Purcell Jeremy, Sebastian Rajani, Leigh Richard, Jarso Samson, Davis Cameron, Posner Joseph, Wright Amy, Hillis Argye E
Cognitive Science, Johns Hopkins University, Baltimore, MD, 21218, USA.
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
Cortex. 2017 Jul;92:103-118. doi: 10.1016/j.cortex.2017.03.022. Epub 2017 Apr 8.
An intact orthographic processing system is critical for normal reading and spelling. Here we investigate the neural changes associated with impairment and subsequent recovery of the orthographic lexical processing system in an individual with an ischemic left posterior cerebral artery (PCA) stroke. This work describes a longitudinal case study of a patient, whose initials are MMY, with impairments in orthographic lexical processing for reading and spelling at stroke onset, and who recovered these skills within 1 year post stroke. We tested the hypothesis that this acute impairment to reading and spelling would be associated with a selective loss of neural activation in the left fusiform gyrus (FG), and that subsequent recovery would be associated with a gain of neural activation in this region. MMY's case provided a unique opportunity to assess the selectivity of neural changes because she demonstrated a behavioral recovery of naming as well; i.e., if there is neural recovery for reading and spelling, but not naming, then these neural changes are selective to the recovery of orthographic processing. To test our hypothesis, we examined longitudinal behavioral and functional magnetic resonance imaging (fMRI) data of reading, spelling, and visual object naming acquired acutely, 3 weeks, 5 months, and one year post stroke. In confirmation of our hypothesis, the loss and subsequent gain of orthographic lexical processing was associated with up-regulation of neural activation in areas previously associated with orthographic lexical processing: i.e., the left mid-FG and inferior frontal junction (IFJ). Furthermore, these neural changes were found to be selective to orthographic processing, as they were observed for reading and spelling, but not for visual object naming within the left mid-FG. This work shows that left PCA stroke can temporarily and selectively disrupt the orthographic lexical processing system, not only in the posterior region adjacent to the stroke, but also in relatively distant frontal orthographic processing regions.
完整的正字法处理系统对于正常的阅读和拼写至关重要。在此，我们研究了一名左大脑后动脉（PCA）缺血性中风患者的正字法词汇处理系统受损及随后恢复过程中相关的神经变化。这项工作描述了对一名患者（姓名首字母为MMY）的纵向病例研究，该患者在中风发作时阅读和拼写的正字法词汇处理存在障碍，并在中风后1年内恢复了这些技能。我们检验了这样一个假设，即阅读和拼写的这种急性损伤会与左侧梭状回（FG）神经激活的选择性丧失相关，而随后的恢复会与该区域神经激活的增加相关。MMY的病例提供了一个评估神经变化选择性的独特机会，因为她在命名方面也表现出行为恢复；也就是说，如果存在阅读和拼写的神经恢复，但命名没有恢复，那么这些神经变化对正字法处理的恢复是有选择性的。为了检验我们的假设，我们检查了中风后即刻、3周、5个月和1年获取的阅读、拼写和视觉物体命名的纵向行为和功能磁共振成像（fMRI）数据。证实我们的假设，正字法词汇处理的丧失及随后的恢复与先前与正字法词汇处理相关区域的神经激活上调有关：即左侧FG中部和额下交界区（IFJ）。此外，发现这些神经变化对正字法处理具有选择性，因为在左侧FG中部观察到了阅读和拼写的神经变化，但视觉物体命名没有。这项工作表明，左侧PCA中风可暂时且选择性地破坏正字法词汇处理系统，不仅在中风邻近的后部区域，而且在相对较远的额叶正字法处理区域。
