Shifts in intrinsic neural timescale of hippocampus support the maturation of inhibitory control and working memory in youth

The intrinsic neural timescale (INT) provides temporal windows in brain activity that process information of different durations, crucial for the integration and segregation of external inputs and ultimately shaping cognition and behavior. Recent research has uncovered a pronounced INT hierarchy along the adult hippocampus's long-axis. Yet, the development of INT organization within the hippocampus—particularly the pattern of its hierarchical structure and its impact on cognitive development—has not been thoroughly investigated in youth. Here, we discovered that the INT distribution in youth presents a distinct hierarchical structure along both posterior-anterior and proximal-distal axes of the hippocampus. Strikingly, this hierarchical structure correlates significantly with the first principal gradient of the hippocampal-cortical functional connectome and the thickness of hippocampal grey matter. Furthermore, we observed notable changes in the hippocampal INT landscape during youth, characterized by a general narrowing of timescales, alongside dedifferentiation along the hippocampal organizational axes. These maturational changes significantly link to improvements in inhibitory control and working memory performance. Collectively, our findings reveal the developmental patterns of temporal integration and segregation hierarchies within hippocampus, and highlights the profound significance of INT as a neural underpinning that orchestrates cognitive growth. •We found a unique hierarchical structure of intrinsic neural timescales (INT) along two axes of the hippocampus in youth.•Hippocampal INT hierarchy links to both the hippocampal-cortical functional connectome and grey matter thickness.•Hippocampal INT showed significant narrowing, and dedifferentiation along its organizational axes in youth.•Changes in the INT are significantly linked to improvements in inhibitory control and working memory.