Predicted current densities in the brain during transcranial electrical stimulation.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Computational Modeling

Background:

• Transcranial electrical stimulation (TES) effectiveness depends on accurate current distribution prediction.
• Finite element method (FEM) offers a potential approach for modeling complex biological systems like the human brain.

Purpose of the Study:

• To evaluate the application of FEM for predicting current pathways and intensities in the brain during TES.
• To investigate the impact of white matter anisotropies and head restraint devices on current distribution.

Main Methods:

• A coronal MRI section of the head, including the motor cortex, was modeled using FEM.
• White matter compartments were modeled with both anisotropic and homogeneous resistivity.
• Current densities were simulated for various electrode placements and with a conductive head restraint device.

Main Results:

• FEM successfully predicted localized current densities, influenced by white matter anisotropies.
• Stimulation site location relative to brain sulci and scalp shunting affected current density.
• A conductive head restraint device was predicted to divert current away from the brain under constant current stimulation.

Conclusions:

• The interplay of head geometry and tissue resistivity significantly influences brain current distribution during TES.
• FEM modeling, incorporating white matter anisotropies, can predict these current densities.
• Conductive head restraints may be contraindicated with constant current TES; FEM could enable optimized transcranial magnetic echo potential (tcMEP) monitoring and localized brain activation.