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. Kember et al. map the precise boundaries of functional systems in the hippocampus using fMRI in a large-scale cohort. They find developmental changes in topographic organization along the anterior–posterior axis relevant to memory development.