A Novel Scalp Acupuncture-based Method to Target the Hand Motor Hotspot for Non-invasive Brain Stimulation.

Area of Science:

• Neuroscience
• Neuromodulation
• Motor Cortex Mapping

Background:

• Precise primary motor cortex (M1) localization is crucial for effective neuromodulation.
• The standard C3 site may not be optimal for targeting hand muscles.
• Advanced neuroimaging tools like navigated transcranial magnetic stimulation (nTMS) are not always accessible.

Purpose of the Study:

• To propose and validate a novel neuroanatomy-based method for identifying the M1 hotspot for hand muscles.
• To compare the effectiveness of the proposed method against the conventional C3 site.

Main Methods:

• A step-by-step protocol using an acupuncture-based approach was developed to identify the M1 hotspot for the flexor digitorum superficialis (FDS) muscle.
• Motor evoked potentials (MEPs) were evaluated at both the identified hotspot and the C3 site before and after neuromodulation.

Main Results:

• The proposed M1 hotspot demonstrated significantly higher baseline MEP amplitudes compared to the C3 site.
• Higher MEP amplitudes were also observed at the proposed hotspot following neuromodulation.
• The neuroanatomy-based method proved effective in localizing the M1 hotspot for the FDS muscle.

Conclusions:

• The proposed acupuncture-based approach provides a validated and practical method for M1 hotspot localization for the FDS muscle.
• This technique can enhance neuromodulation efficacy in clinical settings lacking advanced neuroimaging.
• The study highlights the limitations of the C3 site for specific muscle targeting.