A technique has been developed which enables the decomposition separation of a myoelectric signal into its constituent motor unit action potential trains. A novel validation approach for high density surface emg. This is the current preferred term rather than motor unit action potential because the mup is not an action potential. It is a compound potential derived from the mf action potentials aps of a mu. Morphology n motor unit action potential muap varies based on muscle, age n duration often shorter in proximal muscles n amplitude greater in adults than children bigger fibers n muap size larger in older individuals probably from dropout of motor units with some normal reinnervation n phases. To test motor unit stimulation, electrodes are placed extracellularly on the skin and an intramuscular stimulation is applied. Multichannel intramuscular and surface emg decomposition. Properties of the motor unit action potential shape in proximal and distal muscles of the upper limb in healthy and poststroke individuals. Here dominant motor unit action potentials are extracted from the emg signals via template matching based decomposition method.
Technologies for decomposing the electromyographic emg signal into its constituent motor unit action potential trains have become more practical by the advent of a noninvasive methodology using. Motor unit structural change post stroke examined via. The electrical changes generated by activity of the mu can be acquired and amplified by electrodes located in muscle mass and these changes can be recorded and edited using electromyographic emg devices. Sensor sites rendered varying motor unit yields throughout the surface of a muscle. It consists of a multichannel via one electrode myoelectric signal recording procedure, a data compression algorithm, a digital filtering algorithm, and a hybrid visualcomputer decomposition scheme. To characterize mu reorganization, an estimate of the motor unit action potential muap amplitude was derived using spike triggered averaging of the semg signal. The surface emg was synthesized as the sum of all motor unit action potential. Motor unit pool organization examined via spiketriggered. Measuring the accuracies of motor unit firing times and. Preferred sensor sites for surface emg signal decomposition.
Figure 1 illustrates the decomposition of a muap into its coarse, sy, and detail components, dj. Mus met the 90% accuracy criteria from the reconstructandtest with sta procedures then applied. Under normal circumstances, this results in all muscle fibers of the motor unit being activated and depolarizing more or. Validating motor unit firing patterns extracted by emg. Special studies such as precision decomposition have. This advancement has widespread appeal among researchers and clinicians because. When a motor neuron depolarizes to threshold, a nerve action potential is generated and propagates down the axon. Their results were in total agreement for 479 motor unit action potential classifications belonging to five motor unit action potential trains. The algorithm uses a continuously updated template matching routine and firing statistics to. The effects of local forearm muscle cooling on motor unit. Model for decomposition of the motor unit action potential. The representation of the changes generated by a mu is the so called motor unit action potential. Online intramuscular emg decomposition with varying number of active motor units.
Motor unit potential an overview sciencedirect topics. The waveform is dictated by the inherent properties of the motor unit and the spatial relationships between the needle and individual muscle fibers. The plotted peaktopeak motor unit action potential pp muap amplitudes mv derived from the precision decomposition pd iii algorithm and spike trigger average sta procedure in relation to recruitment threshold expressed as a percentage of the maximal voluntary contraction %mvc for. A motor unit consists of a group of individual muscle fibers that are activated by a single motor neuron. Wavelet domain feature extraction scheme based on dominant motor unit action potential of emg signal for neuromuscular disease classification abstract. B the denoised signal based on a synthetic emg signal. Because all muaps are not uniquely represents a class. Action potentials were extracted into single firing events of mus from the 4 separate emg signals, sampled at 20 khz and filtered with a bandwidth of 20 hz to 9. Muaps typically last from one to several milliseconds, although their exact size and shape depend on the where the electrode is located with respect to. A model for decomposition of the motor unit action potential muap which finds an optimal fit of a set of simulated singlefibre action potentials ssfaps to the original muap is tested. This algorithm was designed for decomposing surface emg signals into their individual motor unit action potential amplitude trains muap. After the action potential is transmitted across the neuromuscular junction, an action potential is elicited in all of the innervated muscle fibers of that particular motor unit.
Multichannel intramuscular and surface emg decomposition by convolutive blind source. Motor unit potential trains mupts extracted via electromyographic emg signal decomposition can aid in the diagnosis of neuromuscular disorders and the study of the neural control of movement. A the motor unit action potential template waveforms of all motor unit action potential train decomposed from the signal shown in b. Pdf online intramuscular emg decomposition with varying. Emg signals are composed of motor unit action potential muap trains, the muap. A motor unit consists of one alpha motor neuron and all the muscle fibres it innervates muscles differ in the number of motor units that they contain, and how many muscle fibres are within each unit innervation ratio. The motor unit action potential muap is the sum of the extracellular potentials of muscle fiber action potentials of a motor unit. The objective of this preliminary study was to examine possible motor unit mu structural changes in paretic muscle poststroke as a measure by which to assess neural andor biomechanical mechanisms of paresis.
