bearing motors, novel segmented stator structures, MIMO loop shaping control algorithm for levitation and commutation, hysteresis motor analysis including frequency dependency, nonlinear hysteresis model including loop widening, and a novel single-axis self-bearing motor, as well as a zero power configuration for this type of motor. In the late 1980s, the basic concepts of self-bearing motors was proposed. Since then, different types of AC and DC electric machines have been studied as a self-bearing motor. The self-bearing system is a key technology for high efficiency and compact systems with integrated magnetic levitation for high speed and high precision applications. One of the major disadvantages of existing self-bearing motors for high speed application is their rotor mechanical construction. Either the permanent magnet or induction machines rotor has mechanical features that introduces stress concentrations. Permanent magnets have very low mechanical strength and need to be inserted into the rotor. The assembly of magnets makes rotor vulnerable to mechanical failure at high speed. On the other hand, induction motors use soft steel to reduce hysteresis loss. Their rotors are slotted to either carry wires or in case of squirrel cages, having aluminum or copper bars. As a promising alternative, this thesis demonstrates hysteresis self-bearing motors which have a simple construction with a solid and smooth rotor. This is a very important characteristic for some applications. This type of system can also be used as a magnetic bearing that can apply a finite amount of torque. The rotor doesn't have to be laminated and can be made from high strength steel. We designed, built and tested this type of self-bearing motor successfully. In this thesis we also introduced a new type of segmented stator for hysteresis machines. The major advantages of this stator are: easy and low cost manufacturing, higher filling factor and higher motor efficiency. We tested the self-bearing concept successfully with this new configuration. We have also introduced a novel single axis self-bearing motor that is very suitable for rotors with large length to diameter aspect ratio, such as high speed flywheels for energy storage. We implemented a zero power levitation condition along with passive damping for this system that has several advantages for high speed systems. One of the major advantages of zero power systems is the simple and robust touch down bearing design which is a key element for active magnetic bearings and self-bearing motors. This is mainly because the bearings experience minimal load in case of power failure. Hysteresis is a time-rate dependent phenomena which is fundamentally related to eddy current formation in the material and the thermal agitation. Hysteresis loops of materials with large hysteresis are highly frequency dependent. Therefore we added hysteresis frequency dependency to hysteresis motor analysis, which is believed to be a novel contribution . We have also developed linear and nonlinear analyses for the stabilizing forces and moments for hysteresis self-bearing motor. The nonlinear analysis is based on Chua's nonlinear hysteresis model that includes loop widening. The theoretical results were verified by experimental data for three different type motor configurations with good accuracy. Finally, we built two identical induction machines except for the rotor material. One rotor is a commercial squirrel cage and the other one is a simple solid rotor made out of hysteresis material(D2 steel). We ran the IEEE standard tests for these motors and compared their performance under different circumstances.
by Mohammad Imani Nejad.
Ph.D.

The purpose of this thesis was to explore the behavior in power sharing and control of Hybrid Motor Drives. In this research, a solar-based hybrid adjustable-speed pump, which has been developed in the laboratory, was used to investigate the power-sharing in hybrid (dual-input) motor-drive systems. The laboratory test setup contained a DC-DC module connected to the DC-bus capacitors of a 2.5hp 230V PWM-based adjustable-speed motor-drive. The experimental results demonstrate that the power-sharing of a Photovoltaic (PV) array/DC-DC converter is not a function of motor speed in hybrid solar-based motor-drives, as long as the power contribution of the AC-grid stays above zero. In these conditions, the PV-DC-DC module behaves like a current source, and the dynamic behavior of the motor is decoupled from the dynamic behavior of the AC-grid, given that the PV-DC-DC module can provide the motor load.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
Includes bibliographical references (p. 207-215).
Motor learning for humans is based on the capacity of the central nervous system (CNS) to perform computation and build an internal model for a task. This thesis investigates the CNS's ability to generalize a learned motor skill throughout neighboring spatial locations, its ability to divide the spatial general­ization with variation of context, and proposes models of how these generalizations might be implemented. The investigation involved human psychophysics and simulations. The experi­mental paradigm was to study human neuromuscular adaptation to viscous force perturbation. When external perturbations were applied to the hand during a reach­ing task, the movement became distorted. This distortion motivated the CNS to produce counterbalancing forces, which resulted in the modification of the internal model for the task. Experimental results indicated that the introduction of interfering perturbations near the trained location disturbed the learned skill. In addition, if the same move­ment was perturbed in two opposite directions in sequence, neither of the forces are learned. Conversely, the adaptation to two opposite forces was possible within the same space when the forces were applied to two contextually distinguished movements. This was possible only when these movements were interleaved fairly regularly. During the adaptation to a difficult task, such as contextual distinction in the same spatial location, humans often used other strategies to avoid learning the actual paradigm. These strategies allowed subjects to perform the task -- without changing their internal models appropriately, and thus this was also investigated as a part of the learning process. Finally, a multiple function model was constructed which allowed multiple contex­tually dependent functions to co-exist within one state space. The sensory feedback affected all functions, however, only one function was active to output a motor com­mand. This model supported the experimental data presented. The results of the psychophysical experiments as well as an explanation of the simulations and models that were developed will be presented in this thesis.
by Yoky Matsuoka.
Ph.D.

