A literatura tem mostrado que as deteriorações proprioceptivas relacionadas ao envelhecimento podem ter consequências funcionais graves na realização de tarefas sensório-motoras como postura e marcha. A avaliação do limiar de percepção cinestésica é uma forma de avaliação da acuidade proprioceptiva e representa uma tarefa sensório-motora, com envolvimento de receptores e vias periféricas bem como de níveis superiores do sistema nervoso central. O presente estudo teve como objetivo avançar no método de quantificação proprioceptiva do tornozelo em jovens e idosos e foi dividida em dois capítulos. O primeiro capítulo investigou aspectos eletrofisiológicos corticais associados à percepção cinestésica do tornozelo. O protocolo experimental consistiu de aquisição de sinais eletrencefalográficos durante a avaliação do tempo de resposta à percepção de movimento passivo de tornozelo em velocidades baixa (0,5º/s) e alta (22º/s). Foram realizadas análises de potencial relacionado a evento (ERP do inglês Event-Related Potential) e de dessincronização e sincronização relacionados a evento (ERD/ERS do inglês Event-Related Desynchronization/Synchronization) na faixa beta (14 a 37 Hz). Os resultados mostraram atrasos nos tempos de resposta à percepção cinestésica dos idosos correlacionados aos atrasos de ativação cortical. O componente inicial do ERP (N1) foi menor e mais tardio em idosos e pode indicar uma chegada de influxo aferente proprioceptivo atrasada e de menor magnitude ao córtex. Os idosos também apresentaram maior ativação cerebral (maior ERD), o que pode representar um maior esforço cognitivo para processar as informações proprioceptivas. Além disso, após finalizada a tarefa sensório-motora na condição de velocidade alta de movimentação passiva, a inibição cortical (ERS) esteve atenuada em idosos em comparação aos jovens. Na condição de velocidade baixa, ERS foi observada em idosos, mas não em jovens, o que indica diferenças em níveis corticais entre os grupos etários na preparação para o movimento seguinte. O segundo capítulo deste trabalho foi motivado por estudos que mostraram que níveis ótimos de ruído elétrico podem melhorar a detecção e transmissão de sinais neurais, melhorando o desempenho de tarefas sensório-motoras. O presente estudo investigou se a aplicação de estímulo elétrico (EE) na região posterior das pernas melhora a percepção cinestésica e o controle postural de jovens e idosos. O limiar cinestésico foi avaliado pelo tempo de resposta à percepção de movimento passivo de tornozelo na velocidade de 0,5º/s. O controle postural foi avaliado durante a manutenção da postura ereta em três condições: olhos fechados, olhos abertos com movimentação periódica ou não-periódica do cenário visual (paradigma da sala móvel). Os resultados indicaram que a aplicação de EE na perna levou a uma redução do tempo de resposta à percepção cinestésica em adultos jovens e idosos. A amplitude de oscilação corporal também foi reduzida em ambos os grupos etários com a aplicação de EE, porém somente na condição de movimentação não-periódica da sala móvel. A partir destes resultados, conclui-se que a aplicação de EE promove melhoras no desempenho sensório-motor, que estão possivelmente relacionadas com uma melhor sinalização de receptores periféricos. Estes achados podem ter implicações clínicas importantes para indivíduos idosos, cujas alterações proprioceptivas e posturais os tornam mais suscetíveis a quedas / The literature has shown that age-related proprioceptive impairments may have serious functional consequences in performing sensorimotor tasks such as posture and gait. The evaluation of threshold for kinesthetic perception is a way to assess the proprioceptive accuracy and represents a sensorimotor task involving receptors and peripheral pathways as well as processing in upper levels of the central nervous system. The present study aimed to advance the method for quantifying ankle joint proprioception in older and young adults, and was divided into two chapters. The first chapter investigated the cortical electrophysiological aspects of evaluation of the threshold for ankle kinesthetic perception. The experimental protocol consisted of acquisition of electroencephalographic signals during the evaluation of the response time to the perception of passive ankle movement at low (0.5 °/s) and high (22°/s) velocities. Event-related potentials (ERP) and event-related desynchronization and synchronization (ERD/ERS) in the beta band (14-37 Hz) were analyzed. The results showed delayed response times to the