Premovement facilitation of corticospinal excitability before simple and sequential movement

Area of Science:

• Neuroscience
• Motor Control
• Human Movement Science

Background:

• Understanding the neural mechanisms underlying motor preparation is crucial for explaining differences in movement execution.
• Premovement facilitation of corticospinal excitability is a known phenomenon preceding voluntary muscle activation.

Purpose of the Study:

• To investigate if premovement facilitation of corticospinal excitability differs between simple and sequential movements.
• To compare the magnitude and timing of this facilitation in response to different motor tasks.

Main Methods:

• Seven participants performed choice reaction tasks involving either a simple finger press or a sequential finger movement sequence.
• Transcranial magnetic stimulation (TMS) was applied to the motor cortex to measure motor evoked potentials (MEPs) in the first dorsal interosseous muscle.
• MEP amplitude changes were analyzed in relation to the onset of electromyographic activity before movement initiation.

Main Results:

• Motor evoked potential amplitude increased as it approached the electromyographic burst onset for both movement types.
• The premovement facilitation of corticospinal excitability was significantly larger and initiated earlier before sequential movements compared to simple movements.

Conclusions:

• Premovement facilitation of corticospinal excitability exhibits distinct characteristics in magnitude and temporal dynamics between sequential and simple motor tasks.
• These findings suggest differential neural preparation strategies for complex versus basic motor sequences, advancing the understanding of motor planning and execution.