Individual differences in associative memory among older adults explained by hippocampal subfield structure and function
Individual differences in associative memory among older adults explained by hippocampal subfield structure and function
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DOI：
10.1073/pnas.1713308114
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发表时间：
2017-11-07
影响因子：
11.1
通讯作者：
Wagner, Anthony D.
中科院分区：
文献类型：
--
作者：
Carr, Valerie A.;Bernstein, Jeffrey D.;Wagner, Anthony D.
老年人经历情节记忆障碍，从轻度到临床显著。鉴于内侧颞叶（MTL）在情景记忆中的关键作用，MTL结构和功能的年龄相关变化可能部分解释了记忆的个体差异。使用超高场7 T结构MRI和高分辨率3 T功能MRI（hr-fMRI），我们评估了代表认知健康谱的老年人MTL子场厚度和功能。参与者在hr-fMRI中进行了一项联想记忆任务，他们编码并随后检索了面孔-名称对。受先前研究的启发，我们假设性能差异可通过以下因素解释：（i）内嗅皮层（ERC）和CA 1顶神经层[CA 1-放射层陷窝分子（SRLM）]厚度，以及（ii）ERC和齿状回（DG）/CA 3区域的活性。回归分析表明，这些因素的组合显着占内存性能的变化。在这些指标中，CA 1-SRLM厚度与记忆呈正相关，而DG/CA 3检索活动与记忆呈负相关。此外，在同一模型中包括结构和功能指标比单模态模型更好地解释了性能。这些结果促进了对MTL子字段结构和功能的独立但收敛影响如何有助于与年龄相关的记忆障碍的理解，补充了啮齿动物和人类尸检文献中的发现。
Older adults experience impairments in episodic memory, ranging from mild to clinically significant. Given the critical role of the medial temporal lobe (MTL) in episodic memory, age-related changes in MTL structure and function may partially account for individual differences in memory. Using ultra-high-field 7T structural MRI and high-resolution 3T functional MRI (hr-fMRI), we evaluated MTL subfield thickness and function in older adults representing a spectrum of cognitive health. Participants performed an associative memory task during hr-fMRI in which they encoded and later retrieved face-name pairs. Motivated by prior research, we hypothesized that differences in performance would be explained by the following: (i) entorhinal cortex (ERC) and CA1 apical neuropil layer [CA1-stratum radiatum lacunosum moleculare (SRLM)] thickness, and (ii) activity in ERC and the dentate gyrus (DG)/CA3 region. Regression analyses revealed that this combination of factors significantly accounted for variability in memory performance. Among these metrics, CA1-SRLM thickness was positively associated with memory, whereas DG/CA3 retrieval activity was negatively associated with memory. Furthermore, including structural and functional metrics in the same model better accounted for performance than did single-modality models. These results advance the understanding of how independent but converging influences of both MTL subfield structure and function contribute to age-related memory impairment, complementing findings in the rodent and human postmortem literatures.