Fig. 3. Population data for all recording sites when cranial isoflurane was 1.1 ± 0.3% and torso isoflurane was 1.2 ± 0.3%. There were no significant changes after application of the noxious stimulus. Electroencephalographic (EEG) power is expressed as μV². Note that the Y scales (EEG power) differ among the various graphs. MRF = midbrain reticular formation.