kinesthetic perception in older adults with correlated delay in cortical activation. The initial ERP component (N1) had lower amplitude and was delayed in the older group and may indicate delayed and deficient arrival of afferent inputs to the cortex. Older adults also showed larger cerebral activation (larger ERD), which may represent higher cognitive efforts to process the proprioceptive information. In addition, after completing the sensorimotor task in the high velocity condition of passive foot movement, cortical inhibition (ERS) was attenuated in older adults when compared to young adults. In the low velocity condition, ERS was observed in older but not in young adults, which indicates differences at cortical levels between age groups during the preparation for the next movement. The second chapter of this study was motivated by results from studies that have shown that optimal levels of electrical noise can enhance the detection and transmission of neural signals, thereby improving the performance of sensorimotor tasks. The present study investigated whether the application of electrical stimulation (ES) in the posterior region of the legs improves kinesthetic perception and postural control in young and elderly. The kinesthetic threshold was assessed by the response time to the perception of passive ankle movement at 0.5º/s. Postural control was assessed during the upright stance in three conditions: eyes closed and with periodic and non-periodic movement of the visual scenario by means of a moving room paradigm. The results indicated ES applied over the legs led to a reduction in the response time to kinesthetic perception in young and older adults. The body sway amplitude was also reduced in both age groups with application of ES, but only in the condition with non-periodic room movement. From these results, it is concluded that the application of ES promotes improvements in sensorimotor performance and it is possibly related to improvements of receptor signaling. These findings may have important clinical implications for older adults, whose proprioceptive and postural changes make them more susceptible to falls

Lesões na medula espinhal atingem um grande número de pessoas, devido a traumas, doenças congênitas ou adquiridas. Para estes tipos de lesões não há cura e os indivíduos lesados medulares dependem de tratamento através de fisioterapia ou órteses que auxiliem na recuperação de possíveis funções perdidas. A Estimulação Elétrica Neuromuscular (EENM) tem sido pesquisada com essa proposta: reabilitar pessoas portadoras de lesão medular ou disfunções do aparelho locomotor. Muitos estudos já foram desenvolvidos na área de estimulação elétrica neuromuscular, avaliando a marcha, o ato de levantar-se ou outros movimentos. Um ponto em comum entre estes estudos é a preocupação com os efeitos fisiológicos da EENM, como por exemplo o gasto energético. Diante disto, o objetivo deste projeto foi avaliar os efeitos da EENM sobre o gasto energético de lesados medulares. Foi observado o consumo de oxigênio durante o repouso, a marcha e a recuperação. A avaliação proposta foi realizada por método indireto e as análises estatísticas foram realizadas através do teste ANOVA ONE WAY. Os resultados sugerem os voluntários tiveram recuperação fisiológica. Entretanto novas pesquisas são necessárias, com outras variáveis sendo avaliadas. / Lesions in the spinal cord affect a great number of individuals, either due to traumas or to congenital or acquired diseases. Such lesions are incurable, and the injured patients depend on physiotherapy or orthosis to aid in the recovery of lost functions. The Neuromuscular Electrical Stimulation (NMES) has been researched with this purpose: rehabilitating spinal cord injured patients, or those with motor system dysfunction. Several studies have already been developed in the field of neuromuscular electrical stimulation, assessing gait, the act of getting up or other everyday movements. All these studies bear something in common: the concern with the physiologic effects of NMES, such as the energy consumption. Hence, the objective of this project was to evaluate the effects of NMES on the energy cost of spinal injured patients. The consumption of oxygen was assessed during rest, gait and the recovery period. The proposed evaluation was made through indirect method, and the statistical analyses through the ANOVA ONE WAY test. The results to suggest that the volunteers had phisyological recovery. However, news reserchs there are needs, with others variable to be estimated.

