Journal: Human Brain Mapping

Article Title: Diversity of functional connectivity patterns is reduced in propofol‐induced unconsciousness

doi: 10.1002/hbm.23708

Figure Lengend Snippet: Distinct spectral changes across different stages of anesthesia. (A) Group‐median spectrogram before, during, and after propofol administration. Propofol was administrated with infusion rate (IR) = 3 (left panel, n = 30), 6 (middle panel, n = 29), or 12 (right panel, n = 31) mg·kg−1·h−1. The IR was constant for 60 min. Higher IR (e.g., IR = 12 mg·kg−1·h−1) promotes deeper state of anesthesia. The white dotted vertical line at 0 min indicates the propofol infusion start and the second white dotted vertical line at 60 min indicates the end of propofol. (B) Time course of averaged αβ power (8–30 Hz) and δ power (0.5–4 Hz). Curves are smoothed with moving average filter. Different rates of propofol infusion induce distinct power changes. A biphasic effect of αβ power and δ power is shown with IR = 12 mg·kg−1·h−1 (right panel). Red and green arrows above each box indicate LOC and ROC points, respectively, for each subject. Vertical colored bars indicate time periods analyzed from each state: baseline consciousness (BC): black (n = 88); sedation (A1): magenta (n = 30); αβ power peak (A2): red (n = 58); slow oscillations (A3): yellow (n = 31); recovery of consciousness (RC): green (n = 69). See Methods section for state‐identification criteria. [Color figure can be viewed at http://wileyonlinelibrary.com]

Article Snippet: The same experimental protocols with same IRs were conducted on two occasions: for the first trial, long‐chain triglyceride (LCT) propofol (Diprivan ® , AstraZeneca, London, UK) was used, and for the second trial, microemulsion propofol (Aquafol™, Daewon Pharm.

Techniques:

Journal: Human Brain Mapping

Article Title: Diversity of functional connectivity patterns is reduced in propofol‐induced unconsciousness

doi: 10.1002/hbm.23708

Figure Lengend Snippet: Progressive decrease in phase‐lag pattern diversity is quantified by PLE. (A) Average PC matrix from 5 states: first col: BC (n = 88); second col: A1 (n = 30); thirs col: A2 (n = 58); fourth col: A3 (n = 31); fifth col: RC (n = 69). (B) Average PLI matrix from 5 states. PLIs between prefrontal and frontal channels are increased in A2 compared to BC and SE. From A2 to A3, prefrontal–frontal PLI decreases. (C) Average PLE matrix from 5 states. From BC through A1 to A2, PLE decreases in all EEG channel pairs. The change is most pronounced in prefrontal–frontal connections. From A2 thorough A3 to BS, PLE increases. (D) PC, PLI, and PLE from prefrontal–frontal channel pairs. The measures are averaged over 4 channel pairs (Fp1‐F3, Fp1‐F4, Fp2‐F3, and Fp2‐F4) and subjects. Compared to PC and PLI, PLE shows a progressive decrease from BC through A1 to A2 with statistical significance. The statistical significances between BC, SE, and A2 are emphasized with red colored stars. The error bars indicate standard deviation (*P < 0.05, **P < 0.01, ***P < 0.001; adjusted P values after Tukey's multiple comparison test). (E) The effects of propofol on PC, PLI, and PLE are assessed and compared over time. The curves represent the factors by which the average effect of each measure (PC, PLI, PLE, and PLEsurr) exceeds interindividual baseline variability (σ). Red arrows indicate LOC points and green arrows indicate ROC points for each subject. Curves are smoothed with moving average filter. PLEsurr is calculated after eliminating the connectivity between two signals (see Methods for details). When IR = 3 mg·kg−1·h−1 (upper panel, n = 30), PC, PLI, and PLEsurr barely change compared to their baseline values. PLE decreases monotonically during anesthesia. When IR = 6 mg·kg−1·h−1 (middle panel, n = 29), PLE shows higher ratio of changes with respect to interindividual baseline variability than PC, PLI, and PLEsurr. |PLE| > |PLEsurr| indicates that the scarcity of phase‐lag patterns under anesthesia cannot be explained solely by spectral characteristics of each signal. When IR = 12 mg·kg−1·h−1 (lower panel, n = 31), PLI, PLE, and PLEsurr show biphasic effect as in power changes. In all 3 cases, the propofol effect on PLE is most salient among the 4 measures (see Supporting Information, Fig. 2 for time course of PeEn and ApEn).

Article Snippet: The same experimental protocols with same IRs were conducted on two occasions: for the first trial, long‐chain triglyceride (LCT) propofol (Diprivan ® , AstraZeneca, London, UK) was used, and for the second trial, microemulsion propofol (Aquafol™, Daewon Pharm.

Techniques: Standard Deviation

Journal: Human Brain Mapping

Article Title: Diversity of functional connectivity patterns is reduced in propofol‐induced unconsciousness

doi: 10.1002/hbm.23708

Figure Lengend Snippet: PLE shows stronger agreement with the level of consciousness than do other anesthetic depth indicators (n = 10). (A) Representative spectrogram from a single subject during propofol sedation. Progressive decrease in peak frequency and progressive increase in αβ power are shown. Corresponding MOAA/S is illustrated as black step lines. (B) BIS, RBR, ApEn, PeEn, and PLE for 6 MOAA/S scores are visualized with boxplot. In each box, the central red mark, the bottom, and the top edges indicate the median, the 25th, and 75th percentiles, respectively. Red cross marks indicate outliers. In PLE, the boxes for different MOAA/S scores overlap to a lesser degree. PLE also has less outliers compared to other measures. The P k of PLE is higher than those of BIS, RBR, ApEn, and PeEn; this implies that PLE has the most concordant relationship with the level of consciousness. For RBR, ApEn, PeEn, and PLE, the parameters (EEG channel, reference, and embedding parameters) which give the highest P k were chosen (RBR: Fp1 for active channel, F8 for reference; ApEn: F4 for active channel, F7 for reference, m=2; and down‐sampled to 128 Hz; PeEn: F4 for active channel, F7 for reference, m=3, and τ=1; PLE: Fp1, Fp2, F3, and F4 for active channels, A2 for reference, m=3, and τ=1). Results with different parameters are shown in Supporting Information. [Color figure can be viewed at http://wileyonlinelibrary.com]

Article Snippet: The same experimental protocols with same IRs were conducted on two occasions: for the first trial, long‐chain triglyceride (LCT) propofol (Diprivan ® , AstraZeneca, London, UK) was used, and for the second trial, microemulsion propofol (Aquafol™, Daewon Pharm.

Techniques: