Functional map of left human hippocampus

The hippocampus' organization is very well known from the cytoarchitecture perspective but its functional integrity is less understood in humans. In this study, left hippocampal differentiation along the longitudinal axis was defined based on task-based functional connectivity, resting-state functional connectivity, and structural covariance connectivity. The resulting hippocampal parcels were then characterized based on two multimodal functional connectivity and a quantitative analysis of associated behavioral functions. Analyzing the parcels across purely functional large-scale connectivity revealed an organization of the hippocampus that mirrored the tripartite functional differentiation with a head, body and tail subdivision. At higher subdivision levels, the hippocampus was additionally divided into robust 5 and 7 subregions along the longitudinal dimension. In contrast, the organization of the hippocampus based on structural data mirrored a hybrid like differentiation with a head parcel and two additional medial and lateral subregions in the medial-lateral dimension reminiscent of the cornu ammonis and subiculum subfields. Behavioral profiling of the functional organization indicated a behavioral gradient from anterior to posterior representing emotion-cognition and self-centric vs. world centric information processing.