Most electrolarynges do not allow hands-free use or pitch modulation. This study presents the potential of pattern recognition to support electrolarynx use by predicting fundamental frequency (F0) and voicing state (VS) from neck surface EMG and respiratory trace. Respiratory trace and neck surface EMG were collected from 10 normal, adult males (18-60 years old) during different vocal tasks. Time-domain features were extracted from both signals, and a Support Vector Machine (SVM) classifier was employed to model F0 and VS. An average mean-squared-error (MSE) of 8.21 ± 3.5 semitones2 was achieved for the estimation of vocal frequency. An average classification accuracy of 78.05 ± 6.3 % was achieved for the prediction of voicing state from EMG and 65.24 ± 7.8 % from respiratory trace. Our results show that pattern classification of neck-muscle EMG and respiratory trace has merit in the prediction of F0 and VS during vocalization.

Most electrolarynges do not allow hands-free use or pitch modulation. This study presents the potential of pattern recognition to support electrolarynx use by predicting fundamental frequency (F0) and voicing state (VS) from neck surface EMG and respiratory trace. Respiratory trace and neck surface EMG were collected from 10 normal, adult males (18-60 years old) during different vocal tasks. Time-domain features were extracted from both signals, and a Support Vector Machine (SVM) classifier was employed to model F0 and VS. An average mean-squared-error (MSE) of 8.21 ± 3.5 semitones2 was achieved for the estimation of vocal frequency. An average classification accuracy of 78.05 ± 6.3 % was achieved for the prediction of voicing state from EMG and 65.24 ± 7.8 % from respiratory trace. Our results show that pattern classification of neck-muscle EMG and respiratory trace has merit in the prediction of F0 and VS during vocalization.

Empathy is an essential prerequisite for the development and maintenance of close interpersonal relationships. Given that older adults are particularly vulnerable to the negative consequences of loneliness and social isolation, it is surprising that few studies have assessed empathy in this group. The current programme of research addressed this gap in the literature by testing competing predictions derived from Socioemotional Selectivity Theory and the Ageing-Brain Model for age-related sparing and impairment of empathy, respectively. Study 1 compared young (N = 80) and older (N = 49) adults?? self-reported levels of cognitive and affective empathy, and engagement in social activities. It was found that although affective empathy is spared, cognitive empathy is subject to age-related decline, and this decline mediates reductions in social participation. These data therefore affirmed the importance of further investigation into the nature, causes and potential consequences of age-related differences in empathy. Since disinhibition is one mechanism contributing to difficulty taking the perspective of another, and is known to increase with age, in Study 2, behavioural measures sensitive to inhibitory failure and to cognitive empathy were administered to young (N = 36) and older (N = 33) adults. One of the measures of cognitive empathy directly manipulated inhibitory demands, involving either high or low levels of self-perspective inhibition. The results indicated that older adults were selectively impaired on the high-inhibition condition, with cognitive disinhibition mediating this association. Study 2 therefore provided important evidence relating to one potential mechanism that contributes to age-related difficulties in perspective-taking. Studies 3 and 4 provided the first behavioural assessments of age-related differences in affective empathy by using electromyography to index facial expression mimicry. Study 3 found that young (N = 35) and older (N = 35) adults?? demonstrate comparable mimicry of anger, but older adults?? initial (i.e., implicit) reactions were associated with reduced anger recognition. Thus, to test the possibility that despite explicit recognition difficulties, implicit processing of facial expressions may be preserved in older adulthood, Study 4 compared young (N = 46) and older (N = 40) adults?? mimicry responses to subliminally presented angry and happy facial expressions. As predicted, the two groups demonstrated commensurate subconscious mimicry of these expressions. Taken together, these studies indicate that separate components of empathy are differentially affected by healthy adult ageing. Implications for competing perspectives of socioemotional functioning in older adulthood are discussed.

Empathy is an essential prerequisite for the development and maintenance of close interpersonal relationships. Given that older adults are particularly vulnerable to the negative consequences of loneliness and social isolation, it is surprising that few studies have assessed empathy in this group. The current programme of research addressed this gap in the literature by testing competing predictions derived from Socioemotional Selectivity Theory and the Ageing-Brain Model for age-related sparing and impairment of empathy, respectively. Study 1 compared young (N = 80) and older (N = 49) adults?? self-reported levels of cognitive and affective empathy, and engagement in social activities. It was found that although affective empathy is spared, cognitive empathy is subject to age-related decline, and this decline mediates reductions in social participation. These data therefore affirmed the importance of further investigation into the nature, causes and potential consequences of age-related differences in empathy. Since disinhibition is one mechanism contributing to difficulty taking the perspective of another, and is known to increase with age, in Study 2, behavioural measures sensitive to inhibitory failure and to cognitive empathy were administered to young (N = 36) and older (N = 33) adults. One of the measures of cognitive empathy directly manipulated inhibitory demands, involving either high or low levels of self-perspective inhibition. The results indicated that older adults were selectively impaired on the high-inhibition condition, with cognitive disinhibition mediating this association. Study 2 therefore provided important evidence relating to one potential mechanism that contributes to age-related difficulties in perspective-taking. Studies 3 and 4 provided the first behavioural assessments of age-related differences in affective empathy by using electromyography to index facial expression mimicry. Study 3 found that young (N = 35) and older (N = 35) adults?? demonstrate comparable mimicry of anger, but older adults?? initial (i.e., implicit) reactions were associated with reduced anger recognition. Thus, to test the possibility that despite explicit recognition difficulties, implicit processing of facial expressions may be preserved in older adulthood, Study 4 compared young (N = 46) and older (N = 40) adults?? mimicry responses to subliminally presented angry and happy facial expressions. As predicted, the two groups demonstrated commensurate subconscious mimicry of these expressions. Taken together, these studies indicate that separate components of empathy are differentially affected by healthy adult ageing. Implications for competing perspectives of socioemotional functioning in older adulthood are discussed.

