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1

Method of automatic recognition and other solutions used in new computer program for full decomposition of EMG signals

Młoźniak D., Piotrkiewicz M.

Biocybernetics and Biomedical Engineering

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2015

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Vol. 35, no. 1

22--29

EN

The analysis of electromyographic signals can be very time consuming. In designing a program for EMG signal analysis, there are two competing factors: the accuracy of the final result and its speed. In scientific work, accuracy is the most important factor. All of the existing decomposition programs used in neurophysiology require a final phase of manual corrections, if reliable results are to be obtained. This phase is considerably longer than the phase of automatic recognition. The solutions presented below, used in our new MUR program, allow for the accurate decomposition of complex EMG signals in a reasonable amount of time. The decomposition is performed interactively with optimal time division between automatic and manual tasks. All of this is achieved through a simple method of automatic recognition with the use of the modified coefficient of determination and the method of multiple subtractions of potentials.

2

Variability and plasticity of motor unit properties in mammalian skeletal muscle

Celichowski J., Krutki P.

Biocybernetics and Biomedical Engineering

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2012

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Vol. 32, no. 4

33-45

EN

In the majority of mammalian skeletal muscles, contractile properties of motor units are variable and three main types of these units can be distinguished. The present review summarizes: results of studies of motor unit properties in the medial gastrocnemius muscle and their variability in two species, cats and rats, and studies on differences of motor unit properties in two genders. Moreover, plasticity of motor unit properties in rat medial gastrocnemius evoked by two kinds of spinal cord injury, total transection and hemisection, is reviewed, and effects of two types of training, treadmill locomotor and whole-body vibration training, are summarized. Finally, changes in the motor unit properties during the aging process are presented.

3

Motor unit contractions evoked by stimulation with variable interpulse intervals

Krutki P., Celichowski J., Raikova R.

Biocybernetics and Biomedical Engineering

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2012

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Vol. 32, no. 3

29-42

EN

During natural contractions motor units (MUs) are activated by variable frequency discharge patterns of motoneurones. The aim of this review was (1) to discuss differences between tetanic contractions developed at constant and random frequencies of pulses; (2) to show results of mathematical decomposition of these tetani into series of twitch-shaped responses to individual pulses; (3) to indicate that it is possible to predict the tetanic force of a MU with high accuracy by using regression equations derived on a basis of the relationships between the parameters of the decomposed twitches and the force level at which the next response begins.

4

Diagnozowanie schorzeń nerwowo-mięśniowych za pomocą sieci neuronowych w oparciu o skalogramy potencjałów czynnościowych

Dobrowolski A., Wierzbowski M., Tomczykiewicz K.

Przegląd Elektrotechniczny

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2009

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R. 85, nr 11

99-104

PL

W artykule przedstawiono nową metodę diagnozowania chorób nerwowo-mięśniowych opartą na analizie skalogramów wyznaczonych za pomocą falek Symlet 4. Z otrzymanych skalogramów wyekstrahowano 5 cech, umożliwiających klasyfikację do grupy miogennej, neurogennej lub prawidłowej za pomocą sztucznych sieci neuronowych różnych typów. Zastosowano perceptron progowy, perceptron wielowarstwowy oraz sieć SVM w wersji liniowej.

EN

The paper presents a new method of diagnosis of neural-muscle disorders based on analysis of scalograms of action potentials determined by using the ‘Symlet 4’ wavelet technique. The scalograms provide 5 features that allow artificial neural network classifier to distinguish between three classes: myogenic, neurogenic or normal. The neural networks utilized were single-layer perceptron, multilayer perceptron and linear support vector machine.

5

The tetanic depression in unfused tetani of fast motor units in mammalian muscle

Celichowski J.

