FIG. 11.

In vivo VRC neuronal activity profiles during control, hypoxic gasping, and recovery. A–F: firing rates of 10 simultaneously recorded VRC neurons and efferent phrenic nerve activity during the prestimulus control period (A), hypoxia-induced gasp-like activity (B), and re-oxygenation (C–F). G: control respiratory cycle-triggered histograms for neurons in A; 37 cycles averaged. One inspiratory neuron had a relatively uniform firing rate during the inspiratory phase and was designated “I-plateau” (I-Plat); H: integrated phrenic nerve activity profiles detail control, gasping, and a return to eupneic-like phrenic patterns with superimposed augmented bursts. Pattern with dashed line ellipse is similar to the phrenic activity profile observed in model simulations as shown in Fig. 10. See text for details.