Prolonged electrophysiological maturation of transplanted hippocampal neurons

The CA1 region of the rat hippocampal formation was lesioned by transient forebrain ischemia and subsequently repopulated with dispersed fetal hippocampal neurons. Using the hippocampal slice preparation, 7-12 months post-transplantation, intracellular recordings were made during synaptic activation and extracellular calcium measurements were made during iontophoretic application of excitatory amino acids. The data indicate that the developmental period of the transplanted neurons is prolonged with respect to N-methyl-D-aspartate (NMDA) receptor-mediated responses and may be involved in maintaining calcium dependent developmental processes such as fiber outgrowth.