Fig.5. The effects of tonic changes in lung pressure and inspired CO₂ content on the temporal coordination of trigeminal (V_m) and vagal nerve (X_l) discharge of unidirectionally ventilated Rana catesbeiana. Note that positive values for the delay indicate that the vagal discharge began after the trigeminal discharge, while negative values indicate that the vagal discharge was initiated first. Values are means ± S.E.M. (N=6).