INSERM U 1127, CNRS UMR 7225, Sorbonne Universités, and Université Pierre et Marie Curie-Paris 6, UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013 Paris, France.
Department of Neurology, Institut de la mémoire et de la maladie d'Alzheimer, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France.
J Alzheimers Dis. 2016;51(4):1119-30. doi: 10.3233/JAD-150934.
Posterior cortical atrophy (PCA) induces progressive dysfunction of ventral and dorsal visual networks. Little is known, however, about corresponding changes in functional connectivity (FC).
To investigate FC changes in the visual networks, their relationship with cortical atrophy, and the association with Alzheimer's disease (AD) pathology.
Ten PCA patients and 28 age-matched controls participated in the study. Using resting state fMRI, we measured FC in ventral and dorsal cortical visual networks, defined on the basis of a priori knowledge of long-range white matter connections. To assess the relationships with AD, we determined AD biomarkers in cerebrospinal fluid and FC in the default mode network (DMN), which is vulnerable to AD pathology. Voxel-based morphometry analysis assessed the pattern of grey matter (GM) atrophy.
PCA patients showed GM atrophy in bilateral occipital and inferior parietal regions. PCA patients had lower FC levels in a ventral network than controls, but higher FC in inferior components of the dorsal network. In particular, the increased connectivity correlated with greater GM atrophy in occipital regions. All PCA patients had positive cerebrospinal fluid biomarkers for AD; however, FC in global DMN did not differ from controls.
FC in PCA reflects brain structure in a non-univocal way. Hyperconnectivity of dorsal networks may indicate aberrant communication in response to posterior brain atrophy or processes of neural resilience during the initial stage of brain dysfunction. The lack of difference from controls in global DMN FC highlights the atypical nature of PCA with respect to typical AD.
后部皮质萎缩（PCA）导致腹侧和背侧视觉网络的进行性功能障碍。然而，关于相应的功能连接（FC）变化知之甚少。
研究视觉网络的 FC 变化，它们与皮质萎缩的关系，以及与阿尔茨海默病（AD）病理的关联。
10 名 PCA 患者和 28 名年龄匹配的对照者参与了研究。使用静息状态 fMRI，我们测量了基于长程白质连接的先验知识定义的腹侧和背侧皮质视觉网络的 FC。为了评估与 AD 的关系，我们确定了脑脊液中的 AD 生物标志物和默认模式网络（DMN）中的 FC，DMN 易受 AD 病理影响。体素形态计量学分析评估了灰质（GM）萎缩的模式。
PCA 患者表现为双侧枕叶和下顶叶区域的 GM 萎缩。与对照组相比，PCA 患者的腹侧网络 FC 水平较低，但背侧网络的下侧 FC 较高。特别是，增加的连通性与枕叶区域更大的 GM 萎缩相关。所有 PCA 患者的脑脊液 AD 生物标志物均为阳性；然而，全局 DMN 的 FC 与对照组无差异。
PCA 中的 FC 以一种非单一的方式反映大脑结构。背侧网络的过度连通可能表明在后脑萎缩或在脑功能障碍的初始阶段神经恢复过程中出现异常的通讯。与对照组相比，全局 DMN FC 无差异突出了 PCA 相对于典型 AD 的非典型性质。
