Hippocampal circuit alterations that differentially affect hippocampal subfields are associated with age‐related memory decline. Additionally, functional organization along the longitudinal axis of the hippocampus has revealed distinctions between anterior and posterior (A‐P) connectivity. Here, we examined the functional connectivity (FC) differences between young and older adults at high‐resolution within the medial temporal lobe network (entorhinal, perirhinal, and parahippocampal cortices), allowing us to explore how hippocampal subfield connectivity across the longitudinal axis of the hippocampus changes with age. Overall, we found reliably greater connectivity for younger adults than older adults between the hippocampus and parahippocampal cortex (PHC) and perirhinal cortex (PRC). This drop in functional connectivity was more pronounced in the anterior regions of the hippocampus than the posterior ones, consistent for each of the hippocampal subfields. Further, intra‐hippocampal connectivity also reflected an age‐related decrease in functional connectivity within the anterior hippocampus in older adults that was offset by an increase in posterior hippocampal functional connectivity. Interestingly, the anterior–posterior dysfunction in older adults between hippocampus and PHC was predictive of lure discrimination performance on the Mnemonic similarity task (MST), suggesting a role in memory performance. While age‐related dysfunction within the hippocampal subfields has been well‐documented, these results suggest that the age‐related dysfunction in hippocampal connectivity across the longitudinal axis may also contribute significantly to memory decline in older adults.

中文翻译：

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沿海马体及其子区域纵轴的功能连接发生与年龄相关的变化。


对海马子区域有不同影响的海马回路改变与年龄相关的记忆力下降有关。此外，沿海马纵轴的功能组织揭示了前部和后部（A-P）连接之间的区别。在这里，我们以高分辨率检查了年轻人和老年人内侧颞叶网络（内嗅、嗅周和海马旁皮质）内的功能连接（FC）差异，使我们能够探索海马亚区如何跨颞叶纵轴连接。海马体随着年龄的增长而变化。总体而言，我们发现年轻人的海马体与海马旁皮层（PHC）和鼻周皮层（PRC）之间的连接确实比老年人更紧密。这种功能连接的下降在海马前部区域比后部区域更为明显，这对于每个海马亚区都是一致的。此外，海马内连接性还反映出老年人前海马内功能连接性与年龄相关的下降，而后海马功能连接性的增加抵消了这一下降。有趣的是，老年人海马体和 PHC 之间的前后功能障碍可以预测助记符相似性任务 (MST) 上的诱饵辨别表现，表明在记忆表现中发挥作用。虽然海马亚区内与年龄相关的功能障碍已得到充分记录，但这些结果表明，与年龄相关的海马纵轴连接功能障碍也可能显着导致老年人的记忆力下降。