Calculation of extracellular potentials produced by an inclined muscle fibre at a rectangular plate electrode

Dimitrova, Nonna A.; Dimitrov, Alexander G.; Dimitrov, George

doi:10.1016/s1350-4533(99)00087-9

Cited by 29 publications

(20 citation statements)

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“…The bers within a parallel muscle are approximately parallel to the long axis of the muscle ber length [8] whereas the bers within a pinnate muscle form an angle to the long axis of the muscle ber length [8,9]. In addition, the detection system can also be inclined with respect to the muscle ber direction [1,10].…”

Section: Introductionmentioning

confidence: 99%

Classification of the Systems Used in Surface Electromyographic Signal Detection according to the Degree of Isotropy

Messaoudi

Bekka

Belkacem

2018

ABE

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Surface electromyographic (EMG) signals are known to be strongly in uenced by anatomical, physiological and detection system parameters. Among the detection system parameters, we are interested in the effect of muscle ber inclination on the electrode arrangement. The purpose of this study was to determine the best and the worst orientation of the electrodes arranged in nine detection systems relative to the muscleber direction and also to classify the investigated systems according to their degree of isotropy. The study was based on simulated surface EMG (sEMG) signals generated in a cylindrical multilayer volume conductor. The orientation of electrodes with respect to the ber direction was de ned by the ber inclination angle (FIA). For each detection system, the mean power (MP) of the simulated signals was computed at different FIAs and used as a basis for evaluating the effect of muscle ber inclination. We showed that for the FIA range of 0-180 , approximately isotropic systems had three positions to record sEMG signals under good conditions (MP was maximum). However, longitudinal and transversal highly anisotropic systems had two and one positions, respectively, at which sEMG signals were detected under good conditions. We showed also that the degree of isotropy of the nine detection systems investigated was less affected by the increase in muscle and fat thicknesses. However, with an increase in inter-electrode distance (IED), the degree of isotropy of approximately isotropic systems decreased while the degree of isotropy of highly anisotropic systems increased.

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Section: Introductionmentioning

confidence: 99%

Classification of the Systems Used in Surface Electromyographic Signal Detection according to the Degree of Isotropy

Messaoudi

Bekka

Belkacem

2018

ABE

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“…4,5,[7][8][9]11 It should be noted, however, that such studies do not provide evidence to support this assumption, since the skin-electrode interface properties are not taken into account. In related application fields, the electrode has been modeled more precisely and the impedance between the electrode and the skin has been explicitly considered.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Potential Averaging over the Finite Surface of a Bioelectric Surface Electrode

et al. 2009

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Abstract-Most bioelectric signals are not only functions of time but also exhibit a variation in spatial distribution. Surface EMG signals are often ''summarized'' by a large electrode. The effect of such an electrode is interpreted as averaging the potential at the surface of the skin beneath the electrode. We first introduce an electrical equivalent model to delineate this principle of averaging. Next, in a realistic finite element model of EMG generation, two outcome variables are evaluated to assess the validity of the averaging principle. One is the change in voltage distribution in the volume conductor after electrode application. The other is the change in voltage across the high impedance double layer between tissue and electrode. We found that the principle of averaging is valid, once the impedance of the double layer is sufficiently high. The simulations also revealed that skin conductivity plays a role. High-density surface EMG provided experimental evidence consistent with the simulation results. A grid with 120 small electrodes was placed over the thenar muscles of the hand. Electrical nerve stimulation assured a reproducible compound muscle response. The averaged grid response was compared with a single electrode matching the surface of the high-density electrodes. The experimental results showed relatively small errors indicating that averaging of the surface potential by the electrode is a valid principle under most practical conditions.

