Cortical potentials associated with voluntary biting movement in humans.

Area of Science:

• Neuroscience
• Motor Control
• Electrophysiology

Background:

• Bereitschaftspotentials (BPs) are slow negative electrical potentials recorded over the scalp.
• BPs precede voluntary movements and are associated with motor preparation.
• The precise cortical origins and hemispheric control of specific movements like jaw biting remain under investigation.

Purpose of the Study:

• To investigate the distribution of Bereitschaftspotentials (BPs) preceding unilateral jaw biting movements.
• To determine the relationship between specific cortical regions and masseter muscle activation.
• To identify the hemispheric dominance in controlling unilateral jaw biting.

Main Methods:

• Recording of scalp electroencephalography (EEG) from midline-central, central, and temporal areas using the international 10-20 system in 10 healthy subjects.
• Measurement of BPs and a negative slope component (NS) relative to the electromyographic (EMG) onset of the masseter muscle during self-paced unilateral biting.
• Analysis of BP and NS amplitudes and occurrence rates in different scalp regions.

Main Results:

• Cortical negative potentials (BPs) were detected preceding masseter EMG onset by 1.0–1.5 seconds.
• A negative slope component (NS) was observed 70–80 ms before masseter EMG onset, primarily in bilateral temporal areas.
• BP and NS amplitudes were largest in the temporal areas (T3 and T4) ipsilateral to the biting side.
• The NS occurred more frequently in ipsilateral temporal areas (80% at T3, 60% at T4).

Conclusions:

• Unilateral jaw biting movements appear to be primarily controlled by the ipsilateral cerebral hemisphere.
• The temporal scalp areas, particularly those ipsilateral to the biting side, show significant involvement in the preparation and execution of unilateral jaw biting.
• The findings contribute to understanding the neural control mechanisms underlying complex orofacial motor tasks.