Fig. 2.
The relative power spectrum for ketamine, propofol, and sevoflurane. The relative powers for each frequency band, (A) δ (0.1–4 Hz), (B) θ (4–8 Hz), (C) α (8–13 Hz), (D) β (13–25 Hz), and (E) γ (25–35 Hz), are presented. Error bar denotes the standard error for each 10-s electroencephalogram epoch over 30 subjects. The blue shade indicates induction of anesthesia (from 5 to 7 min). The time spans for propofol and sevoflurane anesthesia were rescaled to match with the time of ketamine. Red color indicates the increase of relative power after anesthetic-induced unconsciousness, whereas blue color indicates the decrease of relative power. The relative power of α and γ demonstrated different responses among the three anesthetics. Six substates (B1, B2, B3 in baseline state and A1, A2, and A3 in anesthesia) are denoted.