An fMRI study of verbal episodic memory encoding in amnestic mild cognitive impairment
An fMRI study of verbal episodic memory encoding in amnestic mild cognitive impairment
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DOI：
10.1016/j.cortex.2007.04.005
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发表时间：
2008-07-01
期刊：
影响因子：
3.6
通讯作者：
Walker, Zuzana
中科院分区：
文献类型：
--
作者：
Dannhauser, Thomas M.;Shergill, Sukhwinder S.;Walker, Zuzana
遗忘性轻度认知损害是阿尔茨海默病(AD)的一种高危且常为前驱症状的状态，以孤立的间歇性记忆障碍为特征。健康受试者的功能神经成像研究一致地报告了在言语情景记忆编码过程中左前额叶皮质(PFC)的激活。编码时PFC的激活与增强记忆的语义加工有关。本研究的目的是确定AMCI患者的言语情景记忆受损是否与PFC功能障碍有关。我们使用功能磁共振成像(FMRI)对10例aMCI患者和10例老年对照组进行了语言编码的比较。编码任务对语义加工的影响比较敏感。随后的再认被测试以衡量编码成功与否。行为学结果显示，在aMCI中，对语义相关干扰物(诱饵)的识别受损，错误识别率较低，这表明编码时的语义加工受损。两组都激活了左半球PFC、脑岛、运动前皮质和小脑，但两组比较发现，aMCI组左侧腹外侧区PFC激活减少。在对照组中，左侧腹外侧区PFC的激活程度与识别准确率呈正相关，而在aMCI组中则不相关。我们认为非MCI患者的言语情景记忆障碍与PFC功能障碍有关，PFC功能障碍影响编码时的语义加工。(C)2008年爱思唯尔·马森先生版权所有。
Amnestic mild cognitive impairment (aMCI) is a high-risk and often prodromal state for the development of Alzheimer's disease (AD) and is characterised by isolated episodic memory impairment. Functional neuroimaging studies in healthy subjects consistently report left prefrontal cortex (PFC) activation during verbal episodic memory encoding. The PFC activation at encoding is related to semantic processing which enhances memory. The purpose of this study was to ascertain whether impaired verbal episodic memory in aMCI is related to PFC dysfunction. Using functional magnetic resonance imaging (fMRI) we compared 10 aMCI patients with 10 elderly controls during verbal encoding. The encoding task was sensitive to the effects of semantic processing. Subsequent recognition was tested to measure encoding success. Behavioural results revealed impaired recognition and a lower false recognition rate for semantically related distracters (lures) in aMCI, which suggest impaired semantic processing at encoding. Both groups activated left hemispheric PFC, insula, pre-motor cortex and cerebellum, but group comparisons revealed decreased activation in left ventrolateral PFC in the aMCI group. The magnitude of activation in left ventrolateral PFC during encoding was positively correlated with recognition accuracy in the control group but not in the aMCI group. We propose that verbal episodic memory impairment in aMCI is related to PFC dysfunction which affects semantic processing at encoding. (C) 2008 Elsevier Masson Srl. All rights reserved.