ABSTRACT
This chapter deals with an account of ponto-geniculo-occipital (PGO) waves, which have been interpreted as internal activation stimuli. The chemical mediators of PGO wave generation, like REM sleep, proved to be cholinergic and not aminergic. Helen Baghdoyan showed that the cholinergic triggering of REM with its PGO waves was most easily facilitated when the cholinergic agonist, carbachol, was injected into the pontine reticular formation. PGO waves were attenuated or completely absent and the neuronal discharge was markedly reduced in waking compared to REM. The idea that PGO waves were unique to REM was challenged early on by Adrian Morrison, who reasoned that they instead reflected the activation of a startle network. Michel Jouvet was persuaded that a single PGO wave might be a kind of REM unit, and his REM deprivation experiments revealed that the mean daily number of waves was conserved as evidenced by their payback in post-deprivation recovery REM.
