Corticomuscular coherence existed at the single motor unit level.

Area of Science:

• Neuroscience
• Motor Control
• Biomedical Engineering

Background:

• Monosynaptic cortico-motoneuronal connections imply independent motor unit (MU) commands from the motor cortex.
• Previous corticomuscular coherence (CMC) studies using EEG and EMG did not explore corticospinal function at the single MU level.

Purpose of the Study:

• To investigate synchronous activity between the motor cortex and individual MUs.
• To determine if cortico-motoneuronal coherence (CMnC) exists at the single MU level.

Main Methods:

• Calculated corticomuscular coherence (CMC) between electroencephalogram (EEG) and motor unit (MU) firing event trains.
• Extracted MU firing event trains using electromyogram (EMG) decomposition techniques.

Main Results:

• Significant cortico-motoneuronal coherence (CMnC) was observed between the motor cortex and some individual MUs.
• CMnC occurred across theta, alpha, beta, and gamma EEG frequency bands, unlike conventional CMC.
• Coherent MUs (CohMU) were identified even when EMG signals were not coupled with cortical activities.

Conclusions:

• Corticomuscular coherence exists at the single motor unit level, providing a novel perspective on corticomuscular coupling.
• CMnC offers a potential method to investigate complex cortical-muscular interactions by separating correlated components.
• Further research into CMnC can enhance understanding of the neural control of movement.