Changes in the cerebello-cerebral response in the parietal cortex following ablation of the motor cortex in the cat: early occurrence and persistence

Abstract

To elucidate the compensatory mechanism which begins to work soon after damage to the brain, changes in the cerebeliar-induced cerebral cortical response in the parietal association cortex after ablation of the frontal motor cortex were studied in the cat. Stimulation of the interpositus or the lateral nucleus of the cerebellum before decortication, as reported in intact animals, induced two distinct types of response in the frontal motor and parietal association cortices respectively. The response in the frontal cortex was a sequential occurrence of a surface positive-depth negative (sP-dN) wave and a surface negative-depth positive (sN-dP) wave, and the response in the parietal cortex was mainly an sN-dP wave. In a small proportion of animals, the latter wave was preceded by a small sP-dN wave or a small dN wave without an sP wave. Ablation of the frontal motor cortex induced in the majority of animals a marked change in the cerebello-parietal cortical response, i.e. the occurrence of a new sP-dN wave preceding the sN-dP wave or enhancement of the pre-existing small dN wave, resulting in the parietal cortical response similar to the frontal cortical response of intact animals. The earliest post-lesion time observed for the occurrence of change was less than 1 hour, whereas its persistence was confirmed up to 213 days post-lesion.