Aging and exercise have opposing effects on mnemonic discrimination task performance, which putatively taxes pattern separation mechanisms reliant on the dentate gyrus (DG) subfield of the hippocampus. In young adults, increasing cardiorespiratory fitness (CRF) has been shown to improve mnemonic discrimination task performance and increase left anterior DG/CA3 volume. It is unknown how these variables interact in cognitive aging, yet this knowledge is critical, given the established effects of aging on hippocampal plasticity. To investigate these relationships, 65 older adults (aged 55–85 years) completed a submaximal treadmill test to estimate CRF, a mnemonic discrimination task, and a high‐resolution MRI scan to determine hippocampal subfield volumes. Our older adult sample demonstrated the lowest task accuracy in the condition with the greatest stimuli similarity and left DG/CA3 body volume significantly predicted accuracy in this condition. Our results did not provide support for relationships between CRF and task accuracy or CRF and DG/CA3 volume as evidenced in studies of young adults. Instead, CRF predicted bilateral subiculum volume in older adult women, not men. Altogether, these findings provide further support for a role of the DG in behavioral pattern separation in humans and suggest that CRF may have differential effects on hippocampal subfield integrity in older adult men and women. ClinicalTrials.gov identifiers: (a) Neuroimaging Study of Exercise and Memory Function, NCT02057354; (b) The Entorhinal Cortex and Aerobic Exercise in Aging, NCT02775760; (c) Physical Activity and Cognition Study, NCT02773121.

中文翻译：

---

心肺健康、海马亚区体积和记忆力辨别任务在衰老中的表现

衰老和运动对记忆辨别任务的表现有相反的影响，这可能对依赖于海马齿状回 (DG) 子区域的模式分离机制征税。在年轻人中，增加心肺健康 (CRF) 已被证明可以提高记忆辨别任务的表现并增加左前 DG/CA3 体积。目前尚不清楚这些变量如何在认知衰老中相互作用，但鉴于衰老对海马可塑性的既定影响，这一知识至关重要。为了研究这些关系，65 名老年人（55-85 岁）完成了一项次最大量的跑步机测试以估计 CRF、一项记忆识别任务和一项高分辨率 MRI 扫描以确定海马亚区体积。我们的老年人样本在具有最大刺激相似性的情况下表现出最低的任务准确性，并且左侧 DG/CA3 体量显着预测了这种情况下的准确性。我们的结果并未支持 CRF 与任务准确性或 CRF 与 DG/CA3 体积之间的关系，正如对年轻人的研究所证明的那样。相反，CRF 预测的是老年女性而非男性的双侧下托体积。总而言之，这些发现进一步支持了 DG 在人类行为模式分离中的作用，并表明 CRF 可能对老年男性和女性的海马亚区完整性有不同的影响。ClinicalTrials.gov 标识符：(a) 运动和记忆功能的神经影像学研究，NCT02057354；(b) 衰老中的内嗅皮层和有氧运动，NCT02775760；