From: Distinct Cortical Signatures Associated with Sedation and Respiratory Rate Depression by Morphine in a Pediatric Population Anesthes. 2016;125(5):889-903. doi:10.1097/ALN.0000000000001303 Figure Legend: Study design and polysomnography data. In morphine group, baseline data were analyzed during a 30-min period starting 60 min before morphine was administered (A). Postadministration data were analyzed 30 min after morphine administration over a 30-min period. In control group, data were analyzed for 30 min at 9:00 pm and for another 30 min at 10:00 pm, which corresponds to the averaged time period when data were analyzed in morphine group. Electroencephalography (EEG) recordings were performed using eight cranial electrodes (F3, Fz, F4, C3, Cz, C4, O1, and O2), two ear electrodes (A1 and A2), and two mastoid electrodes (M1 and M2) that were positioned according to the international 10:20 system (B). The 10:20 system ensures standard placements of electrodes and reproducibility.21 Respiratory recordings were analyzed from expired carbon dioxide partial pressure changes or nasal flow (C). Power spectral density was calculated between 0 and 30 Hz (D) and divided into frequency bands (E). C3, Cz, and C4 = central electrodes; C4-M1 = derivation from C4 and M1 electrodes; ECG = electrocardiogram; F3, Fz, and F4 = frontal electrodes; O1 and O2 = occipital electrodes; O2 sat = blood oxygen saturation. Date of download: 10/15/2017 Copyright © 2017 American Society of Anesthesiologists. All rights reserved.