Fig. 5.

Histograms of instantaneous respiratory rate for all animals during eupnea (A; n = 9) and hypoxia-hypercapnia (B; n = 9). Histograms reflect the full range of respiratory rates across various motor behaviors including resting breathing (usually ~100 breaths/min) as well as sniffing (usually ~400 breaths/min). Sniffing behavior was apparent during eupnea in all awake animals and ceased after induction of anesthesia. Note the blunting of the response to hypoxia-hypercapnia during ketamine-xylazine anesthesia.