Field parcellation of the human hippocampus along the longitudinal axis

Abstract The primate hippocampus includes the dentate gyrus, cornu ammonis (CA), and subiculum. CA is subdivided into four fields (CA1-CA3, plus CA3h/hilus of the dentate gyrus). with specific pyramidal cell morphology and connections. Work in non-human mammals has shown that hippocampal connectivity is precisely patterned both in the laminar and longitudinal axes. One of the main handicaps in the study of neuropathological semiology in the human hippocampus is the lack of clear laminar and longitudinal borders. The aim of this study was to explore a histochemical segmentation of the adult human hippocampus, integrating field (medio-lateral), laminar, and antero-posterior longitudinal patterning. We provide criteria for field parcellation of the human hippocampus based on the use of Rph3a, PCP4, Chromogranin A and RGS-14 immunostaining. We also provide novel histological data about the composition of species-specific regions of the rostral and caudal ends of the human hippocampus. The data are given with stereotaxic coordinates along the longitudinal axis. This study provides novel insights for a detailed region-specific parcellation of the human hippocampus useful for human brain imaging and neuropathology.