Stair locomotion is one of the most difficult and challenging type of locomotion for older adults, with a high risk of fall and injuries. A major reason is that the neuromuscular system undergoes various changes through the aging process. The aim of this doctoral thesis is to study the age-related neuro-mechanical adjustments associated with stair locomotion and more specifically to investigate the interaction between neural and muscular changes in the plantarflexor muscles. To that aim, three main projects have been performed. The first two projects investigated the influence of age on spinal and supraspinal excitability when individuals stood at the bottom and the top of a 3-steps staircase and spinal excitability during stair locomotion. The third one focused on the age-related influence on the muscle-tendon behavior during stair locomotion. The result of the first project indicate a lower dependence on spinal pathway to control soleus motoneurons with a similar change observed in both age groups suggesting that healthy older adults preserved their ability to adjust postural control to environmental demands. The second project is the first to report the modulation of H-reflex amplitude in the plantarflexor muscles during stair ascent and descent in healthy young and older adults. This modulation likely reflects an increased role of descending inputs in controlling plantarflexor muscle activation during the stair gait cycle. However, similarly to the first project the modulation of the net excitatory inputs from group I afferents during the stair gait cycle does not seem to be influenced by healthy aging. The third project suggest that length changes of the Achilles tendon and lateral gastrocnemius (LG) fascicles favour the storage and recovery the tendon elastic strain energy over the muscle work, improving thereby the mechanical efficiency of stair ascent in young adults. In older adults, it seems that a different behavior is used to maintain a mechanical efficiency during stair ascent. In contrast, during stair descent, no difference was observed between age groups regarding the LG muscle-complex behavior despite some kinematics changes. In conclusion, this doctoral thesis indicates that despite some age-related structural and functional changes of the neuromuscular system, similar neural modulations occur during stair locomotion in young and healthy older adults. During stair ascent, a similar global pattern of change in length for the fascicle’s length and the modulation of the H reflex can be observed. However, during stair descent, H reflex modulation cannot be simply explained by the pattern of muscle length change. / Doctorat en Sciences de la motricité / info:eu-repo/semantics/nonPublished

abstract: The use of electromyography (EMG) signals to characterize muscle fatigue has been widely accepted. Initial work on characterizing muscle fatigue during isometric contractions demonstrated that its frequency decreases while its amplitude increases with the onset of fatigue. More recent work concentrated on developing techniques to characterize dynamic contractions for use in clinical and training applications. Studies demonstrated that as fatigue progresses, the EMG signal undergoes a shift in frequency, and different physiological mechanisms on the possible cause of the shift were considered. Time-frequency processing, using the Wigner distribution or spectrogram, is one of the techniques used to estimate the instantaneous mean frequency and instantaneous median frequency of the EMG signal using a variety of techniques. However, these time-frequency methods suffer either from cross-term interference when processing signals with multiple components or time-frequency resolution due to the use of windowing. This study proposes the use of the matching pursuit decomposition (MPD) with a Gaussian dictionary to process EMG signals produced during both isometric and dynamic contractions. In particular, the MPD obtains unique time-frequency features that represent the EMG signal time-frequency dependence without suffering from cross-terms or loss in time-frequency resolution. As the MPD does not depend on an analysis window like the spectrogram, it is more robust in applying the timefrequency features to identify the spectral time-variation of the EGM signal. / Dissertation/Thesis / M.S. Electrical Engineering 2012

