Type III intermittency in human partial epilepsy

A rigorous characterization of the dynamic regimes underlying human seizure s is needed to understand, and possibly control, the transition to seizure. Intra- or extracranial brain electrical activity was recorded in five pati ents with partial epilepsy, and the interictal and ictal activity analysed to determine the dynamics of seizures. We constructed first-return one-dime nsional maps by fitting the scatter plots of interpeak intervals. The featu res of the mapping indicated that type III intermittency is the dynamic cha racteristic of the ictal events. This was confirmed using histograms of the durations of the regular phases during seizures. The intermittent regime e xplains the abrupt transitions observed during ictal events in terms of tra nsient stabilization of the unstable steady state.