Functional and morphometric brain dissociation between dyslexia and reading ability
Functional and morphometric brain dissociation between dyslexia and reading ability
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DOI：
10.1073/pnas.0609399104
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发表时间：
2007-03-06
影响因子：
11.1
通讯作者：
Gabrieli, John D. E.
中科院分区：
文献类型：
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作者：
Hoeft, Fumiko;Meyler, Ann;Gabrieli, John D. E.
在功能性神经影像学研究中，患有阅读障碍的个体经常表现为左顶叶皮层的低激活和左额叶下皮层的高激活，但没有证据表明如何解释低激活和高激活与阅读障碍的不同关系。为了解决这个问题，我们通过功能性MRI测量了视觉词韵判断与视觉交叉注视休息时的大脑激活情况，并通过基于体素的形态测量法测量了阅读困难青少年的灰质形态，并与(i)年龄匹配组和（ii）阅读匹配组进行了比较，这些组比阅读困难组年轻，但在阅读表现上与阅读困难组相当。相对于年龄匹配组（n = 19，平均14.4岁），阅读困难组（n = 19，平均14.4岁）表现为左侧顶叶和双侧梭状皮质活性降低，左侧额下回和额中回、尾状体和丘脑活性升高。相对于阅读匹配组（n = 12，平均9.8岁），阅读困难组（n = 12，平均14.5岁）在左顶叶和梭状回区域也表现出低激活，但在相对于年龄匹配的对照组表现出高激活的所有四个区域都表现出相同的激活。在失读症组表现出非典型激活的区域，相对于两个对照组，只有左顶叶区域表现出灰质体积减少。因此，阅读障碍中过度激活的区域反映了与当前阅读能力水平相关的过程，独立于阅读障碍。相反，失读症的低激活区域反映了与失读症本身相关的功能非典型性，独立于当前的阅读能力，并且与失读症的非典型性脑形态有关。
In functional neuroimaging studies, individuals with dyslexia frequently exhibit both hypoactivation, often in the left parietotemporal cortex, and hyperactivation, often in the left inferior frontal cortex, but there has been no evidence to suggest how to interpret the differential relations of hypoactivation and hyperactivation to dyslexia. To address this question, we measured brain activation by functional MRI during visual word rhyme judgment compared with visual cross-hair fixation rest, and we measured gray matter morphology by voxel-based morphometry in dyslexic adolescents in comparison with (i) an age-matched group, and (ii) a reading-matched group younger than the dyslexic group but equal to the dyslexic group in reading performance. Relative to the age-matched group (n = 19; mean 14.4 years), the dyslexic group (n = 19; mean 14.4 years) exhibited hypoactivation in left parietal and bilateral fusiform cortices and hyperactivation in left inferior and middle frontal gyri, caudate, and thalamus. Relative to the reading-matched group (n = 12; mean 9.8 years), the dyslexic group (n = 12; mean 14.5 years) also exhibited hypoactivation in left parietal and fusiform regions but equal activation in all four areas that had exhibited hyperactivation relative to age-matched controls as well. In regions that exhibited atypical activation in the dyslexic group, only the left parietal region exhibited reduced gray matter volume relative to both control groups. Thus, areas of hyperactivation in dyslexia reflected processes related to the level of current reading ability independent of dyslexia. In contrast, areas of hypoactivation in dyslexia reflected functional atypicalities related to dyslexia itself, independent of current reading ability, and related to atypical brain morphology in dyslexia.