G. GARCIA-ALIAS, K. TRUONG, P. SHAH, H. ZHONG, R. R. ROY, V. R. EDGERTON;
Integrative Biol. & Physiol., UCLA, Los Angeles, CA
The corticospinal and rubrospinal tracts predominantly control skilled hand function. Injuries to these tracts impair grasping but not gross motor functions such as overground locomotion. The aim of the present study was to determine whether or not control via the reticulospinal tract could mediate skilled hand function after damage to both the corticospinal and rubrospinal tracts. Adult rats received a bilateral injury to the corticospinal tract at the level of the medullar pyramids and a bilateral ablation of the rubrospinal axons at C4. One group of rats received two injections of chondroitinase-ABC at C7 acutely after injury and then were trained daily for reaching and grasping rehabilitation beginning 7 days post-injury for 6 weeks (Chase group, n = 5). A second group of rats received analogous injections of ubiquitous penicillinase but did not undergo any training (Pen group, n = 5). Compared to rats in the Pen group, rats in the Chase group improved their reaching and grasping abilities over time and had an increased density of reticulospinal processes in both the normal and ectopic areas of the grey ventral matter of the caudal segments cervical spinal cord. Overground locomotion was mildly and similarly affected in both groups. The results indicate that after damage to spinal tracts controlling specific functions, other related spinal tracts can take over the role of those damaged tracts and promote task specific recovery.