Behavioral recovery after transplantation into a rat model of Huntington'sdisease: Dependence on anatomical connectivity and extensive postoperativetraining

Rats were trained to perform a conditioned stimulus-response task known to be sensitive to striatal damage, after which they received unilateral excit otoxic striatal lesions. The subsequent implantation of graft tissue into t he lesioned striatum was either immediate (9 days) or substantially delayed (70 days). When retested 14 weeks later, all graft and lesion rats were eq ually impaired initially and biased their responding toward the ipsilateral side. Graft-associated recovery was evident with repeated postoperative te sting, but only in rats that had received transplants 9 days postlesion. It is suggested that this training-dependent. graft-associated recovery is me diated specifically by the restored host-graft connections.