Fig. 3. (A ) Auditory steady state response (ASSR) and (B ) BisPectral index (BIS) amplitudes (mean ± SD) for all subjects (n = 17) during baseline (awake) and propofol-induced unconsciousness. Amplitudes were significantly reduced when subjects were unconscious compared with when they were awake (****P < 0.0001). Numbers above each histogram plot indicate (SD).