Frontal cerebral oxygenation asymmetry: intersubject variability and dependence on systemic physiology, season, and time of day

Figures

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  Fig. 1. (a) FCOA of StO2 at the PFC sorted in descending order on the individual subjects. (b) Asymmetry of [tHb] and absolute values of (c) StO2, (d) [tHb], (e) PETCO2, (f) HR, (g) RR, and (h) PRQ displayed according to the ΔStO2 sorting, at the PFC for individual subjects during resting state. The median and the IQR are shown for each subject.

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  Fig. 2. Diamond box plots showing distributions of absolute (a) StO2 and (b) [tHb] values at the R-PFC and L-PFC, (c) StO2, (d) [tHb], (e) PETCO2, (f) ΔStO2, (g) ΔtHb, (h) HR, (i) RR, and (j) PRQ values in resting state. The diamond spans the first quartile to the third quartile (IQR). A segment inside the diamond shows the median and whiskers above and below the box plots represent the 95% prediction interval. The asterisks indicate the level of high significance between absolute StO2 values of the R-PFC and L-PFC (*p<0.001, Wilcoxon signed-rank test). Outliers are not displayed.

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  Fig. 3. (a) Correlation matrix of bivariate scatter plots of ΔStO2, ΔtHb, StO2, [tHb], PETCO2, HR, RR, and log(PRQ). The best nonlinear fit is presented for pairs with a significant correlation (red: significant correlation proved by both FDR-corrected and uncorrected p values; blue: only uncorrected p value). The level of significance is calculated from goodness-of-fit results. The red and blue shaded areas show 95% of confidence intervals. Outliers are not displayed. (b) Bar chart of r- and ε values for each pair of ΔStO2, ΔtHb, StO2, [tHb], PETCO2, HR, RR, and log(PRQ) parameters (sorted in descending order of r-values). ε values <−0.5, near-zero (−0.5<ε<0.5), between 0.5 and 1, and >1 are indicative of no, inconclusive, moderate, and strong correlation, respectively. (c) Bar chart of ICC values for all cerebral and cardiorespiratory parameters. Error bars represent the 95% confidence interval. The reliability of the ICC is indicated.

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  Fig. 4. Changes in StO2, [tHb], ΔStO2, and ΔtHb due to time of year [infradian changes (a)–(d)] and time of day [circadian changes (e)–(h); morning: 7:00–9:30 and 9:30–12:00; afternoon: 12:00–14:30 and 14:30–17:00; evening: 17:00–19:30 and 19:30–22:00] for females (orange) and males (green). Cosinor model and the sum of 2 cosines function are fitted to infradian and circadian changes, respectively (female, dark orange lines; male, dashed green lines). Error bars represent the 95% confidence interval.

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  Fig. 5. Changes in temperature with (a) time of year and (b) time of day. Dependence of (c) StO2, (d) [tHb], (e) ΔStO2, and (f) ΔtHb on temperature. The lines represent a linear fit and the shaded areas and error bars show 95% confidence intervals. Outliers are not displayed.

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  Fig. 6. The scatter plots show the dependence of StO2, [tHb], ΔStO2, and ΔtHb on chronotype (Horne-Östberg index) and mood (positive affect scale of PANAS). Correlations between the data are indicated by a linear fit, and the red shaded areas indicate 95% confidence intervals. Outliers are not displayed.