An autoregressive method for the measurement of synchronization of interictal and ictal EEG signals

We propose a new measure of synchronization of multichannel ictal and interictal EEG signals. The measure is based on the residual covariance matrix of a multichannel autoregressive model. A major advantage of this measure is its ability to be interpreted both in the framework of stochastic and deterministic models. A preliminary analysis of EEG data from three patients using this measure documents the expected increased synchronization during ictal periods but also reveals that increased synchrony persists for prolonged periods (up to 2 hours or more) in the postictal period. Key words: neural synchronization, epilepsy, multichannel autoregressive model, nonlinear dynamics, seizure 1 Introduction Epileptic seizures are by nature episodic events. Experimental models of epilepsy, as well as patient observations, suggest that the transition to ictal events is characterized by an abnormal increase in synchronization of neural activity. 1 Corresponding author. Tel.: 410-706-2805; Fax: 41..