Department of Radiology, Michigan State University, East Lansing, MI, USA.
Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA.
J Alzheimers Dis. 2020;77(3):1025-1042. doi: 10.3233/JAD-200173.
Postmortem studies of Alzheimer's disease (AD) brains not only find amyloid-β (Aβ) and neurofibrillary tangles (NFT) in the primary and associative visual cortical areas, but also reveal a temporally successive sequence of AD pathology beginning in higher-order visual association areas, followed by involvement of lower-order visual processing regions with disease progression, and extending to primary visual cortex in late-stage disease. These findings suggest that neuronal loss associated with Aβ and NFT aggregation in these areas may alter not only the local neuronal activation but also visual neural network activity.
Applying a novel method to identify the visual functional network and investigate the association of the network changes with disease progression.
To investigate the effect of AD on the face-evoked visual-processing network, 8 severe AD (SAD) patients, 11 mild/moderate AD (MAD), and 26 healthy senior (HS) controls undertook a task-fMRI study of viewing face photos.
For the HS, the identified group-mean visual-processing network in the ventral pathway started from V1 and ended within the fusiform gyrus. In contrast, this network was disrupted and reduced in the AD patients in a disease-severity dependent manner: for the MAD patients, the network was disrupted and reduced mainly in the higher-order visual association areas; for the SAD patients, the network was nearly absent in the higher-order association areas, and disrupted and reduced in the lower-order areas.
This finding is consistent with the current canonical view of the temporally successive sequence of AD pathology through visual cortical areas.
阿尔茨海默病（AD）患者尸检研究不仅在初级和联合视觉皮质区发现了淀粉样蛋白-β（Aβ）和神经原纤维缠结（NFT），还揭示了 AD 病理学的时间顺序，从高级视觉联合区开始，随着疾病进展逐渐累及低级视觉处理区，并在疾病晚期扩展到初级视觉皮质区。这些发现表明，这些区域中与 Aβ和 NFT 聚集相关的神经元丧失不仅可能改变局部神经元激活，还可能改变视觉神经网络活动。
应用一种新方法来识别视觉功能网络，并研究网络变化与疾病进展的关系。
为了研究 AD 对视觉处理网络的影响，8 名严重 AD（SAD）患者、11 名轻度/中度 AD（MAD）患者和 26 名健康老年人（HS）对照组接受了观看面部照片的任务 fMRI 研究。
对于 HS，鉴定的组平均视觉处理网络在腹侧通路中始于 V1，并终止于梭状回。相比之下，AD 患者的网络以疾病严重程度依赖的方式被破坏和减少：对于 MAD 患者，网络主要在高级视觉联合区被破坏和减少；对于 SAD 患者，网络在高级联合区几乎不存在，在低级区被破坏和减少。
这一发现与 AD 病理学在视觉皮质区的时间顺序的当前经典观点一致。