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“…The proposed method is based on a few fast and precise models (DIMITROV and DIMITROVA, 1998;DIMITROVA et al, 1999;2001). One of them (DIMITROV and DIMITROVA, 1998) was intended for calculation of MUPs produced by N fibres (parallel to the skin surface) and detected monopolarly by a point or rectangular plate electrode, if the lAP time course (~0) was identical in all muscle fibres, then the MUPs could be considered as the output of a linear timeshiftinvariant system and could be represented through a single convolution: where K Ka,,(~i/16~a,,) ; Ka, , is an anisotropy factor, i.e.…”

Section: Fundamentals For Modellingmentioning

confidence: 99%

“…Models of muscle potential should reflect the transmembrane sources which are due to the presence of two waves of excitation (that originate at the endplate and propagate to the ends of every fibre), geometrical relations between recording electrodes and active fibres, as well as volume conductor properties. A simplified simulation of the transmembrane sources through one or two dipoles (GEORGE, 1970;FUGLEVAND et al, 1992 ) or tripoles (ROSENFALCK, 1969), gives way to analytical presentation of actual shapes of the intracellular actual potential (lAP) (ROSENFALCK, 1969;TRAYANOVA and DIMITROV, 1982;NANDEDKAR et al, 1985;GOOTZEN, 1990;LATEVA et al, 1996; Correspondence should be addressed to Dr N. A. Dimitrova; e-marl: ngdim@iph.bio DIMITROVA, 1998;DUCHENE and HOGREL, 2000;DIMITROVA et al, 1999). Muscle fibres are usually assumed to be parallel to the skin surface (FUGLEVAND et al, 1992;GOOTZEN, 1990;LATEVA et al, 1996;DIMITROV and DIMITROVA, 1998;MERLETTI et al, 1999;DUCHENE and HOGREL, 2000) and sometimes to be inclined to it (DIMITROVA et al, 1999) or curved (DIMITROV and DIMITROVA, 1980).…”

Section: Introductionmentioning

confidence: 99%

“…Then the extracellular potentials produced by a single muscle fibre (SMFP) can be expressed through convolution in temporal (LATEVA et al, 1996;DIMITROV and DIMITROVA, 1998;DIMITROVA et al, 1999) or spatial (DUCHENE and HOGREL, 2000) domain, in contrast to the spatial domain, calculation of motor unit potential (MUP) or evoked muscle response in the temporal domain can be reduced to a single convolution (DIMITROV and DIMITROVA, 1998) even when propagation velocity is not equal in individual fibres. To reduce noise and to minimise activity from other muscles, bipolar electrodes or multielectrodes with a great number of leading surfaces are used in detecting muscle potentials.…”

Section: Introductionmentioning

confidence: 99%

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Calculation of spatially filtered signals produced by a motor unit comprising muscle fibres with non-uniform propagation

Dimitrova

Dimitrov

2001

Med. Biol. Eng. Comput.

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Simulation of actual muscle potentials is necessary to understand processes that underlie changes in electromyographic signals. The work reported aims to analyse existing methods and suggest new ways of calculating precisely the signals (MUS) detected by a multielectrode from motor units (MUs) consisting of homogeneous or inhomogeneous (functionally and geometrically) fibres. Simulation (based on cable equations) of intracellular action potential (IAP) in a muscle fibre with a moderate geometrical inhomogeneity demonstrates that considerable changes in propagation velocity (more than 3.5 times) are accompanied by insignificant changes in the IAP amplitude (< 5%) and IAP shape in the temporal domain. MUS can therefore be considered as the output signal of a timeshift-invariant system whose input signal is the first temporal derivative of the IAP. As a result, calculation of MUS is reduced to a single convolution in the case of muscle composed of both homogeneous and inhomogeneous fibres. The suggested approach is valid for simulation of recordings obtained with points or rectangular plates leading off surfaces from muscles consisting of fibres that are parallel or inclined to the skin surface. The MUS terminal phases are prolonged because of fibre inhomogeneities. The presence of geometrical inhomogeneities results in additional positive-negative phases in MUS.

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Calculation of extracellular potentials produced by an inclined muscle fibre at a rectangular plate electrode

Cited by 29 publications

References 4 publications

Classification of the Systems Used in Surface Electromyographic Signal Detection according to the Degree of Isotropy

Classification of the Systems Used in Surface Electromyographic Signal Detection according to the Degree of Isotropy

Evidence of Potential Averaging over the Finite Surface of a Bioelectric Surface Electrode

Calculation of spatially filtered signals produced by a motor unit comprising muscle fibres with non-uniform propagation

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