Changing Concepts of Mechanisms of Waking and Sleep States

Abstract

The last comprehensive reviews on the historical development of ideas on waking and sleep states were written by Moruzzi (1964, 1972) and Jouvet (1967) and dealt with experiments using electrical stimulation and electrolytic lesion techniques. Although newer, more powerful tools have been introduced in recent years for activating and destroying cellular aggregates, the concepts of the location of various brain “centers” involved in the genesis of waking and sleep states have not significantly changed since the late 1960s. What has changed is the view of neuronal mechanisms and interactions between different parts of the brain, mostly as a result of the introduction of new techniques allowing the recording of single cells in the behaving animal and, since 1980, the analysis of ionic conductances underlying intrinsic electroresponsive properties of neurons. We shall, of course, refer to earlier concepts, and we shall try to resurrect some of them from unjustified oblivion, especially when they have withstood experimental testing. But our main goal in this historical perspective and throughout this book is to examine critically the conclusions of older studies, couched in terms of large black boxes, with the more precise data gained by looking inside single cells and neuronal networks and by defining connectivities and transmitters. Our basic tenet is that the cellular approach furnishes the ultimate criterion to test hypotheses from studies conducted at more global levels.