Changes in high-frequency neural inputs to muscles during movement cancellation

Area of Science:

• Neuroscience
• Motor Control
• Biomedical Engineering

Background:

• Cortical beta (13-30 Hz) and gamma (30-60 Hz) oscillations are key in motor cortex activity.
• Their transmission to muscles and spinal cord impact is not fully understood, especially during motor control tasks.
• Existing knowledge lacks insight into the saliency of these oscillations at the spinal level.

Purpose of the Study:

• To investigate the modulations in high-frequency inputs to motoneurons during different motor states.
• To examine cortical beta and gamma oscillations in muscle activity during a 'GO'/'NO-GO' task while maintaining stable force.
• To determine if muscle recordings reflect motor states beyond direct force modulation.

Main Methods:

• Utilized a 'GO'/'NO-GO' task with 12 participants performing ballistic contractions or cancellations.
• Recorded brain activity using electroencephalography (EEG) and muscle activity via high-density surface and intramuscular electromyography (EMG).
• Analyzed motor unit (MU) firing activity and spectral content changes in the tibialis anterior muscle during 'NO-GO' trials with stable force.

Main Results:

• Observed increased beta and low-gamma (30-45 Hz) activity in MU population after the 'NO-GO' cue, mirroring EEG findings.
• These spectral changes occurred without significant alterations in muscle force output.
• Demonstrated that muscle activity reflects cortical command changes even when force output is constrained.

Conclusions:

• Motor cortical beta and gamma rhythms are detectable in muscle activity during action cancellation in a 'GO'/'NO-GO' task.
• These muscle-based oscillations occur independently of significant changes in force production.
• Muscle recordings offer insights into motor states not solely related to force control, highlighting potential for peripheral neural interfaces.