Volume currents in forward and inverse magnetoencephalographic simulations using realistic head models

Area of Science:

• Biophysics
• Computational Neuroscience
• Medical Imaging

Background:

• Accurate magnetoencephalography (MEG) simulations require precise modeling of electromagnetic fields.
• Realistic head models are crucial for interpreting MEG data, but incorporating all current types presents challenges.

Purpose of the Study:

• To evaluate the impact of volume currents on MEG forward and inverse simulations in realistic head models.
• To compare simulation accuracy between models with and without volume currents.

Main Methods:

• Finite element method (FEM) implementation for MEG simulations.
• Verification of FEM accuracy using analytical solutions for spherical models.
• Comparison of forward solutions across different head models (spherical, realistic without volume currents, realistic with volume currents).

Main Results:

• FEM implementation accurately reproduces analytical solutions for simple models.
• Volume currents contribute significantly to the magnetic field in realistic head models, often comparable to primary fields.
• Realistic head models incorporating volume currents yield more accurate MEG forward and inverse solutions.

Conclusions:

• Volume currents are essential for accurate MEG simulations in inhomogeneous, realistic head models.
• Ignoring volume currents leads to substantial inaccuracies in both forward and inverse MEG calculations.
• The finite element method provides a robust approach for including volume currents in advanced MEG modeling.