Functional decerebration in the cat

Abstract

A comparison is made between vascular and ultrasonic methods for producing a functional decerebrate cat for pharmacological and physiological studies. In 35 cats anemic decerebration was produced by means of circulatory interference and in 55 cats transection of the midbrain was accomplished by means of ultrasound. Methods of circulatory interference always included ligating the basilar artery above the origin of the inferior posterior cerebellar artery and then one of the following procedures: (1) permanent occlusion of the common carotid arteries; (2) temporary occlusion of the same; or (3) temporary occlusion of branches of the carotid bifurcation. A single unfocused ultrasound beam of 5 watts/ cm2 for 60 sec. was used on the midbrain. Whereas anemic decerebration was not reliable in making chronic decerebrate preparations (not irreversible or eventually dying due to brain edema) ultrasonic irradiation of the midbrain proved to be a simple, reliable and rapid means for the routine preparation of bloodless decerebrate cats. Functional characteristics of decerebration were (1) the absence of volitional activity, (2) extensor rigidity, (3) the elicitability of tonic and labyrinthine postural reflexes, and (4) the lack of temperature. The functional integrity of descending pathways from the hypothalamus concerned in vasomotor and respiratory control, both before and after exposure to ultrasound,were also evaluated.