Mutlu Justine, Landeau Brigitte, Tomadesso Clémence, de Flores Robin, Mézenge Florence, de La Sayette Vincent, Eustache Francis, Chételat Gaël
Institut National de la Santé et de la Recherche Médicale, U1077Caen, France; Université de Caen Normandie UMR-S1077Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077Caen, France; CHU de Caen, U1077Caen, France.
Institut National de la Santé et de la Recherche Médicale, U1077Caen, France; Université de Caen Normandie UMR-S1077Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077Caen, France; CHU de Caen, Service de NeurologieCaen, France.
Front Neurosci. 2016 Dec 21;10:582. doi: 10.3389/fnins.2016.00582. eCollection 2016.
The posterior cingulate cortex (PCC) is a critical brain network hub particularly sensitive to Alzheimer's disease (AD) and can be subdivided into ventral (vPCC) and dorsal (dPCC) regions. The aim of the present study was to highlight functional connectivity (FC) disruption, atrophy, and hypometabolism within the ventral and dorsal PCC networks in patients with amnestic mild cognitive impairment (aMCI) or AD. Forty-three healthy elders (HE) (68.7 ± 6 years), 34 aMCI (73.4 ± 6.8 years) and 24 AD (70.9 ± 9.1 years) patients underwent resting-state functional MRI, anatomical T1-weighted MRI and FDG-PET scans. We compared FC maps obtained from the vPCC and dPCC seeds in HE to identify the ventral and dorsal PCC networks. We then compared patients and HE on FC, gray matter volume and metabolism within each network. In HE, the ventral PCC network involved the hippocampus and posterior occipitotemporal and temporoparietal regions, whereas the dorsal PCC network included mainly frontal, middle temporal and temporoparietal areas. aMCI patients had impaired ventral network FC in the bilateral hippocampus, but dorsal network FC was preserved. In AD, the ventral network FC disruption had spread to the left parahippocampal and angular regions, while the dorsal network FC was also affected in the right middle temporal cortex. The ventral network was atrophied in the bilateral hippocampus in aMCI patients, and in the vPCC and angular regions as well in AD patients. The dorsal network was only atrophied in AD patients, in the dPCC, bilateral supramarginal and temporal regions. By contrast, hypometabolism was already present in both the vPCC and dPCC networks in aMCI patients, and further extended to include the whole networks in AD patients. The vPCC and dPCC connectivity networks were differentially sensitive to AD. Atrophy and FC disruption were only present in the vPCC network in aMCI patients, and extended to the dPCC network in AD patients, suggesting that the pathology spreads from the vPCC to the dPCC networks. By contrast, hypometabolism seemed to follow a different route, as it was present in both networks since the aMCI stage, possibly reflecting not only local disruption but also distant synaptic dysfunction.
后扣带回皮质（PCC）是一个关键的脑网络枢纽，对阿尔茨海默病（AD）尤为敏感，可细分为腹侧（vPCC）和背侧（dPCC）区域。本研究的目的是突出遗忘型轻度认知障碍（aMCI）或AD患者腹侧和背侧PCC网络内的功能连接（FC）中断、萎缩和代谢减低情况。43名健康老年人（HE）（68.7±6岁）、34名aMCI患者（73.4±6.8岁）和24名AD患者（70.9±9.1岁）接受了静息态功能磁共振成像、解剖学T1加权磁共振成像和氟代脱氧葡萄糖正电子发射断层显像（FDG-PET）扫描。我们将从HE的vPCC和dPCC种子点获得的FC图谱进行比较，以识别腹侧和背侧PCC网络。然后，我们比较了患者和HE在每个网络内的FC、灰质体积和代谢情况。在HE中，腹侧PCC网络涉及海马体以及枕颞后部和颞顶叶区域，而背侧PCC网络主要包括额叶、颞中回和颞顶叶区域。aMCI患者双侧海马体的腹侧网络FC受损，但背侧网络FC得以保留。在AD患者中，腹侧网络FC中断已蔓延至左侧海马旁回和角回区域，而背侧网络FC在右侧颞中皮质也受到影响。aMCI患者双侧海马体的腹侧网络萎缩，AD患者的vPCC和角回区域也出现萎缩。背侧网络仅在AD患者中出现萎缩，位于dPCC、双侧缘上回和颞叶区域。相比之下，aMCI患者的vPCC和dPCC网络均已出现代谢减低，且在AD患者中进一步扩展至整个网络。vPCC和dPCC连接网络对AD的敏感性不同。萎缩和FC中断仅在aMCI患者的vPCC网络中出现，在AD患者中扩展至dPCC网络，这表明病变从vPCC网络蔓延至dPCC网络。相比之下，代谢减低似乎遵循不同的路径，因为自aMCI阶段起两个网络均出现代谢减低，这可能不仅反映了局部破坏，还反映了远距离的突触功能障碍。
