Functional abnormalities of the medial temporal lobe memory system in mild cognitive impairment and Alzheimer's disease: Insights from functional MRI studies
Functional abnormalities of the medial temporal lobe memory system in mild cognitive impairment and Alzheimer's disease: Insights from functional MRI studies
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DOI：
10.1016/j.neuropsychologia.2007.11.030
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发表时间：
2008-01-01
期刊：
影响因子：
2.6
通讯作者：
Sperling, Reisa A.
中科院分区：
文献类型：
--
作者：
Dickerson, Bradford C.;Sperling, Reisa A.
功能磁共振成像(FMRI)对轻度认知损害(MCI)和阿尔茨海默病(AD)的研究已经开始揭示患有记忆障碍的人类记忆回路功能的异常。由于内侧颞叶(MTL)记忆系统是阿尔茨海默病(AD)非常早期的病理部位，这里综述的一些研究集中在大脑的这一区域。当个体被临床诊断为阿尔茨海默病时，实质性的记忆损害似乎不仅与MTL萎缩有关，而且与记忆任务执行过程中的激活不足有关。在痴呆之前，当个体开始表现出记忆障碍的迹象和症状时，海马结构和MTL记忆系统的其他组成部分在记忆任务执行过程中表现出实质性的功能异常。看来，在MCI的早期，当记忆障碍和海马萎缩不那么突出时，可能存在MTL回路的过度激活，可能代表着低效的代偿活动。在MCI过程的后期，当存在相当大的记忆缺陷时，MTL区域在尝试学习期间不再能够激活，就像AD痴呆的情况一样。最近MCI和AD的fMRI数据开始揭示MTL记忆系统的功能活动异常与大脑功能连接区域(如楔前叶)之间的关系。随着这项工作的不断成熟，它可能有助于我们理解人脑中的基本记忆过程，以及这些过程是如何在记忆障碍中受到干扰的。我们希望这些洞察力将转化为将与任务相关的脑功能测量纳入诊断评估或治疗监测，例如用于临床试验。(C)2007爱思唯尔有限公司。保留所有权利。
Functional MRI (fMRI) studies of mild cognitive impairment (MCI) and Alzheimer's disease (AD) have begun to reveal abnormalities in memory circuit function in humans suffering from memory disorders. Since the medial temporal lobe (MTL) memory system is a site of very early pathology in AD, a number of studies, reviewed here, have focused on this region of the brain. By the time individuals are diagnosed clinically with AD dementia, the substantial memory impairments appear to be associated with not only MTL atrophy but also hypoactivation during memory task performance. Prior to dementia, when individuals are beginning to manifest signs and symptoms of memory impairment, the hippocampal formation and other components of the MTL memory system exhibit substantial functional abnormalities during memory task performance. It appears that, early in the course of MCI when memory deficits and hippocampal atrophy are less prominent, there may be hyperactivation of MTL circuits, possibly representing inefficient compensatory activity. Later in the course of MCI, when considerable memory deficits are present, MTL regions are no longer able to activate during attempted learning, as is the case in AD dementia. Recent fMRI data in MCI and AD are beginning to reveal relationships between abnormalities of functional activity in the MTL memory system and in functionally connected brain regions, such as the precuneus. As this work continues to mature, it will likely contribute to our understanding of fundamental memory processes in the human brain and how these are perturbed in memory disorders. We hope these insights will translate into the incorporation of measures of task-related brain function into diagnostic assessment or therapeutic monitoring, such as for use in clinical trials. (c) 2007 Elsevier Ltd. All rights reserved.