Diabetic foot ulceration (DFU) is a known major complication of diabetes mellitus which contributes to lower extremities amputation. This study aimed to investigate the use of interventional devices either as a preventative or therapeutic strategy to improve clinical management of this pathology, as well as investigating the impaired function of endothelial progenitor cells in the diabetic condition. The first element targeted plantar callus formation among diabetic neuropathic (NRP) patients through the use of a SurroSenseRxTM biofeedback device. Reducing foot pressure with improved walking strategy in the 6 months study in diabetic neuropathy patients (n=20) appeared to minimise the size of non-ulcerative plantar callus (p < 0.05), potentially reducing future ulcer recurrence. The 2nd study focused on the use of a GekoTM electrical stimulation device to enhance DFU healing in 24 patients. Wounds were characterised as being neuroischaemic (NRI) or neuropathic (NRP) based on standard parameters adopted in the Manchester diabetes clinic. The device was worn by 11 intervention subjects and compared to 13 controls without any electrical stimulus. Results suggested healing and wound closure have potentially increased in participants with electrical stimulation. In addition, Neuropathy Disability Score (NDS) was improved among intervention patients compared to control (p < 0.0001). The 3rd, in vitro and mechanistic study focuses on the outgrowth of endothelial cells (OECs), abnormal angiogenic responses and inflammatory microenvironment which could contribute to impaired wound healing in diabetic patients. OECs were isolated from diabetic patients and healthy controls (HCs), characterised by immunohistochemistry and Polymerase Chain Reaction (PCR). The functions of the three OEC groups from NRI, NRP diabetic patients and healthy controls respectively were compared using in vitro proliferation, transwell migration and wound healing scratch assays, together with matrigel tube formation assays. Scratch assays showed 100% closure in HCs over 24 hours, while 86.6% closure was apparent in NRI vs 38.1% in NRP. Seahorse mitochondrial stress test was conducted and demonstrated mitochondrial dysfunction in NRP vs NRI vs HCs (p < 0.05). Western blot analysis showed a lack of ERK phosphorylation by NRP OECs and an up-regulation of plasma inflammatory cytokines (TNFa and IL-6) in diabetic samples vs HC (p < 0.0001), while the angiogenic factors ang-2, FGF-2, VEGF-D, HGF and IL-8, and nitric oxide bioavailability were all significantly reduced in diabetic samples vs HC (p < 0.05). The functional defects of the diabetic OECs were partially restored through glycomimetic (synthesis compounds for endothelial damage protection) treatment (p < 0.05). In summary, this study has highlighted areas worthy of future development both in terms of preventative and therapeutic strategies. With improvements in digital technology and the need to empower patients to take responsibility of their health and well-being as well as greater understanding of the cellular and molecular biological repair processes that may be exploited, there may be potentials to reduce the risk of future ulceration among patients using these novel approaches in the future.

Made available in DSpace on 2014-06-11T19:30:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-03-25Bitstream added on 2014-06-13T21:01:31Z : No. of bitstreams: 1 souza_mz_dr_rcla.pdf: 1750287 bytes, checksum: 1c591025405f7b78fb4b10883aebf64c (MD5) / Universidade Estadual Paulista (UNESP) / O objetivo deste estudo foi analisar e quantificar a participação das interleucinas (IL-4, IL-6, IL-10 e TNF-alfa) em animais que tiveram uma pata imobilizada e eletroestimulada por 1, 2 e 3 dias consecutivos, analisando-se a repercussão da hipocinesia focal sobre o conteúdo das proteínas musculares, bem como sobre parâmetros metabólicos como glicemia, insulinemia, glicogênio muscular, ácidos graxos livres, ácido ascórbico da glândula adrenal e da enzima creatina quinase (CK). A estimulação elétrica neuromuscular (EE, F=10Hz, T=0,4ms, i=5mA, 20 minutos diariamente), foi aplicada ao membro posterior de ratos, nos músculos Gastrocnêmio e Sóleo. Assim, ratos machos Wistar foram divididos em 7 grupos: controles (C), imobilizados por 1 dia (I1), imobilizados e eletroestimulados por 1 dia (IE1), imobilizados por 2 dias (I2), imobilizados e eletroestimulados por 2 dias (IE2), imobilizados por 3 dias (I3) e imobilizados e eletroestimulados por 3 dias (IE3). A Imobilização foi realizada através de uma órtese confeccionada sob medida em resina acrílica, mantendo o membro em posição a 90º pelos respectivos períodos experimentais. Os resultados demonstraram que a imobilização