Nonlinear analysis of epileptic activity in rabbit neocortex

Abstract. We report on the nonlinear analysis of electroencephalogram (EEG) recordings in the rabbit visual cortex. Epileptic seizures were induced by local penicillin application and triggered by visual stimulation. The analysis procedures for nonlinear signals have been developed over the past few years and applied primarily to physical systems. This is an early application to biological systems and the first to EEG data. We find that during epileptic activity, both global and local embedding dimensions are reduced with respect to nonepileptic activity. Interestingly, these values are very low (dE ≈ 3) and do not change between preictal and tonic stages of epileptic activity, also the Lyapunov dimension remains constant. However, between these two stages the manifestations of the local dynamics change quite drastically, as can be seen, e.g., from the shape of the attractors. Furthermore, the largest Lyapunov exponent is reduced by a factor of about two in the second stage and cha...

• Type: Journal
• Year: 1998
• Where: BC
• Authors: J. Sarnthein, Henry D. I. Abarbanel, H. Pockberger
• Keywords: BC 1998, Epileptic Activity, Local Dynamics, Rabbit Visual Cortex