This project is about making an embedded system in order to control different functionalities of a stepper motor. The main functions of this stepper motor are to control the speed and direction. The whole hardware consists of two parts. One is the transmitter side and the other side is the receiver side. The transmitter side consists of PC, Encoder, a microcontroller and RF (Radio Frequency) transmitter. On the receiver side there is an RF receiver, a decoder, a microcontroller, a motor driver and a stepper motor. During this project a wireless system is going to be used to enhance the stepper motor operated manually. This system will actually adapt the requirements of the modern technology. With the help of this system one can control the speed of the stepper motor controller from remote sites. It can also control the direction of the stepper motor. In order to make it user friendly we make a GUI for controlling it from the PC. The data is sent and received via transmitter and receiver respectively. This data will be encoded and decoded and sent to the motor driver from where it is sent to the stepper motor in order to perform the operations.
0734-954624

1.1 Objectius de la tesi.
En els últims anys el control del parell i de la velocitat del motor d'inducció ha estat llargament estudiat. Un cop s'ha considerat que les prestacions dinàmiques assolibles eren ja suficientment satisfactòries, els diferents investigadors han reorientat els seus esforços cap a altres enfocs relacionats, ja no únicament amb el MI estrictament parlant, sinó amb tot el sistema que constitueix l'accionament amb si mateix.

L'objectiu principal d'aquesta tesi és posar en evidència, l'existència d'unes idealitzacions i limitacions dels controls tradicionals de parell i velocitat del motor d'inducció (bàsicament del Control Vectorial i del DTC), així com a proposar mètodes i algorismes alternatius que superin a les mateixes.

1.2 Estructura i contingut

El Capítol 1 conté una introducció al treball.

El segon capítol Modelització del motor d'inducció, presenta les principals tècniques i equacions, que porten a descriure d'una forma dinàmica al MI.

El tercer capítol, Control de parell i velocitat del MI, es descriuen els Control Vectorial i el Control Directe de Parell (DTC), ja que són els més estudiats en la literatura.

El quart capítol, Estudi dels bucles de corrent, tracta més en profunditat una de les limitacions que presenta el Control Vectorial, l'estudi de les interaccions que hi ha entre els dos llaços de regulació de les intensitats de l'estator (la seva component directa i en quadratura).

En el cinquè capítol, OSVPWM (Optimized Space Vector PWM), es presenta un estudi detallat dels diferents mètodes d'ondulació (DC/AC) que existeixen. D'entre tots aquests, s'estudia amb molt més deteniment el Space Vector PWM (SVPWM), aportant un nou algorisme d'implementació del mateix (optimitzat per DSP's), així com posant en evidència la negativa influència dels temps morts sobre el mateix.

El sisè capítol presenta l'ODTC (Optimized Direct Torque Control), com a resum de tots els capítols anteriors.
1.3 Aportacions d'aquesta tesi.

En la modelització matemàtica del Motor d'Inducció, s'ha arribat a la formulació d'una equació genèrica, que engloba totes les possibles referències, i totes les definicions d'intensitats magnetitzants.

En l'estudi del DTC s'ha presentat una nova taula de commutació, que permet disminuir l'excessiu arrissat de parell que presenta la taula de commutació tradicional.

En l'estudi del SVPWM s'ha presentat una nova formulació molt més apta per a la seva implementació en DSP (Digital Signal Processor). Igualment, s'ha posat en evidència la important influència dels temps morts dels interruptors, en la THD (Tasa de Distorsió Harmònica) de l'ona de tensió de sortida de l'ondulador proposant un algorisme de compensació (OSVPWM).

S'ha proposat un nou algorisme de control del parell del MI, incorporant les prestacions del DTC en règim transitori (ràpida resposta del parell), i les prestacions del Control Vectorial en règim permanent (petit arrissat de parell), amb la incorporació de l'OSVPWM com a estratègia de modulació.

Finalment destacar, l'aportació d'un equip experimental basat en DSP, de disseny molt versàtil i robust, i que incorpora tota una sèrie d'eines de desenvolupament que el fan molt útil per a l'experimentació de noves lleis de control, referides principalment al motor d'inducció, però que també s'ha demostrat eficient alhora de treballar amb altres plantes com és el cas dels SAI's (Sistemes d'Alimentació Ininterrompuda).

1.4 Futures línies de recerca.

Seguir treballant en l'estudi del OSVPM, però en el cas de la sobremodulació, és a dir, quan la tensió de consigna superi o surti fora dels rangs d'aplicabilitat del mateix.

Amb l'obtenció de l'equació que ens permet estimar l'arrissat màxim de parell, associat al conjunt motor-ondulador, estudiar el disseny de controladors per histèresi de banda d'histèresi variable (funció de l'estat de l'accionament).

Finalment destacar, que amb el constant augment de la potència de càlcul dels DSP, les possibilitats de noves lleis de control del MI ("fuzzy logic" i "passivity control") són cada dia més possibles, i per tant s'han convertit en una línia de treball molt interessant.

