Cyclotron Research Centre, University of Liège, Belgium.
Cortex. 2013 Jun;49(6):1566-84. doi: 10.1016/j.cortex.2012.11.017. Epub 2012 Dec 19.
Typical Alzheimer's disease (AD) is characterized by an impaired form of associative memory, recollection, that includes the controlled retrieval of associations. In contrast, familiarity-based memory for individual items may sometimes be preserved in the early stages of the disease. This is the first study that directly examines whole-brain regional activity during one core aspect of the recollection function: associative controlled episodic retrieval (CER), contrasted to item familiarity in AD patients. Cerebral activity related to associative CER and item familiarity in AD patients and healthy controls (HCs) was measured with functional magnetic resonance imaging during a word-pair recognition task to which the process dissociation procedure was applied. Some patients had null CER estimates (AD-), whereas others did show some CER abilities (AD+), although significantly less than HC. In contrast, familiarity estimates were equivalent in the three groups. In AD+, as in controls, associative CER activated the inferior precuneus/posterior cingulate cortex (PCC). When performing group comparisons, no region was found to be significantly more activated during CER in HC than AD+ and vice versa. However, during associative CER, functional connectivity between this region and the hippocampus, the inferior parietal and dorsolateral prefrontal cortex (DLPFC) was significantly higher in HC than in AD+. In all three groups, item familiarity was related to activation along the intraparietal sulcus (IPS). In conclusion, whereas the preserved automatic detection of an old item (without retrieval of accurate word association) is related to parietal activation centred on the IPS, the inferior precuneus/PCC supports associative CER ability in AD patients, as in HC. However, AD patients have deficient functional connectivity during associative CER, suggesting that the residual recollection function in these patients might be impoverished by the lack of some recollection-related aspects such as autonoetic quality, episodic details and verification.
典型的阿尔茨海默病（AD）的特征是联想记忆受损，包括对联想的控制检索。相比之下，在疾病的早期，对单个项目的熟悉记忆有时可能会保留下来。这是第一项直接研究回忆功能核心方面的全脑区域活动的研究：与 AD 患者的项目熟悉度相比，联想控制的情节检索（CER）。在单词对识别任务中，使用功能磁共振成像测量了与联想 CER 和项目熟悉度相关的大脑活动，该任务应用了过程分离程序。一些患者的 CER 估计值为零（AD-），而另一些患者则表现出一些 CER 能力（AD+），尽管明显低于 HC。相比之下，三组的熟悉度估计值相当。在 AD+中，与对照组一样，联想 CER 激活了下顶叶/后扣带回皮层（PCC）。在进行组间比较时，没有发现该区域在 HC 中比 AD+更显著地激活，反之亦然。然而，在联想 CER 期间，与海马体、下顶叶和背外侧前额叶皮层（DLPFC）的功能连接在 HC 中显著高于 AD+。在所有三组中，项目熟悉度与沿顶内沟（IPS）的激活有关。总之，虽然自动检测旧项目（不检索准确的单词联想）的能力与以 IPS 为中心的顶叶激活有关，但下顶叶后扣带回皮层支持 AD 患者的联想 CER 能力，就像在 HC 中一样。然而，AD 患者在联想 CER 期间的功能连接不足，这表明这些患者的残留回忆功能可能因缺乏某些与回忆相关的方面而变得匮乏，如自主体验、情节细节和验证。
