Figure 13.

Results from different laboratories and different animal models consistently indicate that antagonism of glycinergic inhibition at the motoneuronal level by strychnine does not abolish the REM sleep-related depression of activity in orofacial motoneurons. (A) In chronically instrumented, behaving cats, microinjections of strychnine into the trigeminal motor nucleus only marginally diminished the REM sleep-related depression of reflexly elicited activation of the masseter muscle. (Modified from Fig. 3 in Ref. 505 and republished with permission from Elsevier.) (B) In unanesthetized, decerebrate cats, the REM sleep-like depression of spontaneous activity of the XII nerve elicited by microinjection of a cholinergic agonist, carbachol, into the dorsomedal pontine tegmentum was well maintained despite microinjections of strychnine into the XII nucleus. (Modified from Fig. 5 in Ref. 273 and republished with permission from Elsevier.) (C) REM sleep atonia of the masseter muscle was not reduced in naturally sleeping rats by continuous microperfusion of strychnine into the trigeminal motor nucleus. QW, quiet wakefulness. (Data extracted and replotted from Fig. 4D in Ref. 64 with the authors' permission.) (C) In naturally sleeping rats, depression of activity of the genioglossus muscle (GG) measured in arbitrary units (A.U.) during the period of REM sleep without muscle twitches (“TONIC”) occurred with a similar magnitude during continuous microperfusion of the XII nucleus region with strychnine and when the nucleus was perfused with a vehicle (Control). (Data extracted and re-plotted from Fig. 4 in Ref. 358 with the authors' permission.)