The main aim of this project was to research, develop and test an induction motor drive not requiring a speed encoder, but which could be considered commercially viable by motor drives manufacturers, and which should aim to meet the follow requirements: • Dynamic torque performance and steady state speed-holding accuracy to be comparable with encodered vector controlled drives • Extensive and highly accurate knowledge of electrical and mechanical parameters of the motor and load not to be required • Extensive commissioning from an expert engineer not to be necessary • Algorithm not to rely on excessive computational capability being available The drive was to operate, in a stable manner, over speed and load ranges at least comparable with commercially available sensorless induction motor drives. The above requirements were set such that the developed sensorless technique may be considered for synchronised multi-motor process applications, where the advantages of a sensorless system could be exploited for hazardous, damp and hot conditions. The solution developed consists of a leading model-based sensorless method augmented with a speed estimator that tracks harmonics, seen in the stator terminal quantities, due to rotor slotting. The model-based scheme facilitates field-orientated control for dynamic performance. The slot harmonic speed estimator tunes the model for speed accuracy. Slot harmonics are identified using a recursive signal processing method termed the Recursive Maximum Likelihood - Adaptive Tracking Filter. This work is the first example of the method being developed into a practical sensorless drive system and the complete speed identifier is described, including set-up, pre-filtering and the minimal parameter considerations. Being recursive the method is computationally efficient, yet has accuracy comparable with that of FFT identifiers used in other work. The developed sensorless strategy was implemented practically on two motor drive systems. The performance of the scheme is shown to give encoder like speed holding accuracy and field-orientated dynamic performance. The two drives were also configured and tested as a speed synchronised pair, using applicable multi-motor control techniques, themselves compared and contrasted. The sensorless performance is demonstrated, alongside an encodered version acting as a benchmark, and the performance of the two schemes is shown to be highly comparable. The author has found no other example of sensorless techniques considered for use in multi-motor applications. The use of such a technique brings established advantages associated with encoder removal and allows multi-axis electronic synchronisation to be considered for parts of a process where an encoder may not be appropriate.

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Objetivo: Avaliar o efeito do exerc?cio de dupla-tarefa em meio aqu?tico sobre a fun??o motora de pacientes com doen?a de Parkinson avan?ada (2-3 H&Y). M?todo: Em um ensaio cl?nico controlado, 12 pacientes da Neurocl?nica do Hospital Universit?rio Onofre Lopes - UFRN foram distribu?dos nos grupos exerc?cio (GE; n=7) e controle (GC; n=5). Os participantes do GE foram expostos ? 12 sess?es com 30 min de caminhada em ?gua funda com dupla-tarefa, durante 4 semanas. O GC permaneceu em rotina sedent?ria. A fun??o motora foi avaliada a partir da Escala Unificada da DP ? Motor (UPDRS-III), e dos testes de for?a de membros superiores e inferiores, e de agilidade da bateria Senior Fitness Test (SFT), antes e ap?s a interven??o. A normalidade e a homogeneidade das vari?ncias foram verificadas atrav?s dos testes de Shapiro-Wilk e de Levene, respectivamente. Os dados de capacidade f?sica foram normalizados por transforma??o logar?tmica. As vari?veis param?tricas e n?o param?tricas foram comparadas atrav?s do Teste t independente, e do Teste U de Mann-Whitney, tamb?m utilizados para a caracteriza??o da amostra. ANOVA mista de medidas repetidas, com post hoc de Bonferroni para compara??es entre e intra-grupos das vari?veis dependentes. O tamanho do efeito foi calculado pelo eta quadrado parcial (?2p) e pelo d de Cohen. Foi utilizado n?vel de signific?ncia de p<0,05. Resultados: Houve diferen?a significativa pr? p?s-interven??o na fun??o motora geral, com um efeito moderado sobre GE em rela??o ao GC (p>0,001; d=0,44). Uma melhora significativa tamb?m foi observada na agilidade e equil?brio din?mico (p=0,001), assim como na estabilidade postural (p=0,04) no parametro individual de bradicinesia (p=0,001) dos pacientes expostos ao exerc?cio. Conclus?o: O exerc?cio promoveu efeito positivo no desempenho de capacidades neuromotoras envolvidas nos processos degenerativos da DP, importante para a melhor execu??o de tarefas funcionais como a marcha, precocemente comprometida pela doen?a.
Aim: to evaluate the effect of 4 weeks of aquatic walking with dual-motor task on motor function of severe Parkinson Disease patients. Method: Twelve PD patients were divided into exercise (EG=7) and control (CG=5) groups. The EG completed 12 sessions of 30 min walking into deep water while executing dual-task, at moderate intensity, during 4 weeks with motor function (Unified Parkinson Disease?s Rate Scale III and Senior Fitness Test) measures taken before and after this period. Normality and homogeneity of variances were checked by Shapiro-Wilk and Lavene?s test respectively. Data of parametric variable are presented in mean and SD as well as in median and interquartile range for non-parametric variable. Data from the SFT was normalized by logarithmic transformation. Independent t test was used to compare parametric variables of the sample characterization, and Mann-Whitney U test, for non-parametric. ANOVA Split-splot (2x2) with Bonferroni?s post hoc was applied for comparison inter and intra-groups of all dependent variable. Size effect was calculated by Eta squared (? 2 p ) and Cohen?s d, with a significance of p<0,05. Results: PD patients yielded significant improvement of motor function pre-post exercise, with a moderate effect (p>0,001; d=0,44). Bradykinesia (p=0,001), agility (p=0,001) and postural balance (p=0,04) also expressed significant changes individually. Conclusion: Regular aerobic exercise with cognitive-motor interference stimuli may counteract the motor symptoms of PD neurodegeneration.