monosegmentar utilizada neste estudo desencadeou precocemente a proteólise muscular, alem de provocar respostas agudas nos sistemas diretamente relacionados com o fornecimento energético. Tais reações podem ser mediadas por algumas interleucinas, sobretudo a IL-6, que apresentou expressiva variação durante os períodos experimentais. Por outro lado, a eletroestimulação neuromuscular utilizada precocemente pode atenuar algumas destas respostas, minimizando o aspecto catabólico induzido pela imobilização. Assim, os resultados deste estudo leva a sugestiva de que as ações terapêuticas ou preventivas sobre as conseqüências deletérias da imobilização sobre os sistemas orgânicos devem ser adotadas precocemente. / The objective of the study was to evaluate and quantilfy the participation of interleukins (IL-4, IL-6, IL-10, and TNF) in rats that underwent paw immobilization and electrical stimulation for 1, 2, and 3 consecutive days, while analyzing the local hypokinesia repercussion on muscular protein content, as well as metabolic parameters of glycemia, insulineamia, muscular glycogen, free fatty acids, ascorbic acid, and createne kinase enzime (CK). The neuromuscular electrical stimulation (EE, F=10Hz, T=0,4ms, i=5mA, 20 minutes daily) was applied to the hindlimb of the animas over the soleus and gastrocnemius muscles. In this manner, albino male Wistar rats were distributed into 7 experimental groups: control (C), immobilized 1 day (I1), immobilized 1 day and electrostimulated (IE1), immobilized 2 days (I2), immobilized 2 days and electrostimulated (IE2), immobilized 3 days (I3) and immobilized 3 days and electrostimulated (IE3). The immobilization of the animals was achieved by an acrylic resin orthesis model which maintained the limb in the position of 90º during the respective experimental periods. The results demonstrated that the mono-segmental immobilization utilized during this study unchained muscular proteolysis prematurely, while also provoked acute responses in systems directly related to energy distribution. Such reactions can be measured by certain interleukins, especially the IL-6, which demonstrated an expressive variation during the experiemntal period. On the other hand, the neuromuscular electrical stimulation, when utilized prematurely, can diminish the occurance of some of these responses, minimizing the catabolic aspect induced by immobilization. Therefore, the results of this study indicate that theurapeutical or preventive actions over deleterious consequences of immobilization on organic systems should be adopted prematurely.

O procedimento cirúrgico de transplante de pele ou enxertia tem grande utilização em cirurgia plástica reparadora, e a influência de recursos terapêuticos na viabilidade deste, sob a ação da nicotina, ainda não está fundamentada. O objetivo do estudo foi avaliar a influência da estimulação elétrica de alta voltagem (EEAV) na integração de enxerto de pele total em ratos submetidos à ação da nicotina. Para tanto, foram analisados 60 ratos machos, adultos, da linhagem Wistar distribuídos aleatoriamente em 6 grupos de 10 animais: Grupo 1 (Sham) - animais submetidos ao procedimento cirúrgico de enxertia de pele; Grupo 2 - animais submetidos ao procedimento cirúrgico de enxertia de pele, e posteriormente, submetidos a EEAV anódica; Grupo 3 - animais submetidos ao procedimento cirúrgico de enxertia de pele, e posteriormente, submetidos a EEAV catódica; Grupo 4 - animais submetidos à ação da nicotina e, posteriormente submetidos ao procedimento cirúrgico de enxertia de pele Grupo 5- animais submetidos à ação da nicotina, posteriormente submetidos ao procedimento cirúrgico de enxertia de pele e em seguida submetidos à EEAV anódica; Grupo 6- animais submetidos à ação da nicotina e, posteriormente submetidos ao procedimento cirúrgico de enxertia de pele e em seguida submetidos à EEAV catódica. A aplicação da EEAV foi efetuada por sete dias (frequência de 10 Hz; limiar motor, 20 µs, e 100 µs), com início no terceiro dia após a cirurgia e após a retirada do curativo do enxerto. Foi analisada a porcentagem de contração tecidual do enxerto (software Image J®), circulação do enxerto, por meio de imagem infravermelha (FLIR® T300s). Também foi avaliada a espessura da epiderme, infiltrados inflamatórios e área de gap (Hematoxilina-eosina), imunohistoquímica para fator de crescimento do endotélio vascular (VEGF - Vascular Endotelial Growth Factor), e Fator VIII para contagem de número de vasos sanguíneos. Para a análise estatística foi aplicado o teste ANOVA seguido de Dunkan. O processamento dos dados foi efetuado pelo software SAS (Cary, NC), versão 9.3, sendo fixado o nível crítico de 5% (p<0,05). A estimulação elétrica de alta