A simple method for 3-dimensional localization of epileptic activity recorded by simultaneous EEG and MEG

A simple method is presented to average target patterns in the magnetoencephalographic trace of epileptic activity by finding markers in an EEG channel. This method proves to be useful even in cases of low magnetic signal-to-noise ratio. After simultaneously recording electric and magnetic activity the user chooses in the electric trace a template of interest and determines within the same trace all the time points at which the EEG pattern is highly correlated with the chosen template. The magnetic trace portions recorded at those times are averaged together, extracting in this way the magnetic signal from the noise. The MEG results are applied to localize in the brain the active sources that contribute to the recorded signals.