Este trabalho visa desenvolver instrumentação de apoio para tratamentos de reabilitação de lesados medulares. Trata de propor um sistema de controle, seus componentes e operações para monitorar o avanço do esgotamento muscular, com o intuito de evitar a fatigamento total da estrutura muscular principalmente se sob efeitos de Estimulação Elétrica Neuro-Muscular (EENM). Foi desenvolvida pesquisa inicial sobre a atividade elétrica de grupos musculares clinicamente normais em contração voluntária e de grupos musculares paralisados sob efeito de eletro-estimulação. Em ambos casos, eletromiogramas de superfície (EMG) foram processados para verificar a manifestação mioelétrica da fadiga. Índices de contração muscular foram selecionados para utilização no sistema de controle da EENM. Serão apresentados os cálculos e rotinas computacionais utilizadas no projeto e simulação do Bloco de processamento digital (BPD), dedicado a monitorar os sinais do sistema de controle da EENM para avaliar o progresso do esgotamento muscular sobre os sinais de EMG, e quantificar o decréscimo da energia muscular em função do tempo em que a estrutura estiver sendo exercitada, contribuindo para monitorar a performance física tanto de indivíduos normais quanto de lesados medulares. / This work aims to develop support instrumentation to be used on Rehabilitation Treatments of medullar injured individuals. It proposes a control system, its components and operations to monitor muscular exhaustion, with the objective to avoid the total muscle structure fatigue mainly under effects of Neural-Muscular Electrical Stimulation (EENM). It was carried out an initial research into the electric activity of clinically normal muscle groups under voluntary contraction and of paralyzed muscles groups under electrical stimulation effects. In both cases, the surface electromyogram signals (EMG) have been processed to verify the myoelectric manifestation of fatigue. Muscular Contraction Indexes were selected to be used in the EENM Control System. It will be presented the calculus and computational routines used in the design and simulation of the Digital Processing Block (BPD), dedicated to monitor the signals of the EENM Control System to evaluate the progress of the muscular exhaustion in EMG signals, and quantify the muscular energy decrease as a function of the time when the structure is exercised, contributing to monitor the physical performance of normal and medullar injured individuals.

This study investigated the role of reinforcement schedule and instructional set in frontalis EMG training. The experiment consisted of four groups participating in 30 minute sessions on three consecutive days. Group conditions were intermittent feedback (alternating 100 second trials), continuous feedback, motivated control and no-treatment control. Excepting the no-treatment controls, each subject was instructed that extra credit points were available contingent on the number of seconds in criterion. An individual criterion based on each subject's initial baseline microvolt level was utilized.

Syfte Syftet med föreliggande studie var att studera korrelationen mellan EMG-respons och effektutveckling i samband med genomförande av knäböj. Metod Fyra manliga testpersoner deltog genom att utföra både knäböj 90° och djupa knäböj i en Smith-maskin som är ansluten till en Linear Encoder som möjliggör beräkning av effektutveckling. Samtidigt registrerades elektromyografisk aktivitet i musklerna Vastus lateralis, Hamstrings och Gluteus maximus. De utförde knäböj på olika relativa belastningsnivåer; 20, 40, 60, 80, 100% av 1RM. Resultat Resultaten visade inte en stark korrelation mellan medel-EMG och power, inte heller mellan medel-EMG och hastighet, dock indikerade resultaten mellan de sistnämnda en tendens till att en lägre EMG aktivitet uppstod vid de högre hastigheterna. En starkare korrelation kunde antydas mellan medel-EMG och belastning/kraft. Ingen tydlig skillnad mellan musklerna påträffades i förhållande till resultaten ovan. Dock var Hamstrings den muskeln som uppvisade den svagaste korrelationen. Slutsats EMG-aktiviteten var i stor grad densamma för respektive muskel trots olika belastningar, olika powervärden samt olika utföranden. Nervsystemet tycks därmed arbeta på ett särskilt sätt, oberoende av de andra parametrarna. Däremot kunde man se en svagare tendens för lägre EMG-aktivitet vid de högre hastigheterna. Hamstringsmuskulaturen var den som hade mest avvikande mönster, detta kan bero på det faktum att den har ett mer komplicerat förlopp än de andra två musklerna som testats.

Context. EMG (Electromyographic) signal is a response of a neuromuscular system for an electrical stimulus generated either by brain or by spinal cord. This thesis concerns the subject of onset detection in the context of a muscle activity. Estimation is based on an EMG signal observed during a muscle activity. Objectives. The aim of this research is to propose new onset estimation algorithms and compare them with solutions currently existing in the academia. Two benchmarks are being considered to evaluate the algorithms’ results- a muscle torque signal synchronized with  an EMG signal and a specialist’s assessment. Bias, absolute value of a mean error and standard deviation are the criteria taken into account. Methods. The research is based on EMG data collected in the physiological laboratory at Wroclaw University of Physical Education. Empty samples were cut off the dataset. Proposed estimation algorithms were constructed basing on the EMG signal analysis and review on state of the art solutions. In order to collate them with existing solutions a simple comparison have been conducted. Results. Two new onset detection methods are proposed. They are compared to two estimators taken from the literature review (sAGLR &amp; Komi). One of presented solutions seems to give promising results. Conclusions. One of presented solutions- Sign Changes algorithm can be widely applied in the area of EMG signal processing. It is more accurate and less parameter-sensitive than three other methods. This estimator can be recommended as a part of ensembled algorithms solution in further development. / <p>This is a Master Thesis completed in Double Diploma Programme. Dr. Jarosław Drapała was a supervisor from my maternal university. </p>