Individual and average topography of alpha power. During sevoflurane-induced unconsciousness, alpha power remains primarily in occipital cortex for four participants and undergoes some degree of anteriorization in three participants. On average, anteriorization of alpha power is not correlated with sevoflurane-induced unconsciousness. Subject six became unconscious at the first concentration of sevoflurane and thus the effective onset period is not applicable (N/A). E_ON = effect onset; Trans_CON = transition to consciousness; Trans_UN = transition to unconsciousness.