Role of wake inducing brain stem area on rapid eye movement sleep regulation in freely moving cats

Some of the characteristic symptoms associated with rapid eye movement (REM ) sleep are opposite to, while some apparently resemble, those of wakefulne ss. Therefore, it was hypothesised that the neurons present in the wakefuln ess inducing area(s) in the brain are likely to communicate with the REM sl eep related neurons. Brain stem neurons were classified based on their firi ng rates in relation to electrophysiological correlates associated with spo ntaneous sleep and wakefulness recorded from freely moving, normally behavi ng cats. Thereafter, the responses of those classified neurons to stimulati on of brain stem reticular wakefulness inducing area were studied. Results from 63 neurons showed that the wake inducing area affected 62% of the neur ons. Fifty-eight percent of the neurons which increased firing during wakef ulness, including the REM-OFF neurons, were excited, while 70% of the neuro ns which decreased firing during wakefulness, including the REM-ON neurons, were inhibited. These observations support our hypothesis and, along with their physiological significance, are discussed. (C) 2001 Elsevier Science Inc.