COORDINATED EYE AND BODY MOVEMENTS EVOKED BY BRAINSTEM STIMULATION IN DECEREBRATED CATS

Abstract

Conjugate ocular deviations were elicited by electrical stimulation of 1/3 of 2000 sites distributed from posterior diencephalon to medulla; corrdinated movements of back or limbs were obtained from only 1/5 of all sites. Torsional conjugate deviations, usually without body movements, were obtained from stimulation in the region of the zona incerta and pretectal area. Contralateral conjugate deviations, usually with upward components, were evoked from the dorsal midbrain; sites in the superior colliculus yielded no body movements while many stimulations of the underlying tegmentum yielded body as well as ocular movements. Stimulation of sites in the postero-ventral midbrain and anterior pontine tegmentum, and in the dorsal tegmentum of the medulla, yielded horizontal ipsilateral conjugate deviations, with few body movements. From the ventral tegmentum of the medulla, centering of the eyes was the predominant response. The general pattern of ocular movements obtained in the decerebrated cat resembles that in the feline encephale isole; significant differences in the two preparations were found on stimulation of the superior colliculus, the tegmentum of the ventral midbrain, and that of the ventral medulla.