Transcranial current stimulation focality using disc and ring electrode configurations: FEM analysis

Area of Science:

• Neuroscience
• Biophysics
• Computational Modeling

Background:

• Transcranial current stimulation (TCS) is a non-invasive brain stimulation technique.
• Optimizing electrode configurations is crucial for targeted neuromodulation.
• Current TCS protocols often use diffuse electric field patterns.

Purpose of the Study:

• To compare the focality and electric field characteristics of various TCS electrode configurations.
• To identify optimal electrode designs for targeted cortical stimulation.
• To evaluate electric field polarity and magnitude for different neural targets.

Main Methods:

• Finite-element concentric spheres human head model used for simulations.
• Simulated six electrode configurations: distant-bipolar, adjacent-bipolar, tripolar, belt, concentric ring, and double concentric ring.
• Analyzed electric field focality for radial, tangential, and magnitude components at the cortical surface.

Main Results:

• Distant-bipolar configuration produced diffuse, bi-directional radial modulation.
• Adjacent-bipolar and tripolar configurations improved focality but increased surface current or reduced radial bi-directionality.
• Concentric ring configuration yielded the highest spatial focality and uni-directional radial modulation, despite higher total surface current.

Conclusions:

• Concentric ring electrode designs offer superior focality for transcranial current stimulation.
• This configuration allows for targeted modulation of superficial cortical neurons.
• Adjusting ring dimensions or using double concentric rings can balance focality and surface current.