Abstract
Unilateral transection of the bulbar pyramid, performed before the ablation of the ipsilateral sensorimotor cortex, has been shown to facilitate the recovery of operantly conditioned reflexes and compensatory processes in rats. Such enhanced behaviorai recovery was absent when only the sensorimotor cortex was ablated. This phenomenon is explained by the switching of motor activity under the control of the cortico-rubrospinal system. Switching of the descending influences is accomplished through the following loop: cortico-rubrai projectionred nucleus-inferior olive-cerebellum-thalamuscerebral cortex. This suggests that a preliminary lesion of the peripheral part of the system, represented by a descending spinal projection, facilitates the recovery processes to develop during the subsequent destruction of its central part.