Electrophysiological demonstration of host cortical inputs to striatal grafts.

Adult rats received a unilateral injection of ibotenic acid into the striatum, resulting in an extensive loss of intrinsic striatal neurones. Transplanted striatal cells from embryonic day 14 rat foetuses grew well in the damaged tissue and approximately 6 months later brain slices were cut in such a way as to include the grafts and nearby cortical tissue. Electrophysiological recordings from the grafts showed typical extracellular responses to stimulation of the subcortical white matter. Thresholds and latencies for responses were similar in grafted and control striatum. The grafted cells, however, appeared to be subject to less collateral inhibitory control than normal striatal neurones. The similarities between the responses of grafted neurones and those in normal striatum suggest that corticostriatal connections reform after transplantation, which may be an important component in the behavioural recovery observed in similar animals.