Effects of pyramidal lesions on manipulatory movements in the dog. An ontogenetic approach.

The role of age in the recovery of motor functions following unilateral pyramidotomy was studied in groups of puppies operated on at the age of 1, 2, 3 and 5 mo. The animals were trained postoperatively to retrieve with their forepaw morsels of food from test devices varying in shape, diameter and depth. Groups of normal animals of similar ages were trained in parallel. In all age groups the motor impairment following pyramidotomy was proportional to the digital involvement in a given task. Furthermore, the performance of operated dogs was essentially similar in all age groups and no better recovery of function was observed in animals operated on at the age of 1 than at 5 mo. The results are discussed in view of conflicting data concerning the age related differences in the recovery of motor functions after destruction of the pyramidal system in various species.