The hopping response after two-stage cortical ablation in young and adult rabbits

In a group of 14 rabbits aged between 14 and 21 days a hemidecortication was performed in the left hemisphere. A normal monopedal lateral hopping response developed in both forelegs. At adult age, 13 weeks after the first lesion, the remaining cortex on the right side was ablated. Three days afterwards the hopping response was tested again. In all animals, the hopping response remained positive in the right foreleg, contralateral to the lesioning at early age. However, in 10 out of 14 animals the response was absent on the left side, contralateral to the recent lesion. These results show that the hopping response is not mediated by corticofugal connections of the remaining hemisphere of the foreleg contralateral to the early lesion.