Functional aspects of the involvement of the hippocampus in behavior and memory functions.

In order to outline the involvement of the hippocampus in behavior and memory functions the results of grafting experiments in the hippocampal formation are presented in addition to former lesion and stimulation studies. Grafts of fetal hippocampal tissue were found to induce short-term beneficial effects on learning and memory. Functional efficiency of the grafts could be substantially improved by additional subcutaneous administration of carbachol over a period of 6 months. As carbachol does not cross the blood-brain barrier (BBB) due to its polar structure the data support the view that grafts of fetal neuronal tissue may induce a prolonged permeability of the BBB over a long period of time which could also be shown by HRP-histochemistry.