Organization of Hippocampal Neurons and Their Interconnections

In his famous work, Ramon y Cajal (1911) has a drawing of the main connections of the hippocampal formation (Fig. 1). This is indeed a remarkable figure. With few exceptions, further investigations with different techniques have shown Ramon y Cajal to be correct, despite the fact that he had to infer the direction of impulse traffic from histological data only. Physiological and biochemical techniques have, however, added details in the scheme devised by Ramon y Cajal, and changed it on some points. The purpose of this chapter is to give a review of what these studies have added to our knowledge about hippocampal neuronal organization.