Search bioRxiv⌕ Search

Biology subjects

Senay, B.

Publications and source records attributed to Senay, B..

2 recordsLinked to original sources
bioRxiv2026

Motor Unit Number Estimation in Magnetomyography

ObjectiveInvestigation of the feasibility and characteristics of contactless motor unit number estimation (MUNE) using optically pumped magnetometer-based magnetomyography (OPM-MMG) as compared to surface electromyography (EMG). MethodsSimultaneous electrically evoked OPM-MMG and EMG signals of the abductor digiti minimi muscle (ADM) were measured in three healthy participants. To characterize MUNE across both modalities and account for within-subject physiological variability, 20 repetitions of electrical stimulation of the ulnar nerve at randomized intensities ranging from 5 to 30 mA in 0.1 mA increments were performed, resulting in a total of 5,020 evoked responses per subject. We quantitatively compared of MUNE and evoked EMG/MMG signal characteristics, including signal-to-noise ratio (SNR) and motor unit response amplitudes. SNR was equalized between measurement modalities to estimate the effect of SNR on MUNE. ResultsMMG-derived MUNE (mMUNE) could be assessed contactlessly. mMUNE estimates were on average 40% lower than EMG-derived MUNE (eMUNE), ranging from 30-65 for mMUNE versus 69-101 for eMUNE. Equalizing the EMG SNR (29-31 dB) to match the MMG SNR (18-27 dB) yielded comparable eMUNE and mMUNE estimates. Peak-to-peak amplitudes of the supramaximal compound motor unit fields ranged from 34-73 pT and single motor unit fields ranged from 0.7-1.4 pT. SignificanceThese findings demonstrate that OPM-MMG enables contactless motor unit number estimation.

neuroscience↗
bioRxiv2026

Reliability of Spatiotemporal Neuromuscular Activity Patterns in Magnetomyography Across Force Levels

BackgroundMagnetomyography (MMG) using an optically pumped magnetometer (OPM) provides a contactless and non-invasive approach to assess neuromuscular activity. However, given the limited studies using optically pumped magnetometer magnetomyography (OPM-MMG) and that those primarily used a single OPM, it remains to be characterized how stable individual neuromuscular activity patterns are over time and across different force levels when using multiple OPMs, specifically an array-based MMG. Methods12 healthy subjects performed ramped isometric contractions at 10, 20, 40, 60, and 80% maximal voluntary contraction (MVC), while a 2x3 OPM array recorded MMG signals from the tibialis anterior (TA). For the test-retest reliability, ramps at 20% and 60% MVC were each repeated once. For each subject, Spearmans rank correlation was computed across all OPM sensors between force conditions to assess consistency of feature rankings, and within-subject spatial repeatability between repeated 20% and 60% MVC ramps was quantified using ICC (3,1) (two-way mixed-effects, single-measure, absolute agreement). ResultsIn 9 of 12 subjects, Spearmans rank analyses showed generally high correlations across force levels ({rho} = 0.37 to 0.91, p<0.05), whereas in the remaining 3 subjects, spatial patterns were less stable ({rho} = -0.73 to 0.58, p<0.05). ICC (3,1) between repeated ramps indicated high within-subject spatial repeatability of the array pattern in 9 out of 12 subjects, with ICC > 0.75 at 20% MVC (5 out of 9 subjects) and 60% MVC (6 out of 9 subjects), respectively. In contrast, the remaining 3 subjects showed lower ICCs (20% MVC: -0.28 to 0.51; 60% MVC: 0.22 to 0.80). ConclusionArray-based OPM-MMG shows high within-subject stability of spatial patterns across force levels and strong test-retest repeatability in the majority of subjects (9 out of 12), supporting its use for characterizing force-dependent neuromuscular activity while acknowledging inter-subject variability.

neuroscience↗