In this thesis, position and current control systems for a brushless DC (Direct Current) motor are designed and integrated into one FPGA (Field Programmable Gate Array) chip. Experimental results are obtained by driving the brushless DC motors of Control Actuation System of a guided missile. Because of their high performance, brushless DC motors are widely used in Control Actuation Systems of guided missiles. In order to control the motor torque, current controller is designed and implemented in the FPGA. Position controller is designed to fulfill the position commands. A soft processor in the FPGA is used to connect and configure the current controller, position sensor interfaces and communication modules such as UART (Universal Asynchronous Receiver Transmitter) and Spacewire. In addition
position controller is implemented in the soft processor in the FPGA. An FPGA based electronic board is designed and manufactured to implement control algorithms, power converter circuitry and to perform other tasks such as communication with PC (Personal Computer). In order to monitor the behavior of the controllers in real time and to achieve performance tests, a graphical user interface is provided.

This report is the result of a master thesis work where the goal was to develop acontrol system for a type of ultrasonic motor. The ultrasonic motors use ultrasonicvibrations from a piezoelectric material to produce a rotating motion. They arepowered by two sinusoidal voltages and their control signals generally are thevoltages amplitude, frequency and the phase difference between the two voltages.In this work the focus is on control using only amplitude and frequency. A feedbacksignal was provided by an encoder, giving an angular position. The behavior of themotors were investigated for various sets of control signals. From collected data alinearized static model was derived for the motor speed. This derived model wasused to create a two part control system, with an inner control loop to managethe speed of the motors using a PI controller and an outer control loop to managethe position of the motors. A simple algorithm was used for the position controland the result was a control system able to position the motors with a 0.1 degreeaccuracy. The motors show potential for greater accuracy with a position feedback,but the result in this work is limited by the encoder used in the experiments.

Saab has an analogue solution which is used to drive small motors in aircrafts. The motor is a brushless DC-motor and uses a resolver and hall sensors to control it. As sensorless control is something that has been expanding and attracting more interest over the last decade, Saab is considering the possibility of using a digital sensorless system depending on its performance on the control compared to their analogue system. There is little documentation of performance for a digital sensorless solution compared to an analogue solution. Therefore the question to be answered in this research is: How is the performance of the digital solution compared to the existing analogue solution? It was answered by finding a complete sensorless system on the market and then compare its performance to a digital system with sensors that resembles the analogue solution. Performance wise, InstaSPIN does not perform as well as EPOS2 which represent the sensorless system respective the system with sensors. InstaSPIN needs a startup sequence, can not run at the same low velocities, has a longer rise time, settling time and greater ripple. An examination of the software should be done before using the disadvantages that was found as a reason for not considering a sensorless system. Especially the startup sequence in the software should be examined as it is InstaSPINs greatest weakness compared to EPOS2.
Saab använder idag ett analogt system för att driva små motorer i deras flygfarkoster. Det analoga systemet använder en borstlös DC-motor och en resolver för styrning av motorn. Motorstyrning med system som är oberoende av givare är ett område som vuxit och fått ett ökat intresse det senaste decenniet. Saab överväger möjligheten att använda ett givarlöst digitalt system beroende på dess styrprestanda jämfört med deras analoga system. Eftersom det finns lite dokumentation om prestandan så är frågan som ska besvaras i denna rapport: Hur förhåller sig det givarlösa digitala systemet prestandamässigt jämfört med det existerande analoga systemet? Detta besvarades genom att leta upp ett komplett system på marknaden och sedan jämföra dess prestanda mot ett digitalt system som liknar det analoga systemet.  Prestandamässigt så fungerar InstaSPIN som representerar det givarlösa systemet inte lika effektivt som EPOS2 som representerar systemet som använder givare. Nackdelarna med InstaSPIN är att den behöver en startsekvens, inte kan köra på lika låga hastigheter, har längre stigtid, insvängningstid och större rippel. Man bör undersöka mjukvaran innan nackdelarna används som en anledning till att inte använda ett givarlöst system. Speciellt startsekvensen bör undersökas eftersom det är IntaSPINs största svaghet jämfört mot EPOS2.

The goal of the research described in this thesis is to further our understanding of the motor control strategies that are available to the child when learning to produce meaningful interactions with environmental surfaces. The principal aim is to explore the analytical techniques that could be used to evaluate the range of neuromechanical responses for the lower limb that would provide stability at the limb/environment interface during growth and development. Five studies are presented that provide both experimental data and theoretical perspectives that were coalesced in the formulation of a general model for the control of stability at the limb/environment interface. The first study presents an analytical technique that was devised to classify the spatial-temporal organization of the surface myoelectric activity into one of three distinct patterns: Burst, Tonic, and Tonic Burst. This classification permits the matching between the pattern of muscle activity and the kinematic and kinetic control of the ground contact phase of landing. In the second, and companion paper, different distributions of the Burst, Tonic, and Tonic Burst patterns across the muscles of the lower limb were associated with three mechanical responses of the limb to ground contact. Mechanically, the three limb responses show a progression toward an effective control of stability at the limb/environment interface and it was therefore proposed that the distribution of activity patterns could reflect the priorities of system at different stages of growth and development. The results support our hypothesis that more complex movements can be executed when the limits of stability are maximized. Study three presents a formal model for the control of stability at the limb/environment interface. The model was further applied to propose new theoretical approaches that could be used in the clinical milieu, shifting the focus of the evaluation to the range of feasible movements that would be available

