High-resolution head model of transcranial direct current stimulation: A labeling analysis

Area of Science:

• Neuroscience
• Biomedical Engineering
• Computational Modeling

Background:

• Transcranial direct current stimulation (tDCS) is used in research and clinics for its lasting modulatory effects.
• Computational models have advanced understanding of tDCS-induced electric fields but often lack detailed quantification across brain subcomponents.
• Understanding regional current distribution is crucial for interpreting tDCS outcomes and optimizing stimulation.

Purpose of the Study:

• To quantify and compare electric field and current density induced by conventional and High Definition (HD)-tDCS.
• To utilize a high-resolution head model with detailed brain parcellation (17 gyri, 10 sub-cortical regions).
• To investigate the spatial and depth-wise distribution of electrical fields across different brain structures for both tDCS montages.

Main Methods:

• Development and application of a high-resolution computational head model.
• Parcellation of the brain into 17 gyri and 10 sub-cortical regions.
• Simulation of current flow and electric field induction for conventional and HD-tDCS electrode montages.
• Comparative analysis of induced electrical fields across brain regions for each montage.

Main Results:

• Maximum electric field was observed in the precentral gyrus for both conventional and HD-tDCS montages.
• HD-tDCS demonstrated spatially restricted and shallower current flow compared to conventional tDCS.
• Conventional tDCS led to sub-cortical current densities ranging from 47-95% of upper cortical regions, while HD-tDCS reduced this to 12-32%.

Conclusions:

• HD-tDCS offers more focal stimulation with significantly reduced current penetration into sub-cortical structures compared to conventional tDCS.
• Detailed computational models incorporating labeled brain regions are valuable for optimizing tDCS electrode design and stimulation parameters.
• This systematic quantification aids in understanding the functional relevance of regional current distribution in tDCS studies.