ABSTRACT
This chapter summarizes progress in the study of hypothalamic circuitry underlying sleep, especially recent work in which the immediate-early gene, c-fos, has been used to define neuronal populations related to behavioral state. Combining Fos immunohistochemistry with classical tract tracing techniques has proved to be a powerful approach that permits localization of state-dependent neurons as well as identification of their neurotransmitters and projections. Cholinergic neurons in the basal forebrain are implicated in waking and electroencephalogram (EEG) desynchronization. The basal forebrain includes the vertical and horizontal limbs of the diagonal band of Broca, the substantia inominata, and the magnocellular preoptic area where sleep-active cells have been identified. Electrical stimulation of the region containing the laterodorsal and pedunculo-pontine tegmental also drives cortical acetylcholine release and induces cortical desynchronization. Lesions of the basal forebrain produce slow waves in the EEG and also decrease cortical acetylcholine levels.
