FACTORS INFLUENCING EXTENSOR TONUS AND RESPIRATION IN DECEREBRATE CATS

Abstract

IN THE process of decerebrating a number of cats, it was noticed that there was considerable variation in the degree of extensor tonus which developed. With continued practice and standardization of the operative technique, the variability in the immediate postoperative period was made very slight. However, in animals observed an hour or more after operation, the degree of extensor tonus varied tremendously from one cat to another. Moreover, in any one cat there were usually transitory, but very marked, changes in tonus which could not be readily explained by means of known reflex patterns. In one of the decerebrate cats a Cheyne-Stokes type of breathing developed. During periods of apnea the extensor tonus was slight to moderate, and during periods of breathing the cat went into pronounced opisthotonos. This suggested that factors which were capable of influencing respiration might also influence extensor tonus. The purpose of the present paper is