This report will review critically the available research on deep brain stimulation and levodopa as a means of treatment for Parkinson’s disease in an attempt to determine why neither of these treatments improves speech.
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初級運動皮質直接負責運動控制。大量關於帕金森式癥(PD)的有效治療手段的研究已經證明，初級運動皮質在病理情況下的功能改變，直接與患者運動障礙相關。本論文的研究重點在於探索初級運動皮質在深部腦刺激治療帕金森氏症的運動障礙的過程中發揮的作用及其與運動學習功能障礙的聯繫。
丘腦底核深部腦刺激(STN-DBS) 已被廣泛應用於治療帕金森式症。雖然該項治療手段能顯著地改善患者的運動功能障礙，但其確切的治療機制仍未明確。理論上來說，丘腦底核深部腦刺激能夠直接啟動丘腦底核內部和其周圍很大範圍的神經組織，包括丘腦底核內部本身的神經元胞體，以及與其相連接的輸入輸出核團的神經元軸突。在丘腦底核眾多輸入核團之中，一個重要的神經輸入來自於初級運動皮質(MI)第五層的離皮質神經元(CxFn)，電刺激引起的逆行皮質啟動作用被提出，用於解釋丘腦底核深部腦刺激的治療機制。
為了研究逆行皮質啟動效應究竟如何在丘腦底核深部腦刺激的過程之中帶來治療效果，我們採用多通道神經電生理信號記錄系統在自由活動的單側帕金森大鼠的初級運動皮質進行鋒電位元和局部場電位元信號的記錄。實驗結果證明，當對丘腦底核進行高頻電刺激，在運動皮質第五層的離皮質神經元能成功記錄到保持固定延時的逆行鋒電位。由於增加刺激頻率會引起逆行鋒電位被成功記錄到的百分比下降，因此當深部腦刺激的頻率選擇在125Hz時，逆行鋒電位的放電頻率達到最高，而此刺激頻率正好與行為學實驗中帶來最佳治療效果的刺激頻率一致。於此同時，逆行皮質啟動作用還伴隨著初級運動皮質離皮質神經元的自發放電頻率增加、同步性爆發式放電減少等電生理信號特點。場電位分析的結果進一步表明，丘腦底核深部腦刺激減弱了病理情況下出現的beta波頻譜能量增高以及鋒電位-場電位相干性增強。更重要的是，我們發現只有逆行鋒電位被成功誘發，離皮質神經元的發放電機率才能被調節。這點有力地表明由電刺激隨機誘發的逆行鋒電位傳導至初級運動皮質，直接幹預並抑制了離皮質神經元在病理情況下的同步性爆發式放電活動，從而緩解了帕金森氏症的運動障礙。
另外，初級運動皮質並不僅僅是一個靜態的運動控制中樞，更為重要的功能在於它參與著與運動學習和運動記憶相關的動態資訊編碼。帕金森氏症患者普遍存在皮質可塑性減弱以及運動技能學習障礙。由於初級運動皮質分層結構的存在，層內神經元之間的突觸連接為神經可塑性提供了很好的結構基礎。因此，我們在初級運動皮質誘發在體長時程增強(LTP)，旨在研究與運動技能學習相關的皮質神經可塑性的動態變化過程，以及探索中腦多巴胺能投射系統對皮質神經可塑性的影響。
一方面，我們採用間斷性高頻刺激誘發在體長時程增強，證實六羥多巴損毀後皮質的長時程增強水準顯著下降。另一方面，我們設計前肢抓食的行為學範式用來評價動物在運動技能學習的不同階段皮質可塑性發生的動態變化。實驗結果表明，直接損毀皮質的多巴胺能輸入，模型組大鼠與假實驗組大鼠的行為表現在初期的技能獲取階段並無明顯差異，而只在後期的技能鞏固階段模型組大鼠表現出技能鞏固障礙。更為有趣的是，兩組行為學變化趨勢與各自的在體長時程增強的變化趨勢有很高的一致性。本研究表明多巴胺對初級運動皮質的支配在運動記憶的鞏固過程中起著關鍵作用。在帕金森氏症的病理情況下，多巴胺耗竭將影響皮質的突觸可塑性，從而造成帕金森患者在運動技能的鞏固階段表現出障礙。
The primary motor cortex (MI) controls movement directly, but is an under-investigated brain region in the pathogenesis and treatment of Parkinsonian motor disability, when compared with the basal ganglia circuitry. In this study, the roles of MI in underlying the therapeutic action of surgical deep brain stimulation and motor learning impairment were investigated.
Deep brain stimulation of the subthalamic nucleus (STN-DBS) is now a recognized therapeutic option for Parkinson’s disease (PD). Although this surgical strategy provides behavioral benefits remarkably, its exact mechanism is still a matter of controversy. In principle, STN-DBS can directly activate a wide range of neuronal elements within the STN and surrounding areas. As the corticofugal neurons (CxFn) in the layer V motor cortex provide a major input to the STN, we hypothesized that the stimulation evoked antidromic cortical activation is involved in the therapeutic mechanism of STN-DBS. In the first series of experiments, we performed simultaneous recordings of multi-unit neuronal activities and local field potentials (LFPs) in MI in freely moving hemi-parkinsonian rats. By identifying stimulation evoked antidromic spike, which occurred at a fixed, short latency, CxFn located in the layer V MI were identified. Increasing stimulation frequency also increased failure rate of activation, resulting in a peak frequency of stochastic antidromic spikes at 125Hz STN-DBS, which was correlated with the optimal therapeutic efficacy observed in behavioral tests. Meanwhile, this antidromic effect was accompanied by the rectification of pathological neuronal activities including increased spontaneous firing rate, reduced burst discharge and synchrony among the CxFn. Field potential analysis revealed that STN-DBS alleviated the dominance of pathological beta band oscillation and spike-field coherence in the MI. More importantly, it was found that the firing probability of CxFn could only be modified following the occurrence of antidromic spikes, suggesting that direct interference of stochastic antidromic spikes with pathological neuronal activities underlies the beneficial effect of STN-DBS.
