Intracellular analysis of trigeminal motoneuron activity during sleep in the cat.

Intracellular recordings were made from trigeminal motoneurons of normally respiring, unanesthetized cats during naturally occurring sleep. The transition from quiet to active sleep was accompanied by tonic motoneuron hyperpolarization. Stimulation of the reticular formation induced a depolarizing potential in trigeminal motoneurons during quiet sleep and a hyperpolarizing potential during active sleep. The results provide a synaptic explanation for the phenomenon of reticular response reversal and insights into the basic mechanisms controlling motor activity during the sleep states.