Pure alexia as a disconnection syndrome: New diffusion imaging evidence for an old concept
Pure alexia as a disconnection syndrome: New diffusion imaging evidence for an old concept
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DOI：
10.1016/j.cortex.2008.05.003
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发表时间：
2008-09-01
期刊：
影响因子：
3.6
通讯作者：
Cohen, Laurent
中科院分区：
文献类型：
--
作者：
Epelbaum, Stephane;Pinel, Philippe;Cohen, Laurent
功能性神经影像学和对脑损伤患者的研究使我们有可能描绘出阅读的大脑系统的主要组成部分。然而，对着这个网络内的信息流的解剖连接仍然很难定义。在这里，我们研究了视觉词形区（VWFA）的连接性，视觉词形区是实现字母串不变识别的阅读网络的关键组成部分，并且可重复地位于左侧枕颞沟。扩散图像和功能成像数据收集在一个病人谁开发纯失读症后，在他的VWFA附近的小手术病变。我们有一个独特的机会来比较术前、术后早期和术后晚期获得的图像。扩散图像与白色物质纤维束成像和基于体素的形态学分析表明，VWFA主要通过下纵束（ILF）与枕叶皮质相连，并通过弓状束与外侧裂周语言区（缘上回）相连。手术后，我们观察到ILF的进行性和选择性变性，而VWFA解剖结构完整。这使我们能够确定该纤维束在正常阅读中的关键因果作用，并表明其中断是纯粹失读症的一种病理生理机制，从而澄清了关于断开在神经认知障碍中的作用的长期争论。(C)© 2008 Elsevier Masson Srl保留所有权利。
Functional neuroimaging and studies of brain-damaged patients made it possible to delineate the main components of the cerebral system for word reading. However, the anatomical connections subtending the flow of information within this network are still poorly defined. Here we study the connectivity of the Visual Word Form Area (VWFA), a pivotal component of the reading network achieving the invariant identification of letter strings, and reproducibly located in the left lateral occipitotemporal sulcus. Diffusion images and functional imaging data were gathered in a patient who developed pure alexia following a small surgical lesion in the vicinity of his VWFA. We had a unique opportunity to compare images obtained before, early after, and late after surgery. Analysis of diffusion images with white matter tractography and voxel-based morphometry showed that the VWFA was mainly linked to the occipital cortex through the inferior longitudinal fasciculus (ILF), and to perisylvian language areas (supramarginal gyrus) through the arcuate fasciculus. After surgery, we observed the progressive and selective degeneration of the ILF, while the VWFA was anatomically intact. This allowed us to establish the critical causal role of this fiber tract in normal reading, and to show that its disruption is one pathophysiological mechanism of pure alexia, thus clarifying a long-standing debate on the role of disconnection in neurocognitive disorders. (C) 2008 Elsevier Masson Srl All rights reserved.