Effects of the stimulation of paleocerebellum on certain vegetative functions in the cat

Abstract

Effects of the stimulation of the cerebellar vermis on some vegetative functions and the electrical activity of limbic and other regions of the brain were studied in anaesthetized cats as well as in unanaesthetized cats restrained with Flaxedil. The results indicate that different lobules of the vermis were not uniformly responsive in producing the autonomic effects. Lobules located more anteriorly in the vermis were more responsive than those located posteriorly. In the anaesthetized preparations the preponderance was that of depressor responses and respiratory inhibition, whereas in the unanaesthetized preparations, mostly pressor responses were obtained on stimulation of the vermian cortex. Similarly in the anaesthetized animals, pupillary changes or intravesical pressure changes were not conspicuous. On the other hand, marked but variable effects on the intravesical pressures and the pupillary changes were obtained on stimulation of the vermian cortex in the unanaesthetized preparations. An analysis of the results obtained in this study does not permit the parcellation of the cerebellar vermis into anterior sympathicotonic or posterior arasympathicotonic regions. Instead, it is suggested that the fibre pathways involved in producing these responses of cerebellar stimulation can be more fruitfully analysed by correlating the neuraxial hierarchy with the complexity or type of autonomic activity pattern. Desynchronization of the electrical activity of various brain regions was an invariable accompaniment of cerebellar stimulation regardless of the autonomic activity pattern obtained on this stimulation. In a number of animals stimulation of the anterior cerebellum produced responses of sexual organs, namely penile erections or twitchings at the vaginal opening. In a pregnant cat stimulation of the vermis produced marked contractions of the gravid uterus.