A mathematical analysis of SFAP convolutional models

Rodriguez‐Falces, Javier; Trigueros, A.M.; Useros, L.G.; Carreño, Ignacio Rodríguez; Irujo, Javier Navallas

doi:10.1109/tbme.2005.845045

Cited by 9 publications

(4 citation statements)

References 13 publications

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“…More specifically, the non-propagating component can be seen to arise from a stationary source located at a fixed location, the fiber-tendon junction. Therefore, positional changes of this junction relative to the recording electrode alter the magnitude of the whole end-of-fiber component [ 13 ]. Conversely, the propagating component results from the propagation of the action potential along the muscle fiber.…”

Section: Discussionmentioning

confidence: 99%

Effects of muscle shortening on single-fiber, motor unit, and compound muscle action potentials

Rodriguez‐Falces

Malanda

Navallas

2021

Med Biol Eng Comput

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Even under isometric conditions, muscle contractions are associated with some degree of fiber shortening. The effects of muscle shortening on extracellular electromyographic potentials have not been characterized in detail. Moreover, the anatomical, biophysical, and detection factors influencing the muscle-shortening effects have been neither identified nor understood completely. Herein, we investigated the effects of muscle shortening on the amplitude and duration characteristics of single-fiber, motor unit, and compound muscle action potentials. We found that, at the single-fiber level, two main factors influenced the muscle-shortening effects: (1) the electrode position and distance relative to the myotendinous zone and (2) the electrode distance to the maxima of the dipole field arising from the stationary dipole created at the fiber-tendon junction. Besides, at the motor unit and muscle level, two additional factors were involved: (3) the overlapping between the propagating component of some fibers with the non-propagating component of other fibers and (4) the spatial spreading of the fiber-tendon junctions. The muscle-shortening effects depend critically on the electrode longitudinal distance to the myotendinous zone. When the electrode was placed far from the myotendinous zone, muscle shortening resulted in an enlargement and narrowing of the final (negative) phase of the potential, and this enlargement became less pronounced as the electrode approached the fiber endings. For electrode locations close to the myotendinous zone, muscle shortening caused a depression of both the main (positive) and final (negative) phases of the potential. Beyond the myotendinous zone, muscle shortening led to a decrease of the final (positive) phase. The present results provide reference information that will help to identify changes in MUPs and M waves due to muscle shortening, and thus to differentiate these changes from those caused by muscle fatigue. Graphical abstract

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Section: Discussionmentioning

confidence: 99%

Effects of muscle shortening on single-fiber, motor unit, and compound muscle action potentials

Rodriguez‐Falces

Malanda

Navallas

2021

Med Biol Eng Comput

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“…Discrepancies in the extent of potentiation between Ampli-FIRST and Ampli SECOND might be related to the fact that the M-wave first phase results from the propagation of the excitation source along the fiber, whereas the second phase mainly reflects the extinction of this source at the aponeurosis/tendon (15). Therefore, if changes in muscle architecture had persisted for a few seconds after the contraction, these changes would have influenced the M-wave second phase to a greater degree compared with the first phase (35,37).…”

Section: Discussionmentioning

confidence: 99%

M-wave potentiation after voluntary contractions of different durations and intensities in the tibialis anterior

Rodriguez‐Falces

Duchateau

Muraoka

et al. 2015

Journal of Applied Physiology

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The study was undertaken to provide insight into the mechanisms underlying the potentiation of the muscle compound action potential (M wave) after conditioning contractions. M waves were evoked in the tibialis anterior before and after isometric maximal voluntary contractions (MVC) of 1, 3, 6, 10, 30, and 60 s, and after 3-s contractions at 10, 30, 50, 70, 90, and 100% MVC. The amplitude, duration, and area of the first and second phases of the M wave, together with the median frequency (Fmedian) and muscle fiber conduction velocity (MFCV) were recorded. Furthermore, twitch force, muscle fascicle length, and pennation angle were measured at rest, before, and 1 s after the conditioning contractions. The results indicate that only the amplitude of the second phase of the M wave was significantly increased after conditioning contractions. The extent of this potentiation was similar for MVC durations ranging from 1 to 10 s and augmented progressively with contraction intensity from 30 to 70% MVC. After these conditioning contractions, the duration and area of the two M-wave phases decreased (P< 0.05), whereas MFCV and Fmedian increased (P < 0.05). For all of these parameters, the greatest changes occurred 1 s after the conditioning contraction. Changes in MFCV after the contractions were correlated with those in M-wave second-phase amplitude (r(2) = 0.42; P < 0.05) and Fmedian (r(2) = 0.53; P < 0.05). In contrast, fascicle length and pennation angle did not change after the conditioning contractions. It is concluded that the potentiation of the second phase of the M wave is mainly due to an increased MFCV.

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“…Furthermore, the signal characteristics at the wrist are different than that at the belly of the muscle. The electric potentials recorded at the wrist are end-of-fiber components (25), which are non-propagating potentials highly synchronized across channels (as shown in Fig. 2d) and shorter in time than the propagating signals recorded from muscles (43).…”

Section: Discussionmentioning

confidence: 92%

“…Each motoneuron discharge generates an electric field transmitted through the tendon tissue that can be distinguished from the fields generated by other motoneurons. The biophysical properties of electric potentials recorded over tendon tissues are known (25)(26)(27)(28), but these signals have not previously been used to identify individual motoneuron discharges. Here we propose an innovative interface that decodes spinal motoneuron discharges from tendon electric signals at the wrist to develop a non-invasive, unobtrusive, and socially acceptable wearable.…”

Section: Introductionmentioning

confidence: 99%

Non-invasive real-time access to the output of the spinal cord via a wrist wearable interface

Guerra

Barsakcioglu²,

Vujaklija³

et al. 2021

Preprint

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Despite the promising features of neural interfaces, their trade-off between information transfer and invasiveness has limited translation and viability outside research settings. Here, we present a non-invasive neural interface that provides access to spinal motoneuron activities from a sensor band at the wrist. The interface decodes electric signals present at the tendon endings of the forearm muscles by using a model of signal generation and deconvolution. First, we evaluated the reliability of the interface to detect motoneuron firings, and thereafter we used the decoded neural activity for the prediction of finger movements in offline and real-time conditions. The results showed that motoneuron activity decoded from the wrist accurately predicted individual and combined finger commands and therefore allowed for highly accurate real-time control. These findings demonstrate the feasibility of a wearable, non-invasive, neural interface at the wrist for precise real-time control based on the output of the spinal cord.

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A mathematical analysis of SFAP convolutional models

Cited by 9 publications

References 13 publications

Effects of muscle shortening on single-fiber, motor unit, and compound muscle action potentials

Effects of muscle shortening on single-fiber, motor unit, and compound muscle action potentials

M-wave potentiation after voluntary contractions of different durations and intensities in the tibialis anterior

Non-invasive real-time access to the output of the spinal cord via a wrist wearable interface

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