Maisog José M, Einbinder Erin R, Flowers D Lynn, Turkeltaub Peter E, Eden Guinevere F
Center for the Study of Learning, Georgetown University Medical Center, Washington, DC 20057, USA.
Ann N Y Acad Sci. 2008 Dec;1145:237-59. doi: 10.1196/annals.1416.024.
Reading and phonological processing deficits have been the primary focus of neuroimaging studies addressing the neurologic basis of developmental dyslexia, but to date there has been no objective assessment of the consistency of these findings. To address this issue, spatial coordinates reported in the literature were submitted to two parallel activation likelihood estimate (ALE) meta-analyses. First, a meta-analysis including 96 foci from nine publications identified regions where typical readers are likely to show greater activation than dyslexics: two left extrastriate areas within BA 37, precuneus, inferior parietal cortex, superior temporal gyrus, thalamus, and left inferior frontal gyrus. Right hemisphere ALE foci representing hypoactivity in dyslexia were found in the fusiform, postcentral, and superior temporal gyri. To identify regions in which dyslexic subjects reliably show greater activation than controls, 75 foci from six papers were entered into a second meta-analysis. Here ALE results revealed hyperactivity associated with dyslexia in right thalamus and anterior insula. These findings suggest that during the performance of a variety of reading tasks, normal readers activate left-sided brain areas more than dyslexic readers do, whereas dyslexia is associated with greater right-sided brain activity. The most robust result was in left extrastriate cortex, where hypoactivity associated with dyslexia was found. However, the ALE maps provided no support for cerebellar dysfunction, nor for hyperactivity in left frontal cortex in dyslexia, suggesting that these findings, unlike those described above, are likely to be more varied in terms of their reproducibility or spatial location.
阅读和语音处理缺陷一直是神经影像学研究关注发育性阅读障碍神经学基础的主要焦点，但迄今为止，尚未对这些研究结果的一致性进行客观评估。为解决这一问题，将文献中报道的空间坐标提交给两项平行的激活可能性估计（ALE）元分析。首先，一项包含来自9篇出版物的96个病灶的元分析确定了典型读者可能比阅读障碍者表现出更强激活的区域：BA 37内的两个左侧纹外区、楔前叶、顶下小叶、颞上回、丘脑和左侧额下回。在梭状回、中央后回和颞上回发现了代表阅读障碍者活动减退的右侧半球ALE病灶。为了确定阅读障碍受试者比对照组可靠地表现出更强激活的区域，将来自6篇论文的75个病灶纳入第二项元分析。在此，ALE结果显示右侧丘脑和前岛叶与阅读障碍相关的活动亢进。这些发现表明，在执行各种阅读任务时，正常读者比阅读障碍读者更多地激活左侧脑区，而阅读障碍与右侧脑区更强的活动相关。最显著的结果出现在左侧纹外皮层，在那里发现了与阅读障碍相关的活动减退。然而，ALE图谱并未支持小脑功能障碍，也未支持阅读障碍者左侧额叶皮层的活动亢进，这表明与上述发现不同，这些发现的可重复性或空间位置可能更具多样性。
