Cellular Mechanisms and Neural Circuits That Produce Sleep

Abstract

Recently developed techniques in electrophysiology have yielded new insights into the cellular mechanisms that produce EEG synchrony and sleep. These advances include the use of the brain slice preparation in which a slice of brain tissue about 400 μm thick is placed in a medium that provides the necessary oxygen and nutrients to maintain cell viability for a day or more. These cells are devoid of most of their afferent influences, and their intrinsic properties can be studied with intracellular electrodes. Moreover, the bath medium and intracellular contents can be manipulated to investigate the roles of various neurotransmitters, receptor types, and their associated ion channels. This has been accomplished by the addition to the bath medium of specific receptor blockers, enzymes that break down and inactivate certain neurotransmitters, and altered concentrations of ions such as sodium, potassium, chloride, and calcium. The brain slice preparation has contributed much to our understanding of the cellular mechanisms that underlie the EEG recordings taken from intact subjects during sleep and waking.