Fig. 7.

Preinspiratory hyperpolarization begins earlier with phasic inflation in type III neurons. A, Raw traces of type III neuron membrane potential with and without phasic inflation are displayed as in Figure 3. In both control and phasic inflation cycles, type III neuron membrane potential shows consistent preinspiratory inhibition. B, Burst-triggered average of seven cycles from one type III neuron, displayed as in Figure 3. Bar and column graphs show mean values for all five type II neurons and are scaled to the axes of the averaged traces. Preinspiratory hyperpolarization onset occurs significantly earlier (p < 0.05) during phasic inflation (bottom, black bar) than in control cycles (bottom, white bar). Preinspiratory hyperpolarization amplitude (right,black column) and inspiratory burst onset are the same with and without phasic inflation. Phasic inflation significantly shortens (p < 0.01) type III inspiratory firing duration, from 1450 ± 170 msec (top,white bar) to 890 ± 80 msec (top,black bar).