Biocybernetics and Biomedical Engineering

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2005

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Vol. 25, no. 4

27-35

EN

Tetanic depression is a phenomenon that limits the force of unfused tetani in contractions evoked at unstable stimulation frequencies. In our experiments this phenomenon was visible in tetani evoked at two frequencies of stimulation: the lower immediately followed by the higher one. The force at the higher stimulation frequency was evidently depressed in relation to the force achieved during the control constant-frequency stimulations. This depression concerned the fast motor units and it was not observed in the slow units. The tetanic depression was initially found in the rat medial gastrocnemius muscle. However, it is not clear whether this phenomenon is specific only to the rat muscle or it concerns all mammals. Therefore, in the subsequent series of experiments, the tetanic depression was investigated in the motor units of the feline medial gastrocnemius, and the effect was also observed in all fast units. The maximum evoked depression exceeded 50% of the control values. Moreover, the analysis of the relationship between the amplitude of the tetanic depression and the degree of the tetanic fusion revealed that the strongest amplitude of depression was observed in the middle-fused tetani (with the fusion index in the range 0.5-0.7). The third experimental series proved that the tetanic depression could be visible in tetani evoked at a progressively increasing frequency of stimulation. Moreover, it was found that the effect of the force decrease could result from the prolongation of only one, the first interpulse interval. The amplitude of this decrease exceeded 20% of the control values. Summarizing, the tetanic depression is a phenomenon influencing the force of unfused tetani of the fast motor units at an increasing stimulation frequency. The depressive effect is present in various species of mammals, probably, including human. The amplitude of the depression depends on the fusion of the tetanic contraction. The physiological significance of tetanic depression is closely related to reduction of the importance of the motoneuronal firing rate.

6

Computer system for identification and analysis of motor unit potential trains

Mazurkiewicz Ł., Piotrkiewicz M.

Biocybernetics and Biomedical Engineering

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2004

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Vol. 24, no. 3

15-23

EN

The paper presents a computerized system for identification and analysis of electromyographic signals recorded from muscle by needle electrodes. The system provides information on human motoneuron activity as time sequences of identified single motor unit potentials. This information can afterwards be statistically processed to obtain data on motoneuron properties in healthy subjects and in some neuromuscular diseases. A special attention has been paid to the description of the methods of spike identification, including extraction of spikes from the signal and automatic classification, which is based on the statistical pattern recognition approach. The system described is also an example of adaptation of modern computer technology for biomedical research.

7

Estimation method of the number of motor units by processing mass electromyogram

Yoshida M.

Biocybernetics and Biomedical Engineering

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2000

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Vol. 20, no. 3

65-75

EN

The new method of estimating the number and the size of active motor units by processing mass electromyogram (EMG) is devised. This method is based on a model of mass EMG generation, which is founded on the knowledge of the mode of motor units activities. This model is described as follows. (1) Mass EMG is the sum of all active motor units action potential trains. (2) An input of each motor unit is a statistically independent random pulse train. (3) Motor units are divided into groups by their threshold force for recruitment. (4) The firing rate is the function of force. By using the theory of the shot noise, the number and the size of motor units of each group are expressed as a function of the second and fourth moment of mass EMG and firing rate. This estimation starts from the lowest threshold force group. This method is applied to the human brachialis muscle and the human extensor digitorum communis muscle. The estimated results agree to the size principie and the physiological knowledge of the relation between the threshold force and the number of motor units. This agreement confirms the propriety of this estimation method.

PL

W pracy zaproponowano nową metodę oceny liczby i rozmiaru czynnych jednostek ruchowych mięśnia dzięki przetworzeniu zbiorczego sygnału elektromiograficznego (EMG). Metoda ta jest oparta na modelu generacji sygnału EMG, który został zbudowany na podstawie wiedzy o cechach czynności jednostek ruchowych. Przyjęto następujące założenia: (I) zbiorczy sygnał EMG jest sumą potencjałów czynnościowych aktywnych jednostek ruchowych, (II) sygnał wejściowy każdej jednostki ruchowej jest statystycznie niezależnym impulsowym ciągiem probabilistycznym, (III) jednostki ruchowe różnią się wartością siły, przy której są rekrutowane, (IV) częstość generowanych przez jednostki ruchowe potencjałów czynnościowych jest zależna od poziomu siły. Używając teorii procesów stochastycznych określono liczbę i rozmiar jednostek jako funkcje drugiego i czwartego momentu EMG i częstości generacji potencjałów czynnościowych. Metodę tę zastosowano do analizy czynności mięśni człowieka. Uzyskane rezultaty są zgodne z zasadą rozmiaru i wiedzą o relacjach pomiędzy siłą i liczbą rekrutowanych jednostek mięśnia. Zgodność ta potwierdza słuszność metody.