Fig. 4.
Group level electroencephalography source power with most statistically significant effects under xenon and nitrous oxide anesthesia. Loss of responsiveness at 1.30 MACawake xenon (Xe) administration (A) yields pronounced widespread increases in low-frequency delta and theta activity. Nitrous oxide (N2O) effect (B) is a reduction in alpha activity that is global and more pronounced for 0.50 MACawake N2O. 0.75 MACawake N2O effects were subtle and centered on frontal and temporal regions. There were no statistically significant high-frequency power changes. Maximum statistics and Bonferroni corrected t-maps ([top row] Xe, P = 0.004; N2O, P = 0.005) of electroencephalographic sources across participants (n = 19). Brain slices (middle row) display region specific alterations plotted on the template Montreal Neurological Institute and Hospital (MNI) brain. Electroencephalography source spectral power ([bottom row] 1 to 45 Hz) is shown in the logarithmic scale for the postantiemetic baseline and the highest administered doses of the two gases averaged across all electroencephalographic sources and all subjects. Delta, 1 to 4 Hz; theta, 4 to 8 Hz; alpha, 8 to 13 Hz. MACawake, minimum alveolar concentration–awake.