Oscillatory interaction between human motor cortex and trunk muscles during isometric contraction

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• The motor cortex controls voluntary movements, including those of the limbs and trunk.
• Oscillatory interactions between brain and muscle activity are crucial for motor control.

Purpose of the Study:

• To investigate the oscillatory interaction between human motor cortex magnetoencephalography (MEG) signals and electromyogram (EMG) from paraspinal (PS) and abdominal (ABD) trunk muscles.
• To compare these interactions with those observed during limb muscle (first dorsal interosseus - FDI, tibialis anterior - TA) contractions.

Main Methods:

• Magnetoencephalography (MEG) was used to record human motor cortex activity.
• Surface electromyogram (EMG) was recorded from paraspinal (PS), abdominal (ABD), first dorsal interosseus (FDI), and tibialis anterior (TA) muscles.
• Coherence analysis was performed in the 15-35 Hz frequency band to assess oscillatory interactions.

Main Results:

• Significant 15-35 Hz coherence was found between the motor cortex and both PS and ABD muscles, though weaker than for FDI and TA.
• Cortical sources for PS and ABD coherence were located in the motor cortex, consistent with the trunk area of the motor homunculus.
• PS muscle coherence originated from contralateral cortical sources, while ABD muscle coherence involved bilateral sources.

Conclusions:

• Descending motor commands for both limb and trunk muscles are modulated by cortical oscillations during isometric contractions.
• This modulation is weaker and may be bilateral for trunk muscles compared to limb muscles.