Directed coherence analysis of normal and abnormal alpha activities

This report concerns with the results of causal analysis of the diffuse distributed alpha type EEG with frequencies between 7.0 Hz and 13.5 Hz which are selected from our EEG data base. We have introduced a new parameter which indicates causal relation between different points on the scalp which we have named"directed coherence." Directed coherence analysis can express correlation with directions between time series in the frequency domain. By the result of this directed coherence analysis we have revealed an interesting common "structure" of the "causal" relations for eight scalop positions despite of alpha peak frequencies