Cholinergic involvement in control of REM sleep paralysis

Abstract

REM sleep, also known as dreaming sleep, is marked by intense cortical activation and absence of skeletal muscle tone, so-called REM sleep paralysis (atonia). It is commonly believed that REM sleep paralysis functions to prevent movement during vivid dreams. Indeed, REM sleep behaviour disorder – a neurological condition marked by violent dream enactment – results from loss of REM sleep paralysis. For the last 50 years, biologists have focused on the identification of brain mechanisms responsible for REM sleep. A majority of evidence suggests that a brainstem region known as the sublaterodorsal nucleus (SLD), also called the subcoeruleus, is important for REM sleep generation (Jouvet 1962). However, there is uncertainty concerning the chemical mechanisms by which the SLD triggers REM sleep phenomena. For example, some data suggest that cholinergic modulation of SLD cells underlies REM sleep generation, whereas, other data suggest that GABAergic disinhibition and glutamatergic excitation of SLD cells are critical for REM sleep control (Boissard et al. 2002; Lu et al. 2006). The recent study by Weng et al. (2014) provides a potentially new framework for understanding REM sleep control by showing that both cholinergic and glutamatergic processes operating within the SLD could be important for triggering REM sleep paralysis.