Effects of Transcranial Direct Current Stimulation over the Left Sensorimotor Cortex on Bimanual Force Control: A...

Area of Science:

• Neuroscience
• Motor Control
• Human Performance

Background:

• Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique.
• The precise mechanisms by which tDCS modulates motor performance, particularly in bimanual tasks, require further elucidation.
• Motor-premotor regions are critical for planning and executing movements.

Purpose of the Study:

• To investigate the effects of anodal tDCS on bimanual isometric force control.
• To explore the underlying mechanisms, specifically the role of proprioceptive feedback processing.
• To assess changes in force accuracy, error, and oscillatory activity during a force-matching task.

Main Methods:

• Twenty-four athletes received either anodal tDCS or sham stimulation over the left sensorimotor cortex.
• Participants performed a bimanual isometric force-matching task with and without visual feedback.
• Analysis included force undershoot, root mean square error (RMSE), spectral power (1-3 Hz), and inter-hand coherence.
• A computational model was used to simulate the effects of altered proprioceptive feedback gain.

Main Results:

• Anodal tDCS significantly reduced force undershoot and improved RMSE, indicating enhanced force control.
• Spectral power in the 1-3 Hz band increased, suggesting augmented corrective oscillations.
• These improvements were observed within the tDCS group, while the sham group showed no significant changes.
• Computational modeling supported the hypothesis that enhanced proprioceptive feedback gain underlies the observed behavioral improvements.

Conclusions:

• Anodal tDCS over the left sensorimotor/premotor region can enhance bimanual force control, especially when proprioceptive feedback is crucial.
• The findings suggest that tDCS may modulate motor performance by improving sensory feedback processing.
• Larger sample sizes are recommended for future studies to confirm between-group specificity and enhance statistical power.