The hippocampus and space revisited

The hippocampal formation has long been the focus of in-tense interest among neuroscientists. The discovery by Sco-ville and Milner (1957) that the mesial temporal lobe, includ-ing the hippocampal formation, played a central role in memory function in humans can be said to have started the modern era of research on this brain system. There followed two decades of animal research aimed at creating experi-mental models of the memory defects observed in humans, including my dissertation research, which met with scant suc-cess (Nadel, 1968). Indeed, when John O’Keefe and I started considering the hippocampus and its possible role in spatial mapping several years later, one of our greatest challenges was to analyze the extant lesion literature in terms of this theory with the minimum amount of special pleading. There were already several hundred such studies, varying exten-