The MI is not simply a static motor control structure. It also contains a dynamic substrate that participates in motor learning or stores motor memory. In PD patients, loss of cortical plasticity and impaired motor learning is a common feature. As the intrinsic horizontal neuronal connections in MI are a strong candidate of cellular correlate for activity-dependent plasticity, in the second series of experiments, we developed in vivo long-term potentiation (LTP) technique in the MI to investigate the dynamics of cortical plasticity during motor skill learning and the role of the innervation by mesocortical dopamine input. Local depletion of dopamine in the primary motor cortex resulted in reduced performance in the forelimb reaching for food learning task. Although the performance of the PD rats in the initial learning phase was comparable to that of the sham-operated group, as training continued, these animals exhibited deficit in consolidating the motor skill. These deficits closely paralleled the impairment in training-enhanced synaptic connections in layer V neurons, and the in vivo LTP of evoked field excitatory postsynaptic potentials induced by intermittent high frequency stimulation. In addition, progressive recruitment of task-specific neurons was suppressed. Our study therefore revealed that dopamine depletion confined to the MI could lead to impairment in cortical synaptic plasticity which may preferentially affect the consolidation, but not the acquisition, of motor skills. These findings shed light on the cellular mechanisms of motor skill learning and could explain the decreased ability of PD patients in learning new motor skills.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Li, Qian.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references (leaves 168-190).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts also in Chinese.
CHAPTER 1 --- p.1
General Introduction --- p.1
Chapter 1.1 --- Anatomical organization of the basal ganglia --- p.1
Chapter 1.1.1 --- Overview of the basal ganglia circuit --- p.1
Chapter 1.1.2 --- Cortico-basal ganglia-cortical circuit --- p.1
Chapter 1.1.2.1 --- Direct and indirect pathway --- p.2
Chapter 1.1.2.2 --- Hyperdirect pathway --- p.2
Chapter 1.1.2.3 --- The midbrain dopamine system --- p.2
Chapter 1.2 --- Striatum --- p.3
Chapter 1.2.1 --- Cell types in the striatum. --- p.3
Chapter 1.2.2 --- The Cortico-striatal system --- p.4
Chapter 1.3 --- Subthalamic Nucleus --- p.5
Chapter 1.3.1 --- Neuronal property of the STN. --- p.5
Chapter 1.3.2 --- Electrophysiological property of the STN --- p.6
Chapter 1.3.3 --- Cortico-subthalamic system --- p.7
Chapter 1.3.4 --- Functional significance of the cortico-subthalamic and corticostriatal system. --- p.8
Chapter 1.4 --- Parkinson’s disease --- p.9
Chapter 1.4.1 --- Pathogenesis of PD --- p.9
Chapter 1.4.2 --- Genetic risk factors of PD --- p.10
Chapter 1.4.3 --- Progressive motor symptoms of PD --- p.11
Chapter 1.4.4 --- Non-motor symptoms of PD --- p.13
Chapter 1.4.5 --- Pathological neuronal rhythms in the basal ganglia of PD. --- p.16
Chapter 1.5 --- Experimental studies of PD. --- p.18
Chapter 1.5.1 --- Animal modeling of PD. --- p.18
Chapter 1.5.2 --- Motor deficits evaluation in rodent models of PD --- p.21
Chapter 1.5.3 --- Non-motor symptoms evaluation in experimental models of PD --- p.24
Chapter 1.6 --- Deep Brain Stimulation --- p.27
Chapter 1.6.1 --- DBS in alleviating Parkinsonian motor symptoms --- p.28
Chapter 1.6.2 --- DBS in alleviating Parkinsonian non-motor symptoms --- p.29
Chapter 1.6.3 --- Investigation of the STN-DBS mechanism. --- p.31
Chapter 1.6.3.1 --- Local inhibitory effect within the STN --- p.32
Chapter 1.6.3.2 --- Excitatory effect at output nuclei --- p.33
Chapter 1.6.3.3 --- The de-coupling of soma and axons at system level --- p.34
Chapter 1.6.3.4 --- Effects of DBS on abnormal rate or pattern --- p.35
Chapter 1.6.3.5 --- Antidromic propagation of DBS effect towards cortex --- p.37
Chapter 1.7 --- Objective --- p.38
Chapter 1.8 --- Figures --- p.41
CHAPTER 2 --- p.47
General Methods --- p.47
Chapter 2.1 --- Animals --- p.47
Chapter 2.2 --- Stereotaxic surgery --- p.47
Chapter 2.2.1 --- Preoperative preparation --- p.47
Chapter 2.2.2 --- Anesthesia and craniotomy --- p.48
Chapter 2.2.3 --- Induction of hemi-Parkinsonian rat model --- p.48
Chapter 2.2.4 --- Electrode implantation techniques. --- p.49
Chapter 2.3 --- Behavioral assessment. --- p.50
Chapter 2.3.1 --- Apomorphine-induced contralateral rotation. --- p.50
Chapter 2.3.2 --- Open field test --- p.50
Chapter 2.4 --- STN-DBS protocol --- p.50
Chapter 2.5 --- Electrophysiological data acquisition --- p.51
Chapter 2.6 --- Data analysis --- p.52
Chapter 2.6.1 --- Statistical analysis of behavioral data --- p.52
Chapter 2.6.2 --- Electrophysiological data --- p.52
