Chapter 47: Acetylcholine as a brain state modulator: triggering and long-term regulation of REM sleep

Abstract

Publisher Summary One of the major conceptual and empirical challenges confronting behavioral neurobiology is to develop theoretical models and experimental paradigms that will help to understand how single cells and their specific chemical signals come to be organized at the level of population ensembles in order to determine the global behavioral states of waking and sleep. To help meet this challenge, recent discoveries suggesting a role for acetylcholine containing neurons in both the triggering and long-term regulation of REM sleep offer inviting and instructive opportunities. It is the main purpose of this chapter to provide a detailed review of a recent and unexpected discovery: the long-term potentiation of REM sleep following the micro-injection of the cholinergic agonist carbachol into the cholinergic neuronal population of the peribrachial pontine tegmentum. Following a brief summary of the background of the cholinergic hypothesis of REM sleep generation and the current concept of the cellular nature of the REM sleep generator network, this chapter discusses the general neurobiology of the peribrachial area, and focus on its cholinergic neuronal sub-population as a prelude to a detailed account of the long-term REM sleep enhancement that follows the microinjection of carbachol into this zone. It discusses this finding in terms of a new, “cholinergic priming” hypothesis, which attributes the surprisingly long duration of the response to the setting in motion of an endogenous metabolic mechanism.