Motor recovery after serial spinal cord lesions of defined descending pathways in cats.

The food-taking movement by which a cat uses its forepaw to take a piece of food and bring it to its mouth normally depends on the cortico- (CS) and rubrospinal (RS) tracts and disappears when they are transected in C5; a slow reappearance over months is due to bulbospinal (BS) take-over. After complete CS transection but minimal RS transection, food-taking remains. If, one month later, the RS tract is completely transected, food-taking is not abolished as it is when transection is made in one session. It is permanently abolished after a third transection of the ventral quadrant in C2. It is suggested that the food-taking remaining after the first lesion is due to combined RS and BS activity and that the RS tract induces the BS neurones to contribute to the extent that they can take over when the RS tract is completely transected.