Chapter 2.6.2.1 --- Stimulation artifact removal --- p.52
Chapter 2.6.2.2 --- Multi-unit spike sorting --- p.53
Chapter 2.6.2.3 --- Electrophysiological identification of pyramidal neuron and interneuron. --- p.54
Chapter 2.6.2.4 --- Identification of antidromic cortical activation --- p.54
Chapter 2.6.2.5 --- Discharge pattern classification --- p.54
Chapter 2.6.2.6 --- Synchrony level evaluation --- p.55
Chapter 2.6.2.7 --- Oscillatory rhythm characterization --- p.55
Chapter 2.6.2.8 --- Coherence Level Measurement --- p.56
Chapter 2.7 --- Histological verification --- p.56
Chapter 2.8 --- Figures --- p.58
CHAPTER 3 --- p.60
Alleviation of Parkinsonian Motor Symptoms during Deep Brain Stimulation in Hemi-Parkinsonian Rats --- p.60
Chapter 3.1 --- Introduction --- p.60
Chapter 3.2 --- Materials & Methods --- p.61
Chapter 3.2.1 --- Animals --- p.61
Chapter 3.2.2 --- Chemicals --- p.61
Chapter 3.2.3 --- Equipment --- p.61
Chapter 3.3 --- Results --- p.62
Chapter 3.3.1 --- Time course of the Apomorphine induced rotation behavior --- p.62
Chapter 3.3.2 --- Dose-dependence of the Apomorphine induced rotation --- p.62
Chapter 3.3.3 --- Acute behavioral response to STN-DBS. --- p.63
Chapter 3.3.4 --- The dependence of STN-DBS effect on stimulation paradigm. --- p.64
Chapter 3.3.5 --- Acute effects of STN-DBS on APO induced rotation. --- p.64
Chapter 3.3.6 --- Long-term effects of STN-DBS on APO induced rotation --- p.64
Chapter 3.3.7 --- Histological confirmation of the stimulation electrodes localization --- p.65
Chapter 3.3.8 --- Loss of DA neurons in the SNc --- p.65
Chapter 3.3.9 --- Reductions of the DA axon terminals in the striatum --- p.65
Chapter 3.3.10 --- Chronic STN-DBS failed to rescue nigrostsriatal and striatal DA --- p.66
Chapter 3.4 --- Discussion --- p.66
Chapter 3.4.1 --- Neurotoxic mechanism of 6-OHDA --- p.66
Chapter 3.4.2 --- Time course of dopamine degeneration induced by 6-OHDA --- p.66
Chapter 3.4.3 --- Failure in observing worsened motor symptoms during low frequency STN-DBS. --- p.67
Chapter 3.4.4 --- Experimental DBS based on rat model: does it mimic human case? --- p.67
Chapter 3.4.5 --- Technical issues about STN-DBS --- p.69
Chapter 3.5 --- Figures --- p.72
CHAPTER 4 --- p.82
Direct involvement of the Corticofugal Neurons in Motor Cortex during Therapeutic Deep Brain Stimulation --- p.82
Chapter 4.1 --- Introduction --- p.82
Chapter 4.2 --- Materials --- p.83
Chapter 4.2.1 --- Animals --- p.83
Chapter 4.2.2 --- Chemicals --- p.83
Chapter 4.2.3 --- Equipment --- p.83
Chapter 4.3 --- Results --- p.84
Chapter 4.3.1 --- Identification of CxFn based on antidromic effect --- p.84
Chapter 4.3.2 --- Antidromic spikes frequency correlates with therapeutic effect of STN-DBS. --- p.84
Chapter 4.3.3 --- Pathological changes of neuronal firing rate in MI --- p.85
Chapter 4.3.4 --- Only high frequency STN-DBS normalizes neuronal firing rate in MI --- p.86
Chapter 4.3.5 --- Pathological changes of neuronal discharge pattern in MI --- p.88
Chapter 4.3.6 --- Pathological synchrony of MI neuronal population, especially during burst discharge --- p.89
Chapter 4.3.7 --- High frequency STN-DBS successfully suppresses synchronized burst discharge in MI --- p.89
Chapter 4.3.8 --- Pathological β-band oscillatory activity in MI-LFPs induced by 6-OHDA lesion --- p.90
Chapter 4.3.9 --- High frequency STN-DBS alleviates the β-band oscillation in MI-LFPs --- p.90
Chapter 4.3.10 --- Synchronized bursting discharge correlates with oscillatory activity --- p.91
Chapter 4.3.11 --- Pathological increased spike-LFP coherence level induced by 6-OHDA lesion --- p.92
Chapter 4.3.12 --- High frequency STN-DBS modulated the spike-LFP coherence properties --- p.92
Chapter 4.3.13 --- Antidromic spikes directly modulate the firing probability of CxFn --- p.93
Chapter 4.3.14 --- Antidromic spikes modulate the firing probability of INs and non-CxFn nearby. --- p.94
Chapter 4.3.15 --- The efficiency of antidromic cortical modulation depends on DBS frequency --- p.94
Chapter 4.3.16 --- Orthodromic vs. antidromic effect: which one is responsible for the beneficial effect of DBS? --- p.95
Chapter 4.3.17 --- Histology --- p.96
Chapter 4.4 --- Discussion --- p.96
Chapter 4.4.1 --- Origin of pathogenic rhythm in basal ganglia circuit --- p.96
Chapter 4.4.2 --- Suppression of oscillatory synchronization equals to therapeutic effects of DBS? --- p.97
