The hippocampus becomes topographically and functionally specialized along the longitudinal axis with development

The human hippocampus exhibits distinct genetic, cellular, and connectivity profiles along its anterior-posterior long-axis, resulting in a differential sensitivity to visuospatial information. Long-axis development, therefore, may contribute to developmental increases in visuospatial memory capacity. To test this, we developed and applied a precision functional mapping technique to identify functional systems in the hippocampus of single subjects using BOLD-fMRI (N = 471, aged 5-21). We discovered considerable developmental remodeling of the hippocampal long-axis, particularly for the posterior functional system. With age, surface-area (mm²) of the posterior system decreased by 39.4%, while BOLD activity became increasingly independent and showed a sharper topographic boundary with the rest of the hippocampus. Notably, the posterior system showed strong preferential connectivity with medial-parietal regions which correlated with both age and age-adjusted memory scores. These results indicate the hippocampal long-axis becomes topographically and functionally specialized with development, potentially contributing to developmental increases in memory capacity.