Furthermore, this definition corresponds well with the available behavioral evidence. This approach allows us to provide a precise definition of these zones as an alternative to the more arbitrary reference to dorsal and ventral hippocampus that is common in the literature. We review recently published data on CA1 ( Dong et al., 2009) and CA3 (Thompson et al., 2009) and add a similar analysis of dentate gyrus. An intermediate region that has only partly overlapping characteristics with its neighbors separates the two. We argue that the hippocampus can be thought of as a set of separate structures with a rostral/dorsal zone that serves the cold cognitive function and a caudal/ventral zone that corresponds to the hot/affective hippocampus. However, gene expression and anatomical projections patterns that vary along the rostral/caudal-dorsal/ventral extent of the hippocampus suggest that it can be divided into separate structures or zones. The thesis of this brief review is that there is sufficient behavioral evidence indicating the existence of both functions within the hippocampus. But the literature also shows another side to the hippocampus, a hot hippocampus that is intimately tied to emotion, regulates stress responses and whose dysfunction leads to affective disorders such as depression.
According to this view, hippocampal dysfunction leads to a “pure” amnesia. There is the cold cognitive hippocampus that stands as the gate to declarative memories, regardless of their emotional content or lack thereof. Despite over 50 years of research, attention and debate, there is still controversy over the basic general function of the hippocampus.