Improved Source Localization of Auditory Evoked Fields using Reciprocal BEM-FMM.

We apply our recently introduced technique of reciprocal magnetoencephalographic (MEG) source estimation via the boundary element fast multipole method (reciprocal BEM-FMM) to localize auditory evoked fields (AEFs). We compare our results with the source estimates of MNE-Python against simulated N1m components of AEFs, as well as experimental data for a cohort of 7 participants subjected to binaural auditory stimulation. Previous comparisons of reciprocal BEM-FMM with MNE focused on evoked somatosensory fields, which produced results of similar quality. In this work we show that the localization of AEFs using high-resolution reciprocal BEM-FMM is significantly better in terms of accuracy and focality than those estimates of the low resolution 3-layer BEM of MNE. Our findings suggest that the use of high-resolution models plays a significant role in the quality of source estimates and that these may provide improvements in a wide range of applications.