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. 2015 May 22;593(Pt 13):2909–2926. doi: 10.1113/JP270053

Figure 8. Phasic retrotrapezoid nucleus stimulation selectively shortens the post-inspiratory phase.

Figure 8

A and B, event-triggered waveform averages of the plethysmography signal during light-induced breathing entrainment in one rat during non-REM sleep (A) and during quiet wake (B). ChR2-transduced retrotrapezoid nucleus neurons were photostimulated with trains of 4 × 3 ms long light pulses (20 Hz; represented as vertical blue bars) delivered at various frequencies between 1.1 and 18 Hz. Active expiration (large flow signal immediately preceding inspiration) was observed only during quiet wake periods. During non-REM sleep we measured only the I and E phases. During quiet wake, the duration of the late expiratory flow peak was defined as the E2 phase and the post-inspiratory phase (E1) represents the balance of the expiratory duration. C and D, group data from eight animals. Effect of stimulation frequency on the various phases of the breathing cycle evaluated using unpaired, non-parametric one-way ANOVA (Kruskal–Wallis). E, expiration; I, inspiration.