A continued collaboration with the Naval Research Laboratories has enabled a SQUID magnetometer to be used to study inter-ictal spike discharges in epileptic patients. Correlation of the MEG activity and the corresponding EEG signal for these discharges permits signal averaging of spikes associated with the same neurologicl event. These mesurements allow a magnetic field map at the surface of the scalp to be obtained from which a prediction of the source of the epileptic focus can be made. Computer and electronic processing techniques have been developed to analyze these MEG and EEG signals with the aim of producing an efficient method of localizing the sources of the epileptic discharges in a selective manner. Several patients have been scanned using these techniques. To enhance the collection of MEG data associated with a single spike discharge, a seven channel array detector has been specified and will be installed shortly. Magnetic field maps generated on patients going to surgery predicted epileptic source localization consistent with intraoperative electrical recordings. Refinements of the mapping procedures including MEG normalization by EEG spike amplitude and modeling of contributions of non-sphericity of the scalp over the temporal lobe appear to be substantial improvements in the state-of-the-art.
