Motor Unit Sampling From Intramuscular Micro-Electrode Array Recordings
Recordings of electrical activity from muscles allow us to identify the activity of pools of spinal motor neurons that send the neural drive for muscle activation. Decoding motor unit and motor neuron activity from muscle recordings can be performed by high-density (HD) electrode systems, both non-i...
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IEEE
2025-01-01
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| Series: | IEEE Transactions on Neural Systems and Rehabilitation Engineering |
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| Online Access: | https://ieeexplore.ieee.org/document/10844937/ |
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| author | Agnese Grison Jaime Ibanez Pereda Dario Farina |
| author_facet | Agnese Grison Jaime Ibanez Pereda Dario Farina |
| author_sort | Agnese Grison |
| collection | DOAJ |
| description | Recordings of electrical activity from muscles allow us to identify the activity of pools of spinal motor neurons that send the neural drive for muscle activation. Decoding motor unit and motor neuron activity from muscle recordings can be performed by high-density (HD) electrode systems, both non-invasively (surface, HD-sEMG) and invasively (intramuscular, HD-iEMG). HD-sEMG recordings are obtained by grids placed on the skin surface while HD-iEMG signals can be acquired by micro-electrode arrays. While it has been shown that HD-iEMG allows the accurate decoding of a larger number of motor units when compared to HD-sEMG, the dependence of motor unit yield on the parameters of the micro-electrode arrays is still unexplored. Here, we used recently developed HD-iEMG electrodes to record from hundreds of recording sites within the muscle. This allowed us to investigate the impact of electrode number, inter-electrode distance, and the number of muscle insertions on the ability to sample motor units within the muscle. Specifically, we recorded both HD-sEMG and HD-iEMG from the Tibialis Anterior muscle of two healthy subjects at various contraction intensities (10%, 30%, and 70% of maximum voluntary contraction, MVC). For the first time, we present intramuscular recordings with more than 140 electrodes inside a single muscle, achieved through multiple implants of high-density micro-electrode arrays. Through systematic offline analyses of these recordings, we tested different electrode configurations to identify optimal setups for accurately capturing motor unit activity. The results revealed that the density of electrodes in the micro-electrode arrays is the most critical factor for maximising the number of identified motor units and ensuring very high accuracy. Comparisons between intramuscular and surface recordings also confirmed that HD-iEMG consistently captures larger and more stable numbers of motor units across subjects and contraction levels. These results underscore the potential of HD-iEMG as a powerful tool for both clinical and research settings, particularly when precise motor unit decomposition is crucial. |
| format | Article |
| id | doaj-art-0a5dcb38e3ea49f1a57ed5885d4e608d |
| institution | Kabale University |
| issn | 1534-4320 1558-0210 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IEEE |
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| series | IEEE Transactions on Neural Systems and Rehabilitation Engineering |
| spelling | doaj-art-0a5dcb38e3ea49f1a57ed5885d4e608d2025-01-31T00:00:08ZengIEEEIEEE Transactions on Neural Systems and Rehabilitation Engineering1534-43201558-02102025-01-013362062910.1109/TNSRE.2025.353105410844937Motor Unit Sampling From Intramuscular Micro-Electrode Array RecordingsAgnese Grison0https://orcid.org/0009-0001-5981-3589Jaime Ibanez Pereda1https://orcid.org/0000-0001-8439-151XDario Farina2https://orcid.org/0000-0002-7883-2697Department of Bioengineering, Imperial College London, London, U.K.Department of Bioengineering, Imperial College London, London, U.K.Department of Bioengineering, Imperial College London, London, U.K.Recordings of electrical activity from muscles allow us to identify the activity of pools of spinal motor neurons that send the neural drive for muscle activation. Decoding motor unit and motor neuron activity from muscle recordings can be performed by high-density (HD) electrode systems, both non-invasively (surface, HD-sEMG) and invasively (intramuscular, HD-iEMG). HD-sEMG recordings are obtained by grids placed on the skin surface while HD-iEMG signals can be acquired by micro-electrode arrays. While it has been shown that HD-iEMG allows the accurate decoding of a larger number of motor units when compared to HD-sEMG, the dependence of motor unit yield on the parameters of the micro-electrode arrays is still unexplored. Here, we used recently developed HD-iEMG electrodes to record from hundreds of recording sites within the muscle. This allowed us to investigate the impact of electrode number, inter-electrode distance, and the number of muscle insertions on the ability to sample motor units within the muscle. Specifically, we recorded both HD-sEMG and HD-iEMG from the Tibialis Anterior muscle of two healthy subjects at various contraction intensities (10%, 30%, and 70% of maximum voluntary contraction, MVC). For the first time, we present intramuscular recordings with more than 140 electrodes inside a single muscle, achieved through multiple implants of high-density micro-electrode arrays. Through systematic offline analyses of these recordings, we tested different electrode configurations to identify optimal setups for accurately capturing motor unit activity. The results revealed that the density of electrodes in the micro-electrode arrays is the most critical factor for maximising the number of identified motor units and ensuring very high accuracy. Comparisons between intramuscular and surface recordings also confirmed that HD-iEMG consistently captures larger and more stable numbers of motor units across subjects and contraction levels. These results underscore the potential of HD-iEMG as a powerful tool for both clinical and research settings, particularly when precise motor unit decomposition is crucial.https://ieeexplore.ieee.org/document/10844937/EMGhigh-densityintramuscularmotor units |
| spellingShingle | Agnese Grison Jaime Ibanez Pereda Dario Farina Motor Unit Sampling From Intramuscular Micro-Electrode Array Recordings IEEE Transactions on Neural Systems and Rehabilitation Engineering EMG high-density intramuscular motor units |
| title | Motor Unit Sampling From Intramuscular Micro-Electrode Array Recordings |
| title_full | Motor Unit Sampling From Intramuscular Micro-Electrode Array Recordings |
| title_fullStr | Motor Unit Sampling From Intramuscular Micro-Electrode Array Recordings |
| title_full_unstemmed | Motor Unit Sampling From Intramuscular Micro-Electrode Array Recordings |
| title_short | Motor Unit Sampling From Intramuscular Micro-Electrode Array Recordings |
| title_sort | motor unit sampling from intramuscular micro electrode array recordings |
| topic | EMG high-density intramuscular motor units |
| url | https://ieeexplore.ieee.org/document/10844937/ |
| work_keys_str_mv | AT agnesegrison motorunitsamplingfromintramuscularmicroelectrodearrayrecordings AT jaimeibanezpereda motorunitsamplingfromintramuscularmicroelectrodearrayrecordings AT dariofarina motorunitsamplingfromintramuscularmicroelectrodearrayrecordings |