Directional couplings between the respiration and parasympathetic control of the heart rate during sleep and wakefulness in healthy subjects at different ages

FIGURE 1. Fragments of a respiratory signal (A) and a sequence of RR-intervals (B) for one of the young subjects in the awake state. Filtered signals x 1(t) (C) and x 2(t) (D).

FIGURE 2. Indices of directional coupling between the respiration and the process of parasympathetic control of the heart rate. (A) Values of ρ1max (red crosses) and ρ2max (blue circles) for the subjects of different age. (B) Box-and-whisker diagrams for the values of ρ1max and ρ2max for all records. (C) Values of δ for the subjects of different age. (D) Distribution of index δ.

FIGURE 3. (A) Box-and-whisker diagrams for the values of ρ1max (red) and ρ2max (blue) in the awake state, LS, DS, and REM sleep for all subjects. (B) Box-and-whisker diagrams for the values of δ in the awake state, LS, DS, and REM sleep. Both in (A) and (B), the box boundaries are the first and third quartiles, the horizontal line is the median, and the whiskers are the minimum and maximum values.

FIGURE 4. (A) Box-and-whisker diagrams for the values of ρ1max (red) and ρ2max (blue) for the subjects of different age. (B) Box-and-whisker diagrams for the values of δ for the subjects of different age. Both in (A) and (B), the box boundaries are the first and third quartiles, the horizontal line is the median, and the whiskers are the minimum and maximum values.