Respiratory and Postural Suppression by Stimulation of the Midpontine Dorsal Tegmentum in Decerebrate Cats

Abstract

In acute precollicular-postmammillary decerebrate cats, stimulation of the dorsal part of the caudal tegmental field (DTF) in the pons results in the parallel suppression of postural tone and respiration.1 Tonic discharges of bilateral hindlimb antigravity muscles are suppressed by DTF stimulation, and the animal becomes unable to stand upright (postural atonia). DTF stimulation also depresses diaphragmatic activity, leading to apnea for more than 20 seconds in some animals. In addition, DTF stimulation suppresses the tonic and rhythmic discharges of the external intercostal muscles2 and of the hypoglossal nerve innervating the genioglossus muscle.3 Previous studies4, 5 raise the possibility that DTF-elicited suppression of postural tone and respiration may result from activation of the descending axons passing through the DTF. All these findings lead us to believe that the descending inhibitory system activated by DTF stimulation may be involved in generalized motor suppression similar to the spontaneous suppression that occurs during sleep, especially during REM sleep.