MAGNETOENCEPHALOGRAM IN EPILESPY

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We have completed 3/5ths of the goals of the grant, making progress in all 5 steps of the research. We will complete the major goals of the grant within the time awarded on the grant. The 7 channel magnetometer, shielded room, and PPI are working beyond expectations in the same fiducial coordinates for MEG, EEG, ECoG, and MR scans using PPI resolution of < 1mm, excellent signal-to-noise ratios for spontaneous spikes and seizures, and adequate spatial coverage of the special coplanar wide gradiometer hexagon to capture a phase reversal and null point of spontaneous seizures and spikes during simultaneous ECoG. We have studied a large number of events in more patients. We have determined that a comprehensive study of a each patient improves localization accuracy and comparisons and that larger patient sample size is necessary to test further hypotheses. We will extend research in each step of the 5 step approach. We propose to study a larger number of patients with complete studies of MEG, EEG, and ECoG for implanted dipoles, evoked responses, and spontaneous spikes and seizures in each patient. We want to investigate propagation patterns of spikes and seizures for more accurate quantification of epileptic areas, of potential importance for surgical treatment. We plan to compare 7 MEG + 60 EEG channels to 37 MEG + 60 EEG channels to determine the added value of a large array MEG system and an upgrade to first derivative gradiometers. We believe the combination of 7 MEG and 60 EEG channels can answer important questions similar to a larger array MEG system. We will use and improve multiple fixed dipole solutions in MEG, EEG, and ECoG with MR information in individual patients to improve model estimates, an EEG 4 shell model with measurements of conductivities in individual patients, a basic finite element model, localizations of digit rostrocaudal bands, and localizations of spontaneous partial seizures in simultaneous MEG+EEG and MEG+ECoG. We will make a detailed comparison of spatiotemporal structure from multiple source modeling between the better understood evoked response and the less understood spike and seizure. We request no new equipment. We request funding for maintenance costs for the 7 channel system, salary for the principal investigator and a technologist, travel for consultants on modeling, and supplies including liquid helium. The funds requested here are the minimum essential to continue systematic research of physical interpretation of the magnetic field and scalp and cortical electric field in a statistical number of patients to describe non-invasively the spatiotemporal structure of medically intractable partial seizures for presurgical localization.