Involvement of the sensorimotor cortex in physiological force and action tremor

Area of Science:

• Neuroscience
• Motor Control
• Biophysics

Background:

• The sensorimotor cortex plays a crucial role in voluntary movement and postural control.
• Understanding the neural mechanisms underlying physiological tremor is essential for diagnosing and treating movement disorders.

Purpose of the Study:

• To investigate the differential involvement of the sensorimotor cortex in physiological force tremor versus action tremor during wrist movements.
• To explore the relationship between magnetoencephalography (MEG) signals and electromyogram (EMG) activity in the motor cortex.

Main Methods:

• Whole-scalp magnetoencephalography (MEG) and surface electromyogram (EMG) of forearm extensor muscles were recorded simultaneously in 10 healthy subjects.
• Subjects performed isometric wrist contractions and phasic wrist movements.
• Coherence and time-domain analyses were used to assess the correspondence between MEG and EMG signals.

Main Results:

• A significant correspondence was found between MEG signals (originating from the motor cortex hand region) and 6-12 Hz EMG activity during isometric postural contractions in 8 out of 10 subjects.
• Little evidence of correspondence was observed between contralateral EMG and MEG signals over the Rolandic region during phasic movements.

Conclusions:

• The sensorimotor cortex exhibits differential involvement in the generation of physiological force tremor and action tremor at the wrist.
• MEG and EMG can differentiate neural activity related to postural control versus voluntary movement execution.