MAGNETOENCEPHALOGRAPHY IN EPILEPSY

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During the first year of the grant with a new 7-channel magnetometer we have made substantial progress in all 5 steps of the proposed research. We plan to complete the goals of the original 3 year research proposal within the 2 years awarded on the grant. We have: (1) modeled forward and inverse dipole solutions in MEG, EEG, and cortical EEG (ECoG) with goodness of fit measures and residuals; (2) modeled multiple moving dipole solutions in MEG; (3) localized the central fissure close to hand area of primary sensory cortex in 4 patients on MEG, EEG, and ECoG with moving dipole solutions, with localization errors of 4 to 6mm, verified by cortical stimulations; (4) recorded deep spikes on MEG; (5) mapped simultaneous, spontaneous MEG and ECoG of human interictal spikes; (6) verified MEG seizure localization within 1-1.5 cm by subdural recordings; (7) mapped simultaneous, spontaneous MEG and EEG of human partial seizures with dipolar patterns; and (8) implemented a 48 channel recording system for simultaneous MEG, EEG, and ECoG recording. During the final second year of the grant, we will complete all steps, mapping and localizing the center interictal spikes and seizures in multichannel MEG, EEG, and ECoG. The temporary use of a magnetically shielded room has been essential to systematic completion of steps 4 and 5. In this renewal, we propose extension of the research to more accurate epileptic source identification in a magnetically shielded room. The severe magnetic noise which has developed in our unshielded hospital environment markedly limits the natural extension of research into promising areas, developed at Reed and proved capable of study. A multichannel magnetometer in a shielded environment is essential to the systematic study of the spatiotemporal structure of simultaneous MEG, EEG and cortical EEG of the spontaneous and averaged human interictal spike and seizure. In this renewal, we request funds for salary for essential personnel and for a magnetically shielded room which we have tested during the last 2 months and the essential nature of which is shown in the progress report. We want to continue systematic investigation of MEG, comparison of MEG and EEG, and integrated use of their complementary information to identify intracranial current sources in a large number of patients to achieve statistical numbers. Funds are requested for essential consulting collaboration with Dr. Terrance Darcey of Yale University School of Medicine, New Haven, Connecticut, in MEG, EEG, and ECoG modeling. We have already obtained: (1) 39% of required funds for new equipment and (2) 36% of required funds for personnel from other sources, and those are exhausted. The funds requested here are the minimum essential to continue systematic research of the magnetic field of the human epileptic focus in a statistical number of patients.