ABSTRACT
This chapter proposes an integrative role for serotonin in the central nervous system. It shows that serotonin’s involvement in behavioral state control is a by-product of its more fundamental role in motor control and its integration with sensory information processing and autonomic regulation. An initial stage in a basic strategy for elucidating the behavioral and physiological roles of a brain neurochemical system might involve an examination of its response to a variety of intense conditions, especially those that are biologically and ecologically relevant. Rapid-eye-movement sleep is characterized by an inhibition of the motoneurons controlling anti-gravity muscle tone and a resulting paralysis. The activity of brain serotonergic neurons, regardless of the nuclei in which they are found, changes dramatically across the sleep/wake/arousal cycle. Serotonergic neurons play an auxiliary role in coordinating appropriate autonomic and neuroendocrine outputs to the ongoing tonic or repetitive motor activity.