voltagem anódica promoveu maior integração do enxerto demonstrando menor porcentagem de contração tecidual, menor quantidade de infiltrados inflamatórios e maior quantidade de fator de crescimento do endotélio vascular, além de maior número de vasos sanguíneos neoformados Diante dos achados, pode-se concluir que a estimulação elétrica de alta voltagem pode influenciar positivamente na integração do enxerto de pele em ratos submetidos à nicotina. / The surgical procedure of skin grafting or grafting has great use in restorative plastic surgery, and the influence of therapeutic resources on the viability of this, under the action of nicotine, is not yet substantiated. The aim of the study was to evaluate the influence of high voltage electrical stimulation (EEAV) on the integration of total skin graft in rats submitted to nicotine action. For this purpose, 60 adult Wistar male rats randomly distributed in 6 groups of 10 animals were analyzed: Group 1 (Sham) - animals submitted to the surgical procedure of skin grafting; Group 2 - animals submitted to the surgical procedure of grafting of the skin, and later, submitted to anodic EEAV; Group 3 - animals submitted to the surgical procedure of skin grafting, and subsequently, submitted to cathodic EEAV; Group 4 - animals submitted to the action of nicotine and subsequently submitted to the surgical procedure of grafting of skin Group 5 animals submitted to the action of nicotine, later submitted to the surgical procedure of grafting of the skin and then submitted to anodic HVAC; Group 6 animals submitted to the action of nicotine and subsequently submitted to the surgical procedure of skin grafting and then submitted to cathodic HVAC. The application of EEAV was performed for seven days (frequency of 10 Hz, motor threshold, 20 ?s, and 100 ?s), starting on the third day after surgery and after removal of the dressing from the graft. The percentage of graft tissue contraction (Image J® software), graft circulation, was analyzed by means of infrared image (FLIR® T300s). The thickness of the epidermis, inflammatory infiltrates and gap area (Hematoxylin-eosin), immunohistochemistry for vascular endothelial growth factor (VEGF), and factor VIII for blood vessel count were also evaluated. For the statistical analysis the ANOVA test followed by Dunkan was applied. Data processing was performed by the SAS software (Cary, NC), version 9.3, and the critical level was set at 5% (p <0.05). Anodic high voltage electrical stimulation promoted greater graft integration, demonstrating a lower percentage of tissue contraction, a lower amount of inflammatory infiltrates and a greater amount of vascular endothelial growth factor, as well as a greater number of newly formed blood vessels. In view of the findings, it was concluded that high voltage electrical stimulation can positively influence the integration of the skin graft in rats submitted to nicotine.

La stimulation électrique fonctionnelle (SEF) est une des techniques utilisées pour la rééducation ou la suppléance fonctionnelle de déficiences motrices. Un stimulateur génère des impulsions électriques qui induisent des contractions des muscles paralysés, au travers des unités motrices toujours intactes. Aujourd'hui, les systèmes fonctionnant en boucle ouverte sont majoritairement utilisés. Ils permettent aux chercheurs d'évaluer hors-ligne de la SEF. Cependant, leur réglage reste basé sur un cycle essai-erreur ce qui est loin de simplifier la mise en œuvre de systèmes en boucle fermée. Dans cette thèse, nous proposons une méthode de prédiction en temps-réel du couple en fonction de l'EMG conduisant à une nouvelle modalité de contrôle de l'activation musculaire sous SEF. L'EMG évoquée (eEMG) donne une image de l'effet de la SEF sur l'activité musculaire et est ainsi impliquée à la fois dans l'estimation du couple en temps réel et le contrôle. Le couple articulaire peut être estimé par l'eEMG en utilisant un filtre de Kalman et un modèle NARX - RNN. Le facteur d'oubli du filtre de Kalman doit être soigneuse-ment choisi de même que les réglages du schéma de calcul. C'est une limitation en particulier quand lorsque qu'il n'y a aucune connaissance a priori sur la force générée par le sujet sous SEF. La méthode proposée NARX-RNN n'a pas ce défaut et offre de meilleures performances que le filtre de Kalman. L'estimation du couple basée eEMG est donc utilisée hors-ligne et en-ligne en temps réel. Les performances comparées des algorithmes ont été effectues sur sujets sains et sujets blessés médullaires. Par ailleurs, le système temps-réel de contrôle de l'activation musculaire basé EMG a été développé sur la technologie sans fil Vivaltis. Enfin, afin de proposer un contrôle de plusieurs