Figure 4.

A REM sleep-like episode triggered after clonidine was injected into the A5 region on the left and then right side. The injection marker shows the second of the two injections. Trace labels and figure format are the same as for Figure 3. In this case, inspiratory activity of the XII nerve was transiently abolished at the peak of the response. One can also note that the central respiratory rate was reduced just before the disappearance of XII nerve activity and just after it reappeared when compared with the pre-injection period. The power spectra for the control period and the period centered on the peak of the response are shown with open and filled circles, respectively.