Contingency tables showing the proportion of experimental animals that responded to ampakine CX717 or HPCD with an acute increase in phrenic bursting. This was defined as an increase in the amplitude of the integrated phrenic inspiratory burst that was at least 10% above the baseline (pre-infusion) values. The CX717 group includes all animals that received CX717 (e.g., n=8 ampakine and n=8 ampakine + hypoxia). For the latter group, data were evaluated immediately prior to the hypoxia exposure. P-values represent the results of Fisher’s exact test of proportions in small sample sizes.