[Importance of the hippocampus and parahippocampus with reference to normal and disordered memory function].

For decades there have been differing, partly controversial ideas concerning the function of the hippocampus. They were newly stimulated by the discovery of the widespread neocortical connexions of the adjacent parahippocampus, which itself is closely interconnected via its anterior part with the hippocampus. All theories have in common that they conceive these areas to be sites for the integration of complex information. However, some of the observations regarding their role in various memory functions are very contradictory. The present article gives a survey of the current state of knowledge concerning anatomy, physiology and pathophysiology of these cerebral areas. It appears that hippocampus and parahippocampus play a significant part in the regulation of selective attention and expectation. Thus they might also influence the process of comparison and valuation which modulates the access to neocortical associative information stores.