Spectral asymmetry of EEG signals in transition from conscious to unconscious state

We analyzed the electroencephalogram (EEG) spectral distribution during anesthesia. Especially, the spectral characteristics of alpha band(8~12Hz) at the frontal head were investigated. Using skewness and kurtosis, the asymmetry of spectral distribution was quantified. A set of EEG data from 10 subjects was obtained during general anesthesia with Propofol (dose rate of 12mg/kg/h). We observed distinct changes in spatial distribution of EEG spectrum near loss and recovery of consciousness. Also, spectral asymmetry was quantitatively measured in terms of skewness and kurtosis. These findings can be used for developing measures of the depth of anesthesia.