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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 27 (1989), S. 566-571 
    ISSN: 1741-0444
    Keywords: Averaging ; Computer-aided EMG ; Motor unit action potentials ; Template matching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A technique of extracting individual motor unit action potentials (MUAPs) from EMG signals by median averaging, a modification of an existing method, is presented. To compare different techniques of MUAP extraction, 89 MUAPs were recorded with a concentric needle electrode in the brachial biceps muscle of normal subjects and patients with nerve and muscle diseases. MUAPs were also extracted by another method, called split-sweep median averaging, in which alternate MUAP discharges are averaged independently in two computer buffers until the two averaged signals appear equal on visual inspection by the operator. The amplitude, area, area: amplitude ratio, duration and number of phases and turns of each extracted MUAP were determined by each technique. Overall, there was a strong correlation between all features of the MUAPs extracted by median and splitsweep averaging, although the latter method required, on average, twice as many MUAP discharges to produce acceptable signals. We thus conclude that median averaging is a fast and accurate method that requires relatively few MU discharges to extract MUAP signals from spurious background signals.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 23 (1985), S. 536-540 
    ISSN: 1741-0444
    Keywords: Action potentials ; Electromyography ; Motor unit action potentials ; Simulations ; Uptake area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A modified line source model was used to simulate single muscle fibre action potentials and their radial decline as measured using a single fibre (SF), concentric needle (CN) and macroelectromyography (EMG) electrode. The 90 per cent attenuation distance, defined as the distance from the fibre at which the peak-to-peak amplitude of the action potential declines to 10 per cent of its value measured near the fibre, was determined. For the CN and macro electrode this distance was 1·4 and 4·1 times, respectively, the distance measured for the SF electrode Based on the decline characteristics obtained from our simulations and experimental data reported in the literature, we inferred that in a normal human biceps muscle the spike component of CN MUAPs is produced mainly by the action potentials of the closest one-six muscle fibres. This inference was used to interpret the changes in MUAP amplitude seen by clinical EMG in neuromuscular diseases. The decline of action potential amplitude with distance from the electrode was least when recordings were made by the macro-EMG electrode. The three electrodes differed in their uptake area and thus recordings made with them provided complementary information about the motor unit architecture and the way it changes in neuromuscular diseases.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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