Figure 4.

Stimulation of RTN neurons entrains the respiratory cycle and induces active expiration. A, DIA_EMG and ABD_EMG during phasic stimulation of RTN neurons. Phasic stimulation (1.5 Hz) entrains the respiratory cycle and triggers a burst of ABD_EMG in the late-expiratory phase (E2). B, DIA_EMG and ABD_EMG during phasic stimulation of C1 neurons. C1 phasic stimulation entrains the respiratory cycle but does not elicit active expiration. I, Inspiration; PI, post inspiration (also known as E1 phase); E2, late-expiratory phase. C, Waveform averages of DIA_EMG and ABD_EMG showing the relationship between the phase of the respiratory cycle and the entrainment stimulus for RTN cases. D, Waveform averages of DIA_EMG and ABD_EMG showing the relationship between the phase of respiratory cycle and the entrainment stimulus for C1 cases. E, Respiratory cycle represented in 360° showing the phase of the respiratory cycle when stimulus entrains breathing for RTN (n = 5) and C1 (n = 5) stimulation. Student's t test: RTN versus C1, p = 0.4735. F, Phase angle of the ABD_EMG peak elicited by phasic RTN stimulation. In 1 rat, phasic RTN stimulation entrained the respiratory cycle but did not activate ABD_EMG. In this animal, active expiration occurred only during 20 Hz continuous stimulation.