Fig. 9.

Vagal sensory feedback limits the refractory period for excitatory preBötC populations. a, b Example integrated XII nerve activity during brief (100–200 ms) light stimulation at different time points within the respiratory cycle in vagus-intact (a) and vagotomized (b) Dbx1-ChR2, Vglut2-ChR2, and Vgat-ChR2 mice. Note the difference in the refractory period for partially overlapping Vglut and Dbx1 populations in vagus-intact mice. Arrows indicate failed bursts near the end of the refractory period. Traces are scaled to the expected duration of the respiratory cycle (expected phase). c, d Quantified phase shift elicited during stimulations across the respiratory cycle (stimulus phase 0 = beginning of inspiration) in vagus-intact (c) (Dbx1, n = 10; Vglut2, n = 10; Vgat, n = 5; Cre−, n = 9) and vagotomized mice (d) (Dbx1, n = 9; Vglut2, n = 7; Vgat, n = 3; Cre−, n = 9; mean ± s.e.m.). Data from Cre− control mice shown in black. Refractory periods for Dbx1-ChR2 (blue) and Vglut2-ChR2 (green) shown on equivalent time scales relative to the average respiratory cycle duration in vagus-intact and vagotomized conditions. Note the exaggerated refractory period in vagotomized mice and the minimal effect of Vgat-ChR2 stimulation during the refractory period