The current volumes of The Hippocampus reflect the prodigious amount of work aimed at discovering the functions of this structure over the past decade. The hippocampus ideally lends itself to two types of study: (1) because of its regular and relatively simple cytoarchitecture, it can serve as a model for cortical processing in general, and (2) because of its size and central location, the role of the hippocampus in the total ecology of brain function poses an important challenge. We attempted to divide the contributions to Volumes 3 and 4 according to these two types of experimental aims. As...