scholarly journals An adjoint approach to identification in Electromyography: Modeling and first order optimality conditions

2021 ◽  
Author(s):  
Tobias Sproll ◽  
Anton Schiela
Keyword(s):  
Optimality Conditions ◽  
Motor Units ◽  
Surface Emg ◽  
Control Approach ◽  
First Order ◽  
Single Motor Units ◽  
Density Surface ◽  
Adjoint Approach ◽  
Optimal Control Approach ◽  
First Order Optimality Conditions

Abstract In medical treatment, it can be necessary to know the position of a motor unit in a muscle. Recent advances in high-density surface Electromyography (EMG) measurement have opened the possibility of extracting information about single motor units. We present a mathematical approach to identify these motor units. On the base of an electrostatic forward model, we introduce an adjoint approach to efficiently simulate a surface EMG measurement and an optimal control approach to identify these motor units. We show basic results on existence of solutions and first-order optimality conditions.

Excitability tests using high-density surface-EMG: A novel approach to studying single motor units

2018 ◽  
Vol 129 (8) ◽  
pp. 1634-1641 ◽  
Author(s):  
Boudewijn T.H.M. Sleutjes ◽  
Judith Drenthen ◽  
Ernest Boskovic ◽  
Leonard J. van Schelven ◽  
Maria O. Kovalchuk ◽  
...  
Keyword(s):  
Motor Units ◽  
Surface Emg ◽  
High Density ◽  
Single Motor ◽  
Single Motor Units ◽  
Novel Approach ◽  
Density Surface

Rectification is required to extract oscillatory envelope modulation from surface electromyographic signals

2014 ◽  
Vol 112 (7) ◽  
pp. 1685-1691 ◽  
Author(s):  
Christopher J. Dakin ◽  
Brian H. Dalton ◽  
Billy L. Luu ◽  
Jean-Sébastien Blouin
Keyword(s):  
Motor Unit ◽  
Stimulus Frequency ◽  
Motor Units ◽  
Surface Emg ◽  
Medial Gastrocnemius ◽  
Single Motor Unit ◽  
Single Motor ◽  
Single Motor Units ◽  
Emg Signal ◽  
Envelope Modulation

Rectification of surface electromyographic (EMG) recordings prior to their correlation with other signals is a widely used form of preprocessing. Recently this practice has come into question, elevating the subject of EMG rectification to a topic of much debate. Proponents for rectifying suggest it accentuates the EMG spike timing information, whereas opponents indicate it is unnecessary and its nonlinear distortion of data is potentially destructive. Here we examine the necessity of rectification on the extraction of muscle responses, but for the first time using a known oscillatory input to the muscle in the form of electrical vestibular stimulation. Participants were exposed to sinusoidal vestibular stimuli while surface and intramuscular EMG were recorded from the left medial gastrocnemius. We compared the unrectified and rectified surface EMG to single motor units to determine which method best identified stimulus-EMG coherence and phase at the single-motor unit level. Surface EMG modulation at the stimulus frequency was obvious in the unrectified surface EMG. However, this modulation was not identified by the fast Fourier transform, and therefore stimulus coherence with the unrectified EMG signal failed to capture this covariance. Both the rectified surface EMG and single motor units displayed significant coherence over the entire stimulus bandwidth (1–20 Hz). Furthermore, the stimulus-phase relationship for the rectified EMG and motor units shared a moderate correlation ( r = 0.56). These data indicate that rectification of surface EMG is a necessary step to extract EMG envelope modulation due to motor unit entrainment to a known stimulus.

scholarly journals Three-Dimensional Innervation Zone Imaging from Multi-Channel Surface EMG Recordings

2015 ◽  
Vol 25 (06) ◽  
pp. 1550024 ◽  
Author(s):  
Yang Liu ◽  
Yong Ning ◽  
Sheng Li ◽  
Ping Zhou ◽  
William Z. Rymer ◽  
...  
Keyword(s):  
High Performance ◽  
Unmet Need ◽  
Three Dimensional ◽  
Motor Units ◽  
Decomposition Methods ◽  
Surface Emg ◽  
Source Imaging ◽  
Dynamic Propagation ◽  
Channel Surface ◽  
Density Surface

There is an unmet need to accurately identify the locations of innervation zones (IZs) of spastic muscles, so as to guide botulinum toxin (BTX) injections for the best clinical outcome. A novel 3D IZ imaging (3DIZI) approach was developed by combining the bioelectrical source imaging and surface electromyogram (EMG) decomposition methods to image the 3D distribution of IZs in the target muscles. Surface IZ locations of motor units (MUs), identified from the bipolar map of their MU action potentials (MUAPs) were employed as a prior knowledge in the 3DIZI approach to improve its imaging accuracy. The performance of the 3DIZI approach was first optimized and evaluated via a series of designed computer simulations, and then validated with the intramuscular EMG data, together with simultaneously recorded 128-channel surface EMG data from the biceps of two subjects. Both simulation and experimental validation results demonstrate the high performance of the 3DIZI approach in accurately reconstructing the distributions of IZs and the dynamic propagation of internal muscle activities in the biceps from high-density surface EMG recordings.

scholarly journals Nonlinear summation of contractions in cat muscles. I. Early depression.

