Respiratory activity and sleep--wakefulness in the deafferented, paralyzed cat

The purpose of this study was to assess the role, if any, that peripheral feedback plays in the distinct respiratory patterns which are characteristic of the various states of consciousness. Those states include wakefulness, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep. Eight adult cats, implanted with electrodes and skull bolts for sleep recordings and head restraint, sustained extensive deafferentations (bilateral vagotomy and pneumothorax, spinal transection at T-1 level, bilateral section of the phrenic nerves), were paralyzed with gallamine, artificially ventilated (ensuring stable blood gases), and held at a constant temperature. Central respiratory activity was determined by phrenic nerve recordings. During NREM sleep, respiratory activity slowed as in intact cats. During REM sleep without phasic events, phrenic activity did not differ from that in NREM sleep. During REM sleep with phasic phenomena, fast and irregular "breathing" was observed. It is concluded that states of consciousness have a direct effect on central respiratory activity. Possible mechanisms for this effect are discussed.