Wavelet analysis of motor unit action potentials c. The composition of ssfaps which best produces the muap is assumed to carry information about the actual distribution of singlefibre action potentials generating the muap. Model based decomposition of muaps into their constituent. However, no study has compared motor unit mu firing and recruitment patterns between children and adults. Intramuscular emg decomposition basing on motor unit.
These were averaged to produce a motor unit action potential template thick, black line in 2second epochs throughout the contraction. The four lower panels show the shimmer plots from a representative trial. A bayes filter detects online the firing motor units by using a dictionary of approximated motor unit action potentials waveforms, and estimates precisely the action potential shapes and the respective firing rates. A procedure for decomposing the myoelectric signal into. This study included spike trigger averaging sta procedures to examine the acceptability of the precision decomposition pd iii derived motor unit action potential muap trains that met the 90% accuracy criteria from the reconstructandtest. In this paper, two schemes for neuromuscular disease classification from electromyography emg signals are proposed based on discrete wavelet transform dwt features. Apart from considering all motor unit action potentials, dominant motor unit action potential is considered for disease classification. Emg evaluation of the motor unit electrophysiologic. The extracellular needle electromyography recording of a motor unit is the motor unit action potential muap. Action potential amplitude as a noninvasive indicator of.
The sta and decomposed ap templates delsys are shown in blue and red, respectively. Therefore, mu action potential amplitudes muapamp and firing rates were examined during two repetitive submaximal contractions. The mus suitable for further analysis were selected using a set of statistical tests that assessed the variability of. The motor unit action potential muap represents the spatial and temporal summation of single fibre extracellular action potentials sfeaps generated from the same motor unit. Neuromuscular disease classification based on discrete. Svmbased validation of motor unit potential trains.
Models of recruitment and rate coding organization in. A technique for the detection, decomposition and analysis. Common drive of motor units in regulation of muscle force. Therefore, we aimed to determine the impact of local muscle cooling on motor unit firing properties using surface emg decomposition. The preferred sites were located between the center and the tendinous areas of the muscle. Individual motor unit action potentials grey lines were spiketriggered from the delsysproduced firing instances. An adaptive algorithm is described that groups motor unit action potentials muaps, detected in a composite emg signal during signal decomposition, and creates partial motor unit action potential. Understanding the normal and abnormal behavior of motor unit control is fundamental to seeking surgical, pharmacological, and exercisebased interventions. In 2016 38th annual international conference of the ieee engineering in medicine and biology society, embc 2016 pp. Multiresolution muaps decomposition and svmbased analysis.
The decomposition reproducibility was evaluated by having two experienced operators independently decompose the same record of empirically obtained myoelectric signal. Home browse by title periodicals computer methods and programs in biomedicine vol. The decomposition algorithm involves separate stages to first identify, match, and update each mus action. Exemplar spiketriggered average sta and decomposed motor unit action potential muap template comparisons. Properties of the motor unit action potential shape in. Impaired motor unit control in paretic muscle post stroke. The representation of the changes generated by a mu is the so called motor unit action potential muap. Emg evaluation of the motor unit electrophysiologic biopsy. Using needle electromyography emg to assess motor unit properties during muscle cooling, is limited and equivocal. It finds an optimal fit of a set of simulated singlefibre action potentials ssfaps to the muap.
Motor unit action potential amplitudes and firing rates. Impaired motor unit control in paretic muscle post stroke assessed using surface electromyography. This report describes an early version of a technique for decomposing surface electromyographic semg signals into the constituent motor unit mu action potential trains. The sum of all this electrical activity is known as a motor unit action potential muap. C the resulting motor unit mu firing patterns for each mu classes identified by the whole decomposition system. Their results were in total agreement for 479 motor unit action potential classifications belonging to five motor unit action potential. A surface sensor array is used to collect four channels of differentially amplified emg signals. Muscular weakness is one of the major impairments limiting motor function following a hemispheric stroke. The train of discharge times predicted from the motoneuron model determined the occurrence of each motor unit action potential. The third section consists of a signal decomposition technique where motor unit action potential trains are extracted from the emg signal using a highly computer assisted interactive algorithm. Electromyogram emg decomposition is the process of breaking down the emg signal into the contributions of its component motor unit action potential muap trains.
Action potential propagation velocities were estimated from an inverse function of contraction time. Motor unit number estimation mune is a technique that uses electromyography to estimate the number of motor units in a muscle principles. Online intramuscular emg decomposition with varying number. When stimulated by an action potential transmitted along the motor neuron, all the fibers in a motor unit. The decomposition is achieved by a set of algorithms that uses a specially developed knowledgebased artificial intelligence.
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