Fig. 1. The effects of exposing brainstem preparations to acute hypoxia on (A) lung burst frequency (N=7 in each group) and (B) buccal burst frequency. These experiments were performed on brainstems from pre-metamorphic tadpoles (grey) and adult bullfrogs (black). Representative trigeminal neurograms (V, trigeminal nerve) showing changes in fictive breathing during hypoxia are shown on the right. Note that the neurograms shown in B correspond to parts of those in A but on shorter time scale, to illustrate the two types of fictive breathing movements produced by this preparation. For these neurograms, the y-axis scales are the same in both panels. Values are means ± s.e.m. ^*Value statistically different from baseline at P<0.05.