An approach to quantifying the multi-channel EEG spatial-temporal feature

Abstract

Investigation of spatial characteristics in the multi-channel EEG (electroencephalogram) has been of great importance to the fundamental and clinical medicine. Conventional methods are mostly based on the coherence and correlation analysis in time and frequency domain. The authors present the method of quantifying the global waveform complexity in EEG by analyzing the high-dimensional state-space trajectory constructed from the multi-channel EEG. The resulting average complexity index (<(<delta>)over bar>) is well distinct between the background (4.0 similar to 4.5) and event (3.0 similar to 3.5 for the focal-sharp-wave transient) in the 5-channel case study. In addition, the running <(<delta>)over bar> measurement for different electrode arrays, for a fixed number of state-space dimension (n = 5), reveals the EEG spatial characteristic. An array composed of nearby channels with similar EEG activities tends to have a small <(<delta>)over bar>. On the other hand, the computed <(<delta>)over bar> increases as the array consists of electrode sites with spatially incorrelated EEG activities. Thus the method is capable of quantifying the spatial-temporal feature of the multi-channel EEG.