Audrain Sam, Gilmore Adrian W, Wilson Jenna M, Schacter Daniel L, Martin Alex
Section on Cognitive Neuropsychology, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
Section on Cognitive Neuropsychology, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892.
J Neurosci. 2022 Aug 17;42(33):6445-6452. doi: 10.1523/JNEUROSCI.0832-22.2022.
Mounting evidence suggests distinct functional contributions of the anterior and posterior hippocampus to autobiographical memory retrieval, but how these subregions function under different retrieval demands as memories age is not yet understood. Specifically, autobiographical memory retrieval is not a homogeneous process; rather, it is thought to consist of the following multiple stages: an early stage of memory construction and a later stage of detailed elaboration, which may differently engage the hippocampus over time. In the present study, we analyzed data from 40 participants (23 female/17 male) who constructed and overtly elaborated on recent and remote memories in response to picture cues in the fMRI scanner. We previously reported a temporal gradient in the posterior hippocampus during the elaboration period of autobiographical retrieval, with posterior hippocampal activation observed for recent but not remote time points. Here, we consider the previously unanalyzed construction stage of retrieval, where participants searched for and selected a memory. We found no evidence of a temporal gradient during memory construction, instead observing strong anterior hippocampus activity regardless of memory remoteness. Our findings suggest a unique contribution of the anterior hippocampus to the construction process of autobiographical retrieval over time. These findings highlight that retrieval processes, which have yet to be integrated with current models of systems consolidation, offer novel insights into hippocampal subregion function over time. Hippocampal contributions to autobiographical memory retrieval may depend on several distinct factors including memory age and the retrieval process engaged. We previously found that the contribution of the posterior hippocampus to detailed elaborative retrieval diminishes as memories age, with no reliable activation of the anterior hippocampus over time. Here, we report that consideration of the earlier "construction" period of retrieval, where participants search for and retrieve general aspects of the memory, yielded significant anterior hippocampus activation regardless of memory age. These results provide evidence for a unique contribution of the anterior hippocampus to the constructive process of autobiographical retrieval over time and suggest that component processes of retrieval should be integrated into models of systems consolidation.
越来越多的证据表明，海马体前后部对自传体记忆提取有着不同的功能贡献，但随着记忆的老化，这些亚区域在不同提取需求下如何发挥作用仍不清楚。具体而言，自传体记忆提取并非一个同质化的过程；相反，它被认为由以下多个阶段组成：记忆构建的早期阶段和详细阐述的后期阶段，随着时间的推移，这两个阶段可能会以不同的方式涉及海马体。在本研究中，我们分析了40名参与者（23名女性/17名男性）的数据，这些参与者在功能磁共振成像扫描仪中，根据图片线索构建并公开阐述近期和远期记忆。我们之前报告过，在自传体记忆提取的阐述阶段，海马体后部存在时间梯度，在近期而非远期时间点观察到海马体后部激活。在这里，我们考虑了之前未分析的提取构建阶段，即参与者搜索并选择记忆的阶段。我们发现在记忆构建过程中没有时间梯度的证据，相反，无论记忆的远近，都观察到海马体前部有强烈的活动。我们的研究结果表明，随着时间的推移，海马体前部对自传体记忆提取的构建过程有独特的贡献。这些发现凸显出，尚未与当前系统巩固模型相结合的提取过程，为海马体亚区域随时间的功能提供了新的见解。海马体对自传体记忆提取的贡献可能取决于几个不同的因素，包括记忆的年龄和所涉及的提取过程。我们之前发现，随着记忆的老化，海马体后部对详细阐述性提取的贡献会减少，海马体前部不会随时间可靠激活。在这里，我们报告称，考虑到提取的较早“构建”阶段，即参与者搜索并提取记忆的一般方面，无论记忆年龄如何，都会产生显著的海马体前部激活。这些结果为海马体前部随时间对自传体记忆提取的构建过程有独特贡献提供了证据，并表明提取的组成过程应纳入系统巩固模型。
