Prefrontal contributions to relational encoding in amnestic mild cognitive impairment.
Prefrontal contributions to relational encoding in amnestic mild cognitive impairment.
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DOI：
10.1016/j.nicl.2016.01.008
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Giovanello KS
中科院分区：
文献类型：
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作者：
Foster CM;Addis DR;Ford JH;Kaufer DI;Burke JR;Browndyke JN;Welsh-Bohmer KA;Giovanello KS
关系记忆衰退是遗忘性轻度认知障碍（aMCI）的早期标志。情景记忆的形成依赖于两种记忆机制支持的关系处理，即生成和绑定。使用功能磁共振成像（fMRI）的神经影像学研究主要集中在被认为是由内侧颞叶功能障碍介导的结合缺陷上。在本研究中，前额叶对关系编码的贡献也通过fMRI通过参数化操纵词三联词编码过程中的生成需求来研究。被诊断为aMCI的参与者和健康对照者编码由一个类别词组成的词三联词，其中有一个、零个、一个或两个语义相关的例子。随着生成需求的增加（即2 - 1 - 0链接三联体），两组都招募了一组与单词三联体编码相关的核心区域，包括海马旁回、颞上回和顶叶上小叶。被诊断为aMCI的参与者也随着生成需求的增加而参数化地调动了包括额下回和额中回在内的几个额叶区域，而对照组参与者则没有表现出这种调节。虽然两组之间因生成需求而招募的区域有一些功能重叠，但aMCI参与者的额叶区域招募与较差的记忆表现一致，这可能代表了与阿尔茨海默病相关的一种神经效率低下的形式。本研究探讨了前额叶对aMCI中关系编码的贡献。受试者编码的词三联词根据语义相关性而变化。aMCI参与者在编码过程中调节额叶区域的活动。健康的对照组在额叶区域没有这种调节。aMCI组的调制与较差的记忆表现相关。
Relational memory declines are well documented as an early marker for amnestic mild cognitive impairment (aMCI). Episodic memory formation relies on relational processing supported by two mnemonic mechanisms, generation and binding. Neuroimaging studies using functional magnetic resonance imaging (fMRI) have primarily focused on binding deficits which are thought to be mediated by medial temporal lobe dysfunction. In this study, prefrontal contributions to relational encoding were also investigated using fMRI by parametrically manipulating generation demands during the encoding of word triads. Participants diagnosed with aMCI and healthy control subjects encoded word triads consisting of a category word with either, zero, one, or two semantically related exemplars. As the need to generate increased (i.e., two- to one- to zero-link triads), both groups recruited a core set of regions associated with the encoding of word triads including the parahippocampal gyrus, superior temporal gyrus, and superior parietal lobule. Participants diagnosed with aMCI also parametrically recruited several frontal regions including the inferior frontal gyrus and middle frontal gyrus as the need to generate increased, whereas the control participants did not show this modulation. While there is some functional overlap in regions recruited by generation demands between the groups, the recruitment of frontal regions in the aMCI participants coincides with worse memory performance, likely representing a form of neural inefficiency associated with Alzheimer's disease. This study investigated prefrontal contributions to relational encoding in aMCI. Subjects encoded word triads that were varied by semantic relatedness. aMCI participants modulated activity in frontal regions during encoding. Healthy controls showed no such modulation in frontal regions. Modulation in the aMCI group correlated with worse memory performance.