Activation of neurotransplants in humans

Clinical studies report symptomatic benefit in most fetal neurotransplantat ion treated Parkinson's disease patients. The underlying mechanism is incom pletely explained. We investigated whether neural connections between host and transplanted tissue are established. Two Parkinson's disease patients w ith clinically excellent outcome after transplantation were studied with fu nctional magnetic resonance imaging. A repetitive motor task that provided robust stimulation in the contralateral putamen in volunteers activated gra ft bearing regions of putamen in patients. In response to contralateral mot or tasks, activation was recorded consistently in left putamen in patient 1 and in right putamen in patient 2. Functional magnetic resonance imaging s uggests that neuronal rewiring contributes to the functioning of neurotrans plants in vivo in humans. (C) 1999 Academic Press.