Can fetal neural transplants restore function in monkeys with lesion-induced behavioural deficits?

Experiments are now being conducted in monkeys to see whether the transplantation of fetal neural tissue, rich in certain neurotransmitter-producing cells, can restore behaviour in animals with movement or learning impairments induced by lesions that have destroyed important neurotransmitter pathways. Transplantation of dopamine neurons in humans may prove to be a useful therapy in Parkinson's disease, in which a severe movement disorder is associated with degeneration of the dopamine system. Transplantation of cholinergic neurones in monkeys can overcome a severe learning impairment induced by lesion of the cholinergic system. Cholinergic transplantation may eventually be of use in a variety of neurodegenerative dementing illnesses.