1981 ◽  
Vol 78 (3) ◽  
pp. 277-293 ◽  
Author(s):  
R B Stein ◽  
F Parmiggiani
Keyword(s):  
Motor Units ◽  
Repetitive Stimulation ◽  
Actin Binding ◽  
Linear Summation ◽  
First Order ◽  
Twitch Response ◽  
Single Motor Units ◽  
Sodium Hydrate ◽  
Slow Twitch ◽  
Stimulation Of

Nerves to fast- and slow-twitch cat muscles were stimulated with various numbers of supramaximal pulses under isometric conditions. By subtracting the force produced by j - 1 pulses from that produced by j pulses, the contribution of the j th pulse could be compared with the response to one pulse (twitch response). A less-than-linear summation (depression) was observed during the rising phase of the twitch. This depression became increasingly prominent and longer in duration with repetitive stimulation. A more-than-linear summation (facilitation) was observed during the falling phase of the twitch, which became increasingly delayed and smaller in amplitude with repetitive stimulation. The early depression could be abolished for the first few pulses by Dantrolene [1-(5-p-nitrophenyl) furfurilidene amino hydantoin sodium hydrate], which reduced Ca++ release from the sarcoplasmic reticulum. The depression was less prominent at short muscle lengths or with stimulation of single motor units. A first-order, saturable reaction such as Ca++ binding to troponin or actin binding to myosin can quantitatively account for the early depression.

Discharge Variability of Motor Units in an Intrinsic Muscle of Transplanted Hand

2008 ◽  
Vol 99 (5) ◽  
pp. 2232-2240 ◽  
Author(s):  
Dario Farina ◽  
Marco Pozzo ◽  
Marco Lanzetta ◽  
Roger M. Enoka
Keyword(s):  
Motor Neurons ◽  
Action Potentials ◽  
Discharge Rate ◽  
Motor Units ◽  
Surface Emg ◽  
Intrinsic Muscle ◽  
Single Motor Units ◽  
Abductor Digiti Minimi ◽  
The Individual ◽  
Ramp Contractions

The study analyzed the discharge characteristics of the motor units in an intrinsic muscle of a transplanted hand. Multichannel electromyographic (EMG) recordings were obtained in 11 experimental sessions over 16 mo starting from day 205 after a hand was transplanted in a 35-yr-old man who had lost his right hand 22 yr earlier. The action potentials discharged by single motor units were identified from the surface EMG signals of the abductor digiti minimi muscle in the transplanted hand as the individual performed 60-s maximal and linearly increasing (ramp) contractions. Discharge rate decreased from 27.1 ± 8.4 pulses per second (pps) at the start of the maximal contractions to 17.2 ± 2.9 pps at the end ( P < 0.001) and increased from 17.4 ± 4.3 to 22.1 ± 5.0 pps during the ramp contractions ( P < 0.05). The SD of the interspike interval (ISI) nearly related to the mean ISI with a similar regression slope for the maximal (0.49 ± 0.09) and ramp contractions (0.43 ± 0.10). The coefficient of variation for ISI was higher than values in able-bodied persons and did not change during either the maximal (36.8 ± 10.8%) or the ramp contractions (35.9 ± 7.4%). High-frequency bursts of activity with <20 ms between two and six action potentials occurred during both maximal and ramp contractions. In conclusion, motor neurons that reinnervated a muscle in a transplanted hand discharged action potentials with a high degree of variability that suggested greater synaptic noise during the voluntary contractions.

scholarly journals First-order optimality conditions for convex semi-infinite min-max programming with noncompact sets

2009 ◽  
Vol 5 (4) ◽  
pp. 851-866 ◽  
Author(s):  
Jinchuan Zhou ◽  
◽  
Changyu Wang ◽  
Naihua Xiu ◽  
Soonyi Wu ◽  
...  
Keyword(s):  
Optimality Conditions ◽  
First Order ◽  
First Order Optimality Conditions
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