Fig. 3.
Flow diagram of the analysis algorithm in the middle. On the left, the intermediate results of the algorithm are shown of participant 1 (table 1) during the baseline measurement. On the right are the results of the same participant during the 40% end-tidal nitrous oxide exposure. A–C are from the signals of the Fp1 electrode (yellow circle in D). The analysis steps are repeated for each channel separately. (A) Absolute cross-correlation values (blue, low; yellow, high) between the electroencephalogram samples. (B) Dichotomized results (0, black; 1, white). (C) Probability distributions of the diagonal line lengths. (D) Surface head plot with contour lines of the Shannon entropy for all electrodes, showing the spatial distribution of temporal complexity (blue, low; yellow, high). The red line indicates the contour with value 1, in which the electrodes with a value above 1 at baseline (in yellow/green) are enclosed (red ×). This selection is consistent over exposures and forms the region of interest for the electroencephalogram default-mode-network complexity analysis.