Topographic and temporal spectral analysis of EEG signals during anaesthesia

In this study, we present the spatial and temporal evolution of EEG signal spectrum under anaesthesia. Studied features include SEF-90, α-β power ratios, spectral entropy that are known to be used in commercially available depth of anaesthesia monitors. As an additional and comparing feature, we also present Higuchi fractal dimension that is used for analysis of non-linear systems. By means of spatial analysis, we verified the shift of occipitally dominant alpha activity to frontal regions and demonstrated corresponding topographic plots.