Laboratoire Epilepsies et Cognition, INSERM U751, Marseille, France; Centre de Résonance Magnétique Biologique et Médicale (CRMBM), UMR CNRS 6612, Marseille, France.
Neuroimage. 2011 Sep 15;58(2):687-97. doi: 10.1016/j.neuroimage.2011.05.090. Epub 2011 Jun 21.
Spontaneous fluctuations in the blood oxygenation level-dependent (BOLD) signal, as measured by functional magnetic resonance imaging (fMRI) at rest, exhibit a temporally coherent activity thought to reflect functionally relevant networks. Antero-mesial temporal structures are the site of early pathological changes in Alzheimer's disease and have been shown to be critical for declarative memory. Our study aimed at exploring the functional impact of basal connectivity of an anterior temporal network (ATN) on declarative memory. A heterogeneous group of subjects with varying performance on tasks assessing memory was therefore selected, including healthy subjects and patients with isolated memory complaint, amnestic Mild Cognitive Impairment (aMCI) and mild Alzheimer's disease (AD). Using Independent Component Analysis on resting-state fMRI, we extracted a relevant anterior temporal network (ATN) composed of the perirhinal and entorhinal cortex, the hippocampal head, the amygdala and the lateral temporal cortex extending to the temporal pole. A default mode network and an executive-control network were also selected to serve as control networks. We first compared basal functional connectivity of the ATN between patients and control subjects. Relative to controls, patients exhibited significantly increased functional connectivity in the ATN during rest. Specifically, voxel-based analysis revealed an increase within the inferior and superior temporal gyrus and the uncus. In the patient group, positive correlations between averaged connectivity values of ATN and performance on anterograde and retrograde object-based memory tasks were observed, while no correlation was found with other evaluated cognitive measures. These correlations were specific to the ATN, as no correlation between performance on memory tasks and the other selected networks was found. Taken together, these findings provide evidence that basal connectivity inside the ATN network has a functional role in object-related, context-free memory. They also suggest that increased connectivity at rest within the ATN could reflect compensatory mechanisms that occur in response to early pathological insult.
静息状态下血氧水平依赖（BOLD）信号的自发波动，通过功能磁共振成像（fMRI）测量，表现出时间上连贯的活动，被认为反映了功能相关的网络。前内侧颞叶结构是阿尔茨海默病早期病理变化的部位，并且已经被证明对陈述性记忆至关重要。我们的研究旨在探索前颞叶网络（ATN）的基础连接对陈述性记忆的功能影响。因此，选择了一组具有不同记忆任务表现的受试者，包括健康受试者和有孤立性记忆主诉、遗忘型轻度认知障碍（aMCI）和轻度阿尔茨海默病（AD）的患者。我们使用静息态 fMRI 的独立成分分析，提取了一个由边缘下和内嗅皮层、海马头部、杏仁核和向颞极延伸的外侧颞叶组成的相关前颞叶网络（ATN）。还选择了默认模式网络和执行控制网络作为对照网络。我们首先比较了患者和对照组之间 ATN 的基础功能连接。与对照组相比，患者在休息时表现出 ATN 功能连接显著增加。具体而言，基于体素的分析显示颞叶下回和上回以及钩回的增加。在患者组中，观察到 ATN 的平均连接值与顺行和逆行基于物体的记忆任务的表现之间存在正相关，而与其他评估的认知测量值之间没有相关性。这些相关性是 ATN 特有的，因为在记忆任务的表现与其他选择的网络之间没有相关性。总之，这些发现提供了证据表明 ATN 网络内的基础连接在物体相关、无上下文记忆中具有功能作用。它们还表明，ATN 内静息状态下连接的增加可能反映了对早期病理损伤的代偿机制。
