Center for Alzheimer Research and Treatment, Brigham and Women's Hospital, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
J Alzheimers Dis. 2012;31 Suppl 3(0 3):S155-67. doi: 10.3233/JAD-2012-120730.
Functional magnetic resonance imaging (fMRI) is a non-invasive technique that has come into common use to examine neural network function in normal and impaired cognitive states. Using this promising type of analysis, researchers have identified the presence of anatomically distributed regions operating as large-scale neural networks, which are observed both during the performance of associative memory tasks and in the resting state. The assembly of these anatomically distinct regions into functional ensembles and their choreographed activation and deactivation sets the stage for complex behaviors such as the formation and retrieval of associative memories. We review progress in the use of task-related and task-free MRI to elucidate the changes in neural activity in normal older individuals, patients with mild cognitive impairment, and those with Alzheimer's disease, focusing on the altered activity of the default mode network and medial temporal lobe. We place task-free fMRI studies into the larger context of more traditional, task-based fMRI studies of human memory, which have firmly established the critical role of the medial temporal lobe in associative encoding. Lastly, we discuss the data from our group and others that suggests task-free MRI and task-based fMRI may prove useful as non-invasive biomarkers in studying the progression of memory failure over the course of Alzheimer's disease.
功能磁共振成像（fMRI）是一种非侵入性技术，已广泛用于研究正常和受损认知状态下的神经网络功能。利用这种有前途的分析类型，研究人员已经确定了存在作为大规模神经网络运作的解剖上分布的区域，这些区域在执行联想记忆任务和休息状态时都可以观察到。这些解剖上不同的区域组装成功能集合，以及它们的协调激活和去激活为复杂行为（如联想记忆的形成和检索）奠定了基础。我们回顾了使用任务相关和无任务磁共振成像来阐明正常老年人、轻度认知障碍患者和阿尔茨海默病患者的神经活动变化的进展，重点关注默认模式网络和内侧颞叶的改变活动。我们将无任务 fMRI 研究置于更传统的基于任务的人类记忆 fMRI 研究的更大背景下，这些研究已经确定了内侧颞叶在联想编码中的关键作用。最后，我们讨论了我们小组和其他人的数据，这些数据表明无任务 fMRI 和基于任务的 fMRI 可能被证明是研究阿尔茨海默病过程中记忆失败进展的有用的非侵入性生物标志物。
