Effects of dopamine-rich grafts on conditioned rotation in rats with unilateral 6-hydroxydopamine lesions.

To assess the capacity of dopamine-rich grafts to ameliorate conditioned behavioural deficits induced by dopamine depleting lesions, rats with unilateral 6-hydroxydopamine lesions and intrastriatal grafts were compared with rats with lesions alone and with unoperated control rats in learning a conditioned turning response ('conditioned rotation') for water. The lesions impaired conditioned contralateral rotation and the grafts ameliorated the impairment. By contrast, the grafts introduced an ipsilateral impairment which was not apparent in the rats with lesions alone. The results show that some aspects of graft function are adaptive, but that other aspects of function are not well controlled by the host brain, and so may be maladaptive.