Excitation of CaMKIIa⁺ neurons in the parabrachial nucleus region only caused minor reductions in delta oscillations and did not affect recovery time with high-dose dexmedetomidine anesthesia. (A) Example spectrograms showing the spectral power for 0 to 50 Hz over time in the prefrontal electroencephalogram after intraperitoneal injections of saline (top) and clozapine-N-oxide (bottom) in the same rat. The black bar over the spectrograms indicates the time when the dexmedetomidine infusion (4.5 µg · kg⁻¹ · min⁻¹ for 10 min) took place. Clozapine-N-oxide or saline injections were given before the start of the dexmedetomidine infusion. A solid vertical line represents the time of recovery for each example experiment. (Note: the transient dip in delta power at the end of dexmedetomidine administration in both [A] and [B] is due to our handling the rat to place it on its side.) Example electroencephalogram traces to the right of each spectrogram are bandpass-filtered from 0.5 to 4 Hz and show similar delta amplitude with and without parabrachial nucleus region excitation. The arrow over the spectrograms indicates the time, for both conditions, when the traces were taken. (B) Summary of power differences over time shows minor decreases in delta power for clozapine-N-oxide experiments relative to saline experiments. Time periods that show statistically significant differences with 99% confidence are indicated by black bars above the dashed zero line, representing lower power in the clozapine-N-oxide condition. Spectrograms in (A) and summary power in (B) have the same time axes. (C) No statistically significant differences between conditions were seen in recovery times, as measured by time to return of righting reflex.