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 wakefulness. Therefore, it was hypothesised that the neurons present in the wakefulness inducing area(s) in the brain are likely to communicate with the REM sleep related neurons. Brain stem neurons were classified based on their firing rates in relation to electrophysiological correlates associated with spontaneous sleep and wakefulness recorded from freely moving, normally behaving cats. Thereafter, the responses of those classified neurons to stimulation of brain stem reticular wakefulness inducing area were studied. Results from 63 neurons showed that the wake inducing area affected 62% of the neurons. Fifty-eight percent of the neurons which increased firing during wakefulness, including the REM-OFF neurons, were excited, while 70% of the neurons 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.