Multielectrode analysis of the electrocorticogram in temporal lobe epilepsy

An analysis of electrocorticographic data recorded from humans afflicted with acute temporal-lobe epilepsy is presented. Subdural recordings of the ictal phase have a characteristic electrical signature; they display large power and rhythmic patterns. At the onset of this phase the mean power at locations close to the focus shows a rapid increase followed by an exponential decay from its maximal value. Power spectra density estimates of signals at these sites reveal an evolution of the peak frequency and spectral spread. Multichannel spectral analysis discloses a greater coherence prior to and during the ictal discharge at sites close to the focus that at those farther away. The evolution of the mean power, peak-frequency, bandwidth, and coherence relationships allows possible mechanisms of the spread of ictal activity to be inferred and aids in the localization of the focus.<>