muscles, le concept de synergie a été utilisée pour estimer les activations musculaires cibles à partir d'un couple articulaire désiré. Les niveaux de synergie moyenne ont été utilisés pour valider l'extraction d'activation sur le sujet non inclus dans le calcul de la moyenne. L'erreur d'estimation est de 9.3% sur l'ensemble des sujets. Ces résultats vont dans le sens d'un contrôle d'une neuroprothèse basé synergie. En effet la combinaison des eux contributions de la thèse ouvre des perspectives nouvelles de modalité de contrôle de la SEF. / Functional electrical stimulation (FES) is one of existing rehabilitationtechniques to restore lost motor functions for motor-impaired subjects. Thestimulator generates electrical pulses to drive artificial contractions of theparalysed muscles, through activating intact motor units. Currently open-loopFES system is the most frequently used. The data acquired from the open-loop FESwould help researchers to make off-line analysis for evaluating performance ofFES systems. However, it should go through a trial and error manner, which isfar from facilitating a implementation of real-time closed-loop FES system.In this thesis, we propose and develop a method for real-time EMG-feedback torqueprediction and muscle activation control toward new modality in FES.The evoked electromyography (eEMG) which can reflect electrical muscleactivities under FES, is involved in both offline and real-time FES-inducedtorque estimation and muscle control systems. FES-induced joint torque can beestimated/predicted with eEMG by employing both Kalman filter and NonlinearAuto-Regressive with Exogenous (NARX) type recurrent neural network (RNN). Theforgetting factor of Kalman filter should be properly selected in advance andalso with proper computational settings. It is a limitation for some casesespecially when we do not have prior knowledge of new subject regarding expectedmuscle response intensity induced by FES. The proposed NARX-RNN does not sufferfrom such computational setting problems and also shows better estimation/prediction performances than that of Kalman filter.Evoked EMG based torque estimator is exploited from off-line situation toonline real-time system. Recursive Kalman filter and NARX-RNN are implementedfor real-time torque estimation/prediction with evoked EMG. The performance wasverified both in able-bodied and spinal cord injured subjects. Furthermore, real-time EMG-feedback muscle activation control in FES system is developed togetherwith wireless Vivaltis stimulator for specifying directly muscle activationinstead of conventionally specifying stimulation pattern.Toward natural multiple muscles control with multi-channel FES, muscle synergyconcept was introduced for inverse estimation of muscle activations from desiredjoint moment. The averaged synergy ratio was applied for muscle activationestimation with leave-one-out cross validation manner, which resulted in 9.3%estimation error over all the subjects. This result supports the common musclesynergy-based neuroprosthetics control concept. By combining this inverse estimation of muscle activations together with real-time EMG-feedback muscle activation control, it would open a new modality toward muscle synergy-basedmulti-muscle activation control in FES.

We describe the development of a cyber-physical system (Rehab Tracker) for improving patient compliance with at-home physical rehabilitation using neuromuscular electrical stimulation (NMES) therapy. Rehab Tracker consists of three components: 1) hardware modifications to sense and store use data from an FDA-approved NMES therapy device and provide Bluetooth communication capability, 2) an iOS-based smartphone/tablet application to receive and transmit NMES use data and serve as a conduit for patient-provider interactions and 3) a back-end server platform to receive device use data, display compliance data for provider review and provide automated positive and remedial push notifications to patients to improve compliance. This system allows for near real-time compliance monitoring via a secure web portal and offers a novel conduit for patient-provider communication during at-home rehabilitation to improve compliance. The system was tested in patients (n=5) who suffered anterior cruciate ligament rupture and surgical repair to provide proof-of-principal evidence for system functionality and an initial assessment of system usability. The system functioned as designed, recording 89% of rehabilitation sessions. Thus, Rehab Tracker is a functionally correct system with the potential to be used as a tool for studying NMES and mobile communication methodologies at scale and improving compliance with at-home rehabilitation programs.

