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. 2016 Jul 3;594(19):5391–5414. doi: 10.1113/JP271324

Figure 1. Anatomic representation of brain regions involved in the regulation of REM sleep and REM sleep atonia .

Figure 1

Sagittal representation of a rodent brain (left), with coronal views at three rostral–caudal levels (right, A–C). A zone within the medulla, specifically in the ventromedial medulla (VMM), is thought to play a key role in REM sleep atonia control. (1) The most rostral part of the VMM does not have a significant role in REM sleep atonia (Sastre et al. 1981; Lu et al. 2006). (2) The VMM near the inferior olive, near Magoun's inhibitory section, is the key zone for REM sleep atonia control (Magoun & Rhines, 1946; Kanamori et al. 1980; Chase et al. 1984; Schenkel & Siegel, 1989; Holmes & Jones, 1994; Lai & Siegel, 1997; Hajnik et al. 2000; Boissard et al. 2002; Morales et al. 2006; Sapin et al. 2009). (3) Caudal to the inhibitory zone, glutamatergic neurons regulate REM sleep atonia (Vetrivelan et al. 2009). Coronal views (A–C) show the zones of stimulation (continuous outlines) or lesion (dashed outlines) that either induce muscle atonia (stimulation) or decrease muscle atonia (lesion). (4) Lesions in the cat have targeted the VMM near the inferior olive (Holmes & Jones, 1994), while stimulation studies (6, 7) have also targeted the VMM as an atonia zone (Magoun & Rhines, 1946). Other studies, both lesion (5) studies (Schenkel & Siegel, 1989) and stimulation (8, 9) experiments (Takakusaki et al. 2001; Habaguchi et al. 2002) have targeted a more dorsal region just lateral to the midline, the caudal and dorsal extent of the nucleus gigantocellularis and nucleus magnocellularis or dorsal paragigantocellular region. In rats, both lesion (10) studies (Vetrivelan et al. 2009) and studies with electrical stimulation (11, 12) have targeted the ventromedial medulla as a key atonia zone (Lai and Siegel, 1988; Hajnik et al. 2000). Overall, despite the use of different methods and species, there is a significant overlap in the regions implicating the ventromedial medulla in atonia. Abbreviations: DpMe, deep mesencephalic reticular nucleus; Gi, gigantocellular nucleus; GiA, α gigantocellular nucleus; GiV, ventral gigantocellular nucleus; IO, inferior olive; LC, locus coeruleus; LDT, laterodorsal tegmental nucleus; LPT, lateral pontine tegmentum; py, pyramids; SLD, sublaterodorsal nucleus; SOM, supraolivary medulla; vlPAG, ventrolateral periaqueductal grey matter; VMM, ventromedial medulla; 7N, facial nucleus.