Chapter 4.4.3 --- Beneficial effect of DBS corresponds to the topographic distribution of cortico-subthalamic projection. --- p.98
Chapter 4.4.4 --- What is the reason for a stochastic pattern of antidromic activation effect? --- p.99
Chapter 4.4.5 --- Desynchronization of pathological oscillatory rhythm by antidromic activation --- p.100
Chapter 4.4.6 --- Antidromic vs. orthodromic: which is the cause of the beneficial effects of DBS? --- p.101
Chapter 4.4.7 --- Wide propagation of antidromic effect by cortical horizontal circuits --- p.102
Chapter 4.4.8 --- Significance of antidromic cortical activation in during STN-DBS --- p.102
Chapter 4.4.9 --- Implication of antidromic activation effect on pathogenesis and treatment of PD --- p.104
Chapter 4.5 --- Figures --- p.105
CHAPTER 5 --- p.132
Impaired Synaptic Plasticity in the Primary Motor Cortex after Dopamine Depletion: Potential Role in Motor Memory Consolidation --- p.132
Chapter 5.1 --- Introduction --- p.132
Chapter 5.1.1 --- Characteristics of motor learning --- p.132
Chapter 5.1.2 --- Motor learning related cortical plasticity. --- p.133
Chapter 5.1.3 --- Dopaminergic signals in the primary motor cortex --- p.134
Chapter 5.1.4 --- Impaired cortical plasticity in PD --- p.135
Chapter 5.1.5 --- Objective --- p.136
Chapter 5.2 --- Materials --- p.136
Chapter 5.2.1 --- Animals --- p.136
Chapter 5.2.2 --- Chemicals --- p.136
Chapter 5.2.3 --- Equipment --- p.136
Chapter 5.3 --- Methods --- p.136
Chapter 5.3.1 --- Functional mapping of the forelimb territory in MI --- p.136
Chapter 5.3.2 --- Stereotaxic surgery --- p.137
Chapter 5.3.3 --- Forelimb-reaching Task. --- p.137
Chapter 5.3.4 --- In-vivo LTP Induction. --- p.138
Chapter 5.4 --- Results --- p.139
Chapter 5.4.1 --- Functional mapping of rat forelimb territory. --- p.139
Chapter 5.4.2 --- Morphologies of evoked field potential response --- p.139
Chapter 5.4.3 --- LTP of the early, monosynaptic plasticity within horizontal layer V MI --- p.140
Chapter 5.4.4 --- LTP of the late, polysynaptic plasticity within horizontal layer V MI --- p.140
Chapter 5.4.5 --- Impaired synaptic plasticity in MI after dopamine depletion --- p.140
Chapter 5.4.6 --- Learning curve of forelimb-reaching task --- p.140
Chapter 5.4.7 --- Physiologically enhanced cortical plasticity during motor learning --- p.141
Chapter 5.4.8 --- Dynamic modulation of cortical neuronal activities during motor skill learning. --- p.142
Chapter 5.4.9 --- Statistical analysis of ‘task related’ neuron’s modulation pattern. --- p.143
Chapter 5.4.10 --- Loss of dopamine modulation in the MI --- p.144
Chapter 5.5 --- Discussion --- p.144
Chapter 5.5.1 --- Distinguishing between monosynaptic and polysynaptic transmission --- p.144
Chapter 5.5.2 --- Artificially vs physiologically induced cortical plasticity. --- p.145
Chapter 5.5.3 --- Cortical synaptic plasticity interprets motor learning dynamics --- p.146
Chapter 5.5.4 --- Balance between neuronal recruitment and withdrawal in the consolidation stage --- p.147
Chapter 5.5.5 --- Dopamine’s involvement in mediating the cortical synaptic plasticity. --- p.148
Chapter 5.6 --- Figures --- p.150
Conclusion --- p.162
Abbreviations --- p.165
References --- p.168

碩士
淡江大學
電機工程學系碩士在職專班
96
Besides receiving input signal, the control system can receive feed-back signal and parameter setting signal, It can make system stably and precise to rotate with motor. Moreover, the parameter setting can adjust system coefficient that tuned and control motor output condition. And the parameter setting doesn’t need to adjust coefficient by external circuit. It just only inputs the parameter setting. In this paper, the Gain Tuning 1 and the Gain tuning 2 have the ability to tune motor setting when Parameter Setting inputs set into the Gain Tuning 1 and the Gain tuning 2. The main function of Gain Tuning 1 can boost or reduce input signal when input signal going through decode circuit. Therefore, they accomplish amplify or shrink input signal gain.Input signal and motor feedback signal both go through comparator to produce a contrast value. The Gain Tuning 2 tune signal is similar with the function of the Gain Tuning 1. The control system also used another input control signal and it will control more motors in one time by a frame signal.