Global Interactions Analysis of Epileptic ECoG Data

GUILLERMO J. ORTEGA*^, RAFAEL G. SOLA,* AND JESUS PASTOR*

Mar del Plata

Conferencia; XV Conference on Nonequilibrium Statistical Mechanics and Nonlinear Physics; 2006

Localization of the epileptogenic zone is an important issue in epileptology, even though there is not a uniquedefinition of the epileptic focus. The objective of the present study is to test ultrametric analysis to uncover cortical interactionsin human epileptic data. Correlation analysis has been carried out over intraoperative Electro-Corticography (ECoG) datain 2 patients suffering from temporal lobe epilepsy (TLE). Recordings were obtained using a grid of 20 electrodes (5x4)covering the lateral temporal lobe and a strip of either 4 or 8 electrodes at the mesial temporal lobe. Ultrametric analysiswas performed in the averaged final correlation matrices. By using the matrix of linear correlation coefficients and theappropriate metric distance between pairs of electrodes time series, we were able to construct Minimum Spanning Trees(MST). The topological connectivity displayed by these trees gives useful and valuable information regarding physiologicaland pathological information in the temporal lobe of epileptic patients.