Shames H, Raz N, Levin Netta
fMRI unit, Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah Hebrew-University Medical Center, Hadassah Ein Karem, P.O.B 12000, 91120, Jerusalem, Israel.
J Neurol. 2015 Jul;262(7):1751-61. doi: 10.1007/s00415-015-7774-8. Epub 2015 May 16.
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome in which the most pronounced pathologic involvement is in the occipito-parietal visual regions. Herein, we aimed to better define the cortical reflection of this unique syndrome using a thorough battery of behavioral and functional MRI (fMRI) tests. Eight PCA patients underwent extensive testing to map their visual deficits. Assessments included visual functions associated with lower and higher components of the cortical hierarchy, as well as dorsal- and ventral-related cortical functions. fMRI was performed on five patients to examine the neuronal substrate of their visual functions. The PCA patient cohort exhibited stereopsis, saccadic eye movements and higher dorsal stream-related functional impairments, including simultant perception, image orientation, figure-from-ground segregation, closure and spatial orientation. In accordance with the behavioral findings, fMRI revealed intact activation in the ventral visual regions of face and object perception while more dorsal aspects of perception, including motion and gestalt perception, revealed impaired patterns of activity. In most of the patients, there was a lack of activity in the word form area, which is known to be linked to reading disorders. Finally, there was evidence of reduced cortical representation of the peripheral visual field, corresponding to the behaviorally assessed peripheral visual deficit. The findings are discussed in the context of networks extending from parietal regions, which mediate navigationally related processing, visually guided actions, eye movement control and working memory, suggesting that damage to these networks might explain the wide range of deficits in PCA patients.
后部皮质萎缩（PCA）是一种神经退行性综合征，其中最显著的病理累及部位是枕顶视觉区域。在此，我们旨在通过一系列全面的行为和功能磁共振成像（fMRI）测试，更好地界定这种独特综合征的皮质反映。八名PCA患者接受了广泛测试以绘制其视觉缺陷图谱。评估包括与皮质层级较低和较高成分相关的视觉功能，以及与背侧和腹侧相关的皮质功能。对五名患者进行了fMRI检查，以研究其视觉功能的神经元基质。PCA患者队列表现出立体视觉、眼球扫视运动以及与背侧流相关的高级功能障碍，包括同时感知、图像定向、图形-背景分离、闭合和空间定向。与行为学发现一致，fMRI显示面部和物体感知的腹侧视觉区域激活完整，而包括运动和格式塔感知在内的更多背侧感知方面则显示出受损的活动模式。在大多数患者中，词形区缺乏活动，已知该区域与阅读障碍有关。最后，有证据表明外周视野的皮质代表减少，这与行为学评估的外周视觉缺陷相对应。研究结果在从顶叶区域延伸的网络背景下进行了讨论，这些网络介导与导航相关的处理、视觉引导的动作、眼球运动控制和工作记忆，这表明这些网络的损伤可能解释了PCA患者广泛的缺陷。
