Spontaneous and centrally induced behaviors in normal and thalamic opossums.

Abstract

Electrical stimulation of localized areas of the opossum [Didelphis marsupialis virginiana] medulla and cerebellum induced goal-oriented eating and grooming behaviors or stereotyped gagging. Following radical telencephalic lesions, these animals showed considerable behavioral capacity and in many cases continued to demonstrate centrally induced responses. Animals with lesions, however, failed to groom or show active food-seeking behavior, and they showed poor thermoregulation in the heat, presumably because of the loss of thermoregulatory grooming. These deficits following removal of the telencephalon may have resulted from disruption of important sources of control over behaviors rather than from loss of basic consummatory response mechanisms, since grooming and eating, while less directed, could be still be elicited by central stimulation. These results support the view that the lower brain stem may contain intrinsic neural circuits for the integration of complex behaviors.