Role of medullary reticular neurons in the inhibition of trigeminal motoneurons during active sleep.
We sought to identify those cells involved in the generation of atonia of the masseter muscles during active sleep. A neuronal population was examined in the medullary reticular formation which has been shown to project monosynaptically to trigeminal motoneurons and provide inhibitory input to them. These neurons exhibited a pattern of state-dependent discharge which was characterized by a tonic increase in firing frequency which paralleled the tonic decrease in somatomotor reflex activity (within the trigeminal system) in the continuum of wakefulness to quiet (NREM) sleep to active sleep. This population of cells discharged at extremely high rates during active sleep, especially during periods of rapid eye movements, when postsynaptic inhibitory control of motoneurons is most prominent. We therefore suggest that these medullary units are the inhibitory neurons which are responsible for the postsynaptic inhibition of trigeminal motoneurons during active sleep.
D000818:Animals; D002415:Cats; D004569:Electroencephalography; D008526:Medulla Oblongata; D009046:Motor Neurons / Q000502:physiology*; D009433:Neural Inhibition; D009474:Neurons / Q000502:physiology; D012154:Reticular Formation / Q000166:cytology / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D014276:Trigeminal Nerve / Q000502:physiology*