Influence of white matter anisotropy on EEG source localization: an experimental study

Area of Science:

• Neuroscience
• Biophysics
• Medical Imaging

Background:

• Electroencephalography (EEG) is a crucial tool for non-invasively studying brain activity.
• Accurate source localization in EEG is vital for understanding neural processes.
• White matter (WM) anisotropy, the directional dependence of its conductivity, may influence EEG signal propagation.

Purpose of the Study:

• To experimentally investigate the impact of white matter (WM) anisotropy on electroencephalography (EEG) source localization accuracy.
• To compare EEG source localization using anisotropic versus isotropic WM conductivity models.
• To assess the influence of WM anisotropy on localizing activity within the primary visual cortex (V1).

Main Methods:

• Acquired simultaneous visual evoked potential (VEP) and functional magnetic resonance imaging (fMRI) data from three subjects.
• Constructed finite element method (FEM) head models with and without WM anisotropy.
• Performed single-dipole source localization using the N75 VEP component.
• Quantitatively compared localized dipole positions with fMRI-identified V1 activation centers.

Main Results:

• A slight reduction in the distance between the localized N75 dipole and fMRI V1 activation was observed with anisotropic models.
• The difference in localization accuracy between anisotropic and isotropic models was minimal.
• Anisotropic WM conductivity models did not yield a significant improvement in EEG source localization accuracy within V1.

Conclusions:

• Incorporating realistic WM anisotropic conductivity distributions into head models does not significantly enhance EEG dipole localization accuracy in the primary visual cortex.
• Conventional isotropic models may be sufficient for EEG source localization in this context.
• Further research may explore other factors influencing EEG signal propagation and source localization accuracy.