Voluntary Motor Command Release Coincides with Restricted Sensorimotor Beta Rhythm Phases.

Area of Science:

• Neuroscience
• Motor Control
• Brain Rhythms

Background:

• Sensory perception and memory are enhanced during specific brain rhythm phases.
• The influence of brain rhythm phase on voluntary movement timing is not well understood.
• Voluntary movement relies on motor commands from the motor cortex (M1) to spinal motoneurons.

Purpose of the Study:

• To investigate whether voluntary movement timing is constrained by sensorimotor brain rhythm phases.
• To test the hypothesis that motor commands are preferentially released from M1 during specific phases of ongoing sensorimotor rhythms.

Main Methods:

• Healthy human participants performed a self-paced finger movement task.
• Electroencephalography (EEG) and electromyography (EMG) were used to record brain and muscle activity.
• Motor command release times were estimated by combining EMG-onset data with measured corticomuscular transmission latencies.

Main Results:

• Motor commands were preferentially released during a specific phase (120-140°) of the contralateral sensorimotor beta rhythm (13-35 Hz).
• Motor command release was uniformly distributed across phases for the contralateral mu rhythm (8-12 Hz) and ipsilateral rhythms.
• This suggests a phase-dependent release of motor commands from the motor cortex.

Conclusions:

• Motor command release is timed to specific phases of the contralateral sensorimotor beta rhythm.
• Sensorimotor beta rhythm phase appears to play a role in sculpting the timing of voluntary human movement.
• These findings extend the understanding of how brain oscillations influence motor control.