Temporal dynamics of EEG during anesthesia

The study of electrical brain activity (EEG) during anesthesia has received much attention over recent years. This can be attributed to the fact that such study has vast clinical and research implications. In this work we study how the linear temporal dynamics of EEG activity are affected by the administration of anesthetic agents. The measure of lagged auto-correlation (LAC) is applied to the EEG activity of 10 patients undergoing routine surgery and the evolution of the LAC features is tracked during transitions between wakefulness/unconsciousness. We report a reversible and widespread increase in LAC during anesthesia, with decreased variability compared to wakefulness. This corresponds to a less complex EEG activity during anesthesia as a result of anesthetic administration and suggests the future utilization of LAC as a feature for discriminating between wakefulness and anesthesia.