EEG-based tracking of propofol and dexmedetomidine administration. Representative individual spectrogram from a frontal EEG channel to illustrate similarities and differences during dexmedetomidine sedation and propofol-induced general anesthesia. The spectrogram displays the frequency content of signals as they change over time. Frequency is plotted on the y-axis, time is plotted on the x-axis, and the amount of energy or power in the signal is indicated in color. Both spectrograms show power content in the 0.1 to 40 Hz range. (A) Spectrogram of a volunteer research subject who received dexmedetomidine for sedation. Dexmedetomidine sedation is marked by the onset of power centered on the 14 Hz frequency band. (B) Spectrogram of a volunteer research subject who received a graded dosing scheme of propofol (sedation through to general anesthesia). Propofol GA is marked by the onset of broad and power (10 to 20 Hz) that is eventually centered on the 10 Hz frequency band.