Does hyperbaric oxygen cause narcosis or hyperexcitability? A quantitative EEG analysis

Figures

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  FIGURE 1. Oxygen measurements. Top row describes the order of steps during the oxygen measurement session. Measurements were conducted at air baseline, 100% oxygen measurement at 101, 142, and 284 kPa, with the last two in randomized order. The bottom row represents the recording order at each exposure. During each measurement, EEG, end‐tidal CO2, psychometric test, critical flicker fusion frequency (CFFF), and again EEG and end‐tidal CO2 were recorded. Each measurement was finished with the NASA task load index and Karolinska sleepiness score questionnaires. Air baseline measurement did not have an acclimatization step.

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  FIGURE 2. Box plot of the psychometric test results (reaction time and accuracy) combined metric (left) and the differences between exposures and air baseline (right). The box plot shows the median (red line), interquartile range (blue box) and the whiskers showing the full range of the data. Outliers (red +) are values larger than 1.5 times the interquartile range.

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  FIGURE 3. Average power in dB for each electrode (placed according to their head map location, title is the electrode name) and the mean of all electrodes (bottom right) of all participants. Each subfigure has the four exposures on the x‐axis (air baseline, oxygen at 101, 142, and 284 kPa) and four frequency bands on the y‐axis (bottom to top: Delta [1–4 Hz], theta [4–8 Hz], alpha [8–14 Hz], and beta [14–30 Hz]).

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  FIGURE 4. Box plot of mutual information based global efficiency metric in the alpha band (left) and the differences between exposures and air baseline (right). The box plot shows the median (red line), interquartile range (blue box), and the whiskers showing the full range of the data.

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  FIGURE 5. Box plot of EEG DMN complexity metric (in bits) (left) and the differences between exposures and air baseline (right). The box plot shows the median (red line), interquartile range (blue box), and the whiskers showing the full range of the data. Outliers (red +) are values larger than 1.5 times the interquartile range.

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  FIGURE 6. Average surface head plots with contour lines of the Shannon entropy (in bits) for all electrodes (blue low, yellow high) for each of the exposures of all participants.