Comparison between auto-cross-correlation coefficients and coherence methods applied to the EEG for diagnostic purposes.
BACKGROUND: Power-spectrum and coherence analysis of the EEG has often been applied in the study of various forms of brain dysfunction. The examination of differences in intra-hemispheric coherence and a novel method based on auto-cross-correlation algorithms between the left and right hemispheres of the same EEG are investigated in this paper. MATERIAL/METHODS: Both coherence and the proposed method are computed from the same EEG segment across the EEG spectrum (0-64 Hz). In this experiment, five EEGs of different patients with severe brain damage were used. The novelty of this study lies in the fact that the autocorrelation coefficients are extracted in a particular spectrum, in contrast to the traditional coherence method, which is based on a measure of the square of the linear association between the two EEG signals from the entire EEG spectrum. RESULTS: The results of the application of coherence and the proposed method showed that particular pairs of symmetrical cortex channels differed dramatically in specific damaged areas. CONCLUSIONS: Statistical analysis of the above results showed that the proposed method is more accurate than coherence because it could recognize the cases of the patients to a significant statistical degree, whereas the coherence method showed weakness in recognizing them.