(A and B) Spatial distribution of average phase amplitude coupling (PAC) strength at baseline, last responsive state before loss of responsiveness (SED), loss of responsiveness (LOR), and loss of consciousness (LOC) states in the dexmedetomidine and propofol groups. In the propofol group, trough-max (negative) coupling was seen in the frontal area at SED and LOR, and peak-max (positive) in the posterior and other regions at LOC. (C–F) Box plots of signed PAC strengths in the two groups. On each box, the central mark is the median, the edges of the box are the 25th and 75th percentiles, the whiskers extend to the most extreme values, and the outliers are plotted individually. During propofol exposure, there was trough-max coupling at SED and LOR, which reverted back to neutral at LOC in the frontal region (C), and peak-max coupling at LOC in the posterior region (D). P-values for statistically significant differences within the groups are given below the boxplots and between the groups above. No significant differences in the dexmedetomidine group (E and F).