Bursting Rate Variability.

Roberto Martin Del Campo Vera,Edmond Jonckheere

doi:10.3389/fphys.2021.724027

Roberto Martin Del Campo Vera, Edmond Jonckheere

Open Access

https://doi.org/10.3389/fphys.2021.724027

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Abstract

In this paper, a new electromyographic phenomenon, referred to as Bursting Rate Variability (BRV), is reported. Not only does it manifest itself visually as a train of short periods of accrued surface electromyographic (sEMG) activity in the traces, but it has a deeper underpinning because the sEMG bursts are synchronous with wavelet packets in the D8 subband of the Daubechies 3 (db3) wavelet decomposition of the raw signal referred to as “D8 doublets”—which are absent during muscle relaxation. Moreover, the db3 wavelet decomposition reconstructs the entire sEMG bursts with two contiguous relatively high detail coefficients at level 8, suggesting a high incidence of two consecutive neuronal discharges. Most importantly, the timing between successive bursts shows some variability, hence the BRV acronym. Contrary to Heart Rate Variability (HRV), where the R-wave is easily identified, here, time-localization of the burst requires a statistical waveform matching between the “D8 doublet” and the burst in the raw sEMG signal. Furthermore, statistical fitting of the empirical distribution of return times shows a striking difference between control and quadriplegic subjects. Finally, the BRV rate appears to be within 60–88 bursts per minute on average among 9 human subjects, suggesting a possible connection between BRV and HRV.

Highlights

The surface electromyographic activity recorded along the paraspinal muscles of human subjects shows some standing wave properties, even though the trunk does not manifest a visually obvious movement (Jonckheere et al, 2010; Martin del Campo and Jonckheere, 2016)
The quadriplegic subjects consistently presented the Weibull distribution as the best fit, and mixtures of normal distributions in the case of control subjects; this discrepancy already points to some neurophysiological applications of Bursting Rate Variability (BRV)
The major contribution in this paper is the identification of a new neurophysiological phenomenon—the Bursting Rate Variability that bears some resemblance to Heart Rate Variability, but that still differs from it in several respects, mainly single vs. double discharge

Summary

Introduction

The surface electromyographic (sEMG) activity recorded along the paraspinal muscles of human subjects shows some standing wave properties, even though the trunk does not manifest a visually obvious movement (Jonckheere et al, 2010; Martin del Campo and Jonckheere, 2016). Such conditions can be reproduced by putting the research subject in the prone position and applying light pressure at some specific “gateway” points of the spine (usually the neck and the coccyx) to elicit the oscillation. A further confirmation of the CPG hypothesis is that two quadriplegic subjects have been able to sustain the so-called spinal wave (Jonckheere and Lohsoonthorn, 2004; Jonckheere et al, 2010; Musuvathy and Jonckheere, 2010).

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