The use of neuromuscular electrical stimulation (NMES) for the treatment of swallowing disorders has become increasingly popular, yet little is known about its long-term effects on muscle physiology. This study indirectly assessed suprahyoid muscle physiology using electromyography (EMG) during a jaw-opening task that was completed before training, immediately after training, and two-weeks after training. Comparisons were made in muscle performance between control participants who engaged in effortful swallowing training and participants who received conjunctive NMES during effortful swallow training. All participants completed four weeks of swallowing exercises conducted five days a week (20 sessions) and consisting of 120 swallows each session. Results revealed that participants collectively improved their peak force production following training, but peak force and EMG median frequency did not vary as a function of training method. The observed high variability in median frequency between trials in addition to the documented improvement in function without a measured change in physiology suggests the need to consider alternate electrode placements during EMG or other tools of assessment. These findings suggests that both effortful swallow training and long-term conjunctive NMES with effortful swallowing improves jaw-opening strength of healthy adults, though adding NMES to the treatment was no more effective than training without it. Further research is necessary to determine the effects of long-term NMES training on swallowing physiology in vivo using other indirect measurements, or direct measurements such as muscle biopsy if possible.

Problem investigated: Chronic wounds are not only a major burden to the patient arising from general pain and discomfort but also generate economic costs to both these individuals and the health care system. Various electrical stimulation regimes have been employed to study the effects of electrical stimulation on wound healing both in vivo and in vitro. In was hypothesised that electrical stimulation using various waveforms can modulate cell function, particularly cell migration. The aim of this thesis was to study the effects of electrical stimulation on cellular migration, in particular endothelial cells and fibroblasts, key cell types involved in wound healing. The impact of collagen matrix on cell migration was also assessed. Methods: Cells were seeded on either glass or collagen I substrate and stimulated with various electrical regimes via platinum electrodes connected to a constant current source. Cell migration was accessed by manual tracking of cell nuclei over a period of 3 hours from digital time-lapse images acquired during stimulation. Data from cell tracking were analysed for directional migration, migration rates and mean square displacement. Results: No directional cell migration for both endothelial cells and fibroblasts were observed when stimulated with either alternating or biphasic currents. However, surface substrate had impacted on cell motility with opposite effects being observed for the two cell types. Endothelial cells tended to migrate at a faster rate on collagen I substrate than on glass, compared with fibroblasts, which displayed a slower rate of migration on collagen I substrate. Significant changes in mean square displacement of biphasic current stimulated cells on collagen I substrate compared to unstimulated cells were also observed. Conclusion: This thesis has illustrated cell migration can be modulated by electrical stimulation, in particular asymmetric biphasic current. It has also been demonstrated surface substrate can impact cell migration.

Spinal cord injury is a devastating neurological disorder partially characterized by a loss of motor function below the lesion. The dramatic loss of activity results in muscle atrophy and slow-to-fast transformation of contractile elements, producing smaller, weaker and more fatiguable muscles. Functional electrical stimulation (FES), has been proposed in order to induce muscular activity and reverse these changes. FES has primarily been applied in the periphery, either at the surface or implanted in or around a nerve or muscle. Although this can excite nervous tissue and produce muscular contractions, these systems often produce reversed recruitment of motor units leading to inappropriate force generation and increased fatigue. We applied intraspinal microstimulation (ISMS) through fine microwires implanted into the spinal cord of rats. Electrical stimulation through these microwires caused contractions of the quadriceps muscles in both acute and chronically spinalized animals. We showed that muscle recruitment is significantly more gradual with ISMS in intact rats compared to that produced by a standard nerve cuff. Our results further showed that this was due to preferential activation of fatigue resistant muscle fibers. Given this more orderly recruitment of motor units by ISMS, we tested the muscle phenotypes produced by ISMS or nerve cuffs after chronic stimulation. Surprisingly, over a 30 day stimulation period the quadriceps muscles chronically activated by either daily ISMS or nerve cuff stimulation underwent similar fast-to-slow transformations in fiber type and functional properties. This indicates that the recruitment order of motor units does not play the only role in determining the muscle phenotype. Other factors such as the total daily time of activity may be critically important to the phenotypic outcome of skeletal muscle. Finally, we demonstrated that quadriceps force recruitment by ISMS was unchanged following the 30 day stimulation period. In addition, 30 days of chronic ISMS did not cause observable damage in the spinal cord beyond that incurred by the implantation of sham microwires. These studies advance our understanding of the force recruitment properties, neuromuscular plasticity and damage incurred by ISMS and move us closer to developing a clinically viable ISMS procedure.