Fig. 2.

Spatial and functional characterization of respiratory neurons in the horizontal slice. (A) Locations of 47 inspiratory neurons recorded from 12 horizontal slices (200-µm grid), and three example excitatory (red; 1–3) and inhibitory (blue; 4–6) neurons. Raster plots show spiking activity over 30 consecutive inspiratory bursts; solid lines show integrated spiking activity (population burst onset at t = 0). Note the decrementing spiking pattern of inhibitory neurons. (B) Locations of 12 expiratory and 6 postinspiratory neurons recorded from 6 horizontal slices. Raster plots (Right) show a representative expiratory neuron with modest postinhibitory rebound activity (7), an excitatory postinspiratory neuron that is also active during inspiration (8), and an inhibitory postinspiratory PiCo neuron. Note that strong postinspiratory bursts only occur during some cycles in the absence of norepinephrine. (C) Quantified rostrocaudal locations of excitatory (red) and inhibitory (blue) inspiratory, expiratory, and postinspiratory neurons relative to the VII nerve (*P < 0.05; means ± SEM).