Electroacupuncture modulates cortical excitability in a manner dependent on the parameters used

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Neuromodulation

Background:

• Electroacupuncture (EA) is known to modulate brain activity.
• Its specific effects on corticospinal excitability of the primary motor cortex (M1) remain largely unexplored.

Purpose of the Study:

• To investigate how different electroacupuncture (EA) parameters influence M1 excitability in healthy individuals.
• To determine the optimal EA frequency and amplitude for modulating M1 excitability.

Main Methods:

• A double-blind, randomized controlled trial was conducted on healthy subjects.
• Participants received EA at the LI4 acupoint with varying frequencies (10 or 100 Hz) and amplitudes (sensory or motor threshold).
• Transcranial magnetic stimulation (TMS) and electromyography (EMG) were used to measure M1 excitability before and after EA.

Main Results:

• EA at 100 Hz and sensory threshold significantly increased M1 corticospinal excitability compared to the control group.
• No significant changes in M1 excitability were observed with other EA parameter combinations.
• Specific measures like resting motor threshold, motor evoked potential, short intracortical inhibition, and intracortical facilitation were analyzed.

Conclusions:

• Electroacupuncture (EA) at a 100 Hz frequency and sensory threshold intensity enhances M1 corticospinal excitability.
• This observed increase in excitability may be linked to a reduction in the activity of intracortical inhibitory mechanisms.