The posterior hippocampus becomes topographically and functionally specialized with development

The human hippocampus exhibits distinct genetic, cellular, and connectivity profiles along its anterior–posterior axis, promoting a long-axis specialization of function. In the posterior hippocampus, anatomical and effective/functional connectivity with medial parieto-occipital cortex promotes a specialization for encoding salient visuospatial information. Development of this system, therefore, may refine visuospatial memory encoding abilities. Recently, precision functional mapping techniques have indicated that the spatial topography of functional systems in the cortex is highly sensitive to individual variation related to developmental processes. With this in mind, we developed and applied a technique mapping functional systems in the hippocampus of single subjects using BOLD-fMRI ( N  = 471, aged 5–21 years). We discovered considerable developmental remodeling of the posterior hippocampal system. With age, the surface-area (mm ² ) of tissue dedicated to this system decreases by 39.4%, while BOLD activity becomes increasingly independent and shows a sharper topographic boundary with the rest of the hippocampus. Moreover, the posterior hippocampus shows preferential connectivity to a posteromedial network (particularly in the parieto-occipital sulcus), and strengthening of this connectivity is associated with both age and age-adjusted memory scores. These results indicate that the posterior hippocampus becomes topographically and functionally specialized with development, potentially contributing to developmental increases in memory capacity.