Coherent oscillations in monkey motor cortex and hand muscle EMG show task-dependent modulation

Area of Science:

• Neuroscience
• Motor Control
• Systems Neuroscience

Background:

• Understanding the neural mechanisms underlying motor control is crucial for addressing movement disorders.
• The primary motor cortex plays a key role in planning and executing voluntary movements.
• Investigating neural oscillations provides insights into the coordinated activity of neuronal populations.

Purpose of the Study:

• To investigate the presence and characteristics of neural oscillations in the primary motor cortex during a precision grip task.
• To determine if these oscillations are coherent between different cortical sites and muscle activity.
• To explore the relationship between these oscillations and the output of pyramidal tract neurons.

Main Methods:

• Local field potentials (slow waves) and pyramidal tract neuron (PTN) discharge were recorded in macaque monkeys performing a precision grip task.
• Spectral analysis was used to identify and quantify oscillations and coherence between cortical sites and electromyography (EMG) signals.
• Spike-triggered averages were computed to examine the relationship between PTN activity and slow wave oscillations.

Main Results:

• 20-30 Hz oscillations were observed in the motor cortex and were coherent between spatially separated recording sites.
• Coherence was also found between cortical oscillations and muscle activity (EMG) during the task.
• These oscillations were predominantly present during the hold phase of the precision grip and were associated with PTN discharge.

Conclusions:

• The study demonstrates the presence of task-dependent 20-30 Hz oscillations in the monkey motor cortex.
• These oscillations are coherent across cortical areas and are linked to muscle activity and pyramidal tract output.
• The findings suggest that these neural rhythms play a role in the coordinated control of precision grip movements.