Influence of skull defects on MEG source reconstruction in an in-vivo animal experiment

Quantitative experimental evidence for the influence of skull defects on the MEG is rare. This study aims to experimentally investigate the influence of conducting skull defects on the MEG and EEG signal and source reconstruction using a controlled current source under a skull defect and a detailed finite element head model. Our results demonstrate that both EEG and MEG were influenced by a conductive skull defect with a maximal relative magnitude deviation of above 300% for EEG and above 20% for MEG. Failure to model skull defects in MEG source reconstruction can lead to localisation and orientation errors. A realistic finite element head model is able to represent a skull defect and to compensate its influence on the MEG source reconstruction. We conclude that skull defects need to be accounted for in realistic volume conductor models.