Temporal association tracts and the breakdown of episodic memory in mild cognitive impairment
Temporal association tracts and the breakdown of episodic memory in mild cognitive impairment
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DOI：
10.1212/wnl.0b013e31827689e8
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发表时间：
2012-12-01
期刊：
影响因子：
9.9
通讯作者：
O'Sullivan, Michael J.
中科院分区：
文献类型：
--
作者：
Metzler-Baddeley, Claudia;Hunt, Sarah;O'Sullivan, Michael J.
目的：探讨轻度认知障碍（MCI）的核心特征——情景记忆的破裂与颞叶连接微结构的关系模式。方法：对25例轻度认知障碍患者和20例对照组进行弥散性MRI和认知评估。通过神经束造影重建了穹窿、海马旁扣带和钩侧束3条颞神经通路。组织体积分数——一种特定的萎缩测量方法——和显微结构测量方法对每个束进行了推导。为了测试关联的特异性，比较束（皮质脊髓束）和控制认知域也被检查。结果：MCI患者穹窿组织体积分数降低。轴向和径向扩散率在钩状和PHC中增加，表明微观结构发生了更微妙的变化。在对照组中，穹窿组织体积分数是自由回忆的主要相关因素。相反，在MCI中，与左PHC的关系最强。在MCI中，钩肢和PHC的微观结构也与识别记忆和识别置信度相关。结论：MCI的情景记忆与多时间关联通路的结构有关。这些关联并不局限于穹窿，就像健康的年轻人和老年人一样。在轻度认知损伤中，由于穹窿受损，替代通路可能不成比例地影响情景记忆的表现。神经病学(R) 2012；79:2233 - 2240
Objective: To examine the pattern of association between microstructure of temporal lobe connections and the breakdown of episodic memory that is a core feature of mild cognitive impairment (MCI).Methods: Twenty-five individuals with MCI and 20 matched controls underwent diffusion MRI and cognitive assessment. Three temporal pathways were reconstructed by tractography: fornix, parahip-pocampal cingulum (PHC), and uncinate fasciculus. Tissue volume fraction-a tract-specific measure of atrophy-and microstructural measures were derived for each tract. To test specificity of associations, a comparison tract (corticospinal tract) and control cognitive domains were also examined.Results: In MCI, tissue volume fraction was reduced in the fornix. Axial and radial diffusivity were increased in uncinate and PHC implying more subtle microstructural change. In controls, tissue volume fraction in the fornix was the predominant correlate of free recall. In contrast, in MCI, the strongest relationship was with left PHC. Microstructure of uncinate and PHC also correlated with recognition memory, and recognition confidence, in MCI.Conclusions: Episodic memory in MCI is related to the structure of multiple temporal association pathways. These associations are not confined to the fornix, as they are in healthy young and older adults. In MCI, because of a compromised fornix, alternative pathways may contribute disproportionally to episodic memory performance. Neurology (R) 2012;79:2233-2240