[Neuronal activity specific to paradoxical sleep in the bulbar reticular formation in the unrestrained cat]

Single units were recorded in the bulbar reticular formation (BRF) of unrestrained, freely behaving Cats. In the ventromedial part of the BRF (n. reticularis magnocellularis, Mc) corresponding to the "bulbar inhibitory center", we have found a cluster of cells showing tonic activation highly selective to paradoxical sleep (PS). Furthermore, we have confirmed the presence of the same type of cells in the dorsomedial part of the BRF which corresponds to the medial part of the n. reticularis parvocellularis (Pc). The functional significance of these two groups of cells is discussed in terms of the postural atonia and the atonia of jaw closer muscles observed during PS.