A Number of Recent Reviews Provide Detailed Descriptions of the Organization of the Neu- Rologic Substrates Controlling Sleep-wake

673 A NUMBER OF RECENT REVIEWS PROVIDE DETAILED DESCRIPTIONS OF THE ORGANIZATION OF THE NEUROLOGIC SUBSTRATES CONTROLLING SLEEP-WAKE systems.1-6 The reader is also referred to an extensive consideration of rapid eye movement (REM) sleep.7 Our recent minireview focused on developmental events related to the decrease in REM sleep, including its relationship to other developmental changes, the role of blood flow, some factors that may influence its progress, and its potential role in brain development.8 Briefly, the part of the brain controlling sleep-wake states and most responsible for inducing REM sleep is the reticular activating system (RAS), especially its cholinergic component. The RAS triggers changes in state mainly via its ascending projections to the intralaminar thalamus (ILT) to modulate thalamocortical systems in both waking and REM sleep, while simultaneously modulating REM sleep and postural muscle tone via its descending projections to the pontomedullary reticular formation. Since that review, a more complete survey of the transmitter systems that affect these neurons has been completed, and the role of electrical coupling as a novel mechanism in sleep-wake control has been discovered. We will describe the organization of sleep-wake control systems in the adult and then deal with development.