Correlation Between Depth and MEG/EEG Surface Recordings in Auditory Cortex. Contribution of Numerical Simulations

The main purpose of our study is to combine three different methods of brain activity recordings: depth recordings (stereotactic EEG: SEEG) and surface recordings (EEG/MEG) in order to improve localizations of the sources of the brain activity. We present here the first step of this study. We built a model of a region of interest (ROI) within the brain based on MRI information. Our goal was to obtain an accurate description of the surface of the ROI. According to this model, we defined realistic dipole layers in respect to the anatomy (orientation, shape, extension). By activating those dipole layers we produced SEEG, EEG and MEG theoretical signals. In order to validate this concept on a physiological point of view, we chose the auditory cortex as the ROI. We compared the simulations with in vivo signals (Auditory evoked potential (AEP)) for which Liegeois-Chauvel et al [1] studied the localization of the middle latency components using SEEG. We performed the validation by taking into account the auditory cortex anatomy and built the simulations for each patient studied. We then compared the theoretical results with the real SEEG data. Furthermore we used those simulations to test the reliability of several MEG sources modeling algorithms.