BRAIN ACTIVATION PROFILES IN DYSLEXIA--A MEG STUDY

我们用全头脑磁图（MEG）方法（也称为磁源成像或MSI）获得的功能成像数据表明，在需要语音解码的任务中，个体失读症儿童的大脑激活的时空特征与个体非失读症儿童的大脑激活的时空特征存在显著差异。主要的差异集中在后颞上回和边缘上回、额下回以及最明显的角回的激活程度上。因此，我们在这个项目中的第一个目标将是评估这些初步发现的可靠性，有足够的80名非阅读障碍儿童和160名阅读障碍儿童的样本。第二个目的是评估，除了语音处理的差异，正字法和视觉形式处理的差异，在正常儿童和阅读困难儿童之间，是否有助于后者的异常激活。第三个目标是评估这样一个假设，即观察到的左颞顶区（包括角回）活动的减少，可能归因于该区域更普遍的功能障碍，这可能是许多与阅读障碍相关的认知缺陷的基础。除了上述目标之外，我们还将使用额外的统计分析来研究注意力缺陷对激活概况的可能贡献及其差异。最后，利用MEG激活谱是(a)为个体受试者计算的，(b)具有优异的时间分辨率的事实，我们将探索通过使用模糊聚类技术来揭示正常和阅读困难儿童谱中细微差异的可能性。详细描述个体特征的时空特征可能有助于未来研究评估干预策略对个体失读症儿童大脑功能重组的影响。

Functional imaging data we have obtained with the method of whole-head Magnetoencephalography (MEG), also referred to as Magnetic Source Imaging or MSI, indicate that the spatiotemporal profiles of brain activation of individual dyslexic children differ dramatically from those of individual non-dyslexic children during the performance of tasks that entail phonological decoding. The main differences in the profiles center on the degree of activation of the posterior superior temporal and supramarginal gyri, the inferior frontal area, and, most notably, the angular gyrus. Accordingly, our first aim in this project will be to assess the reliability of these preliminary findings with adequate samples of 80 non-dyslexic and 160 dyslexic children. The second aim will be to assess whether, in addition to differences in phonological processing, differences in orthographic and visual form processing, between normal and dyslexic children, contribute to the aberrant activation profile of the latter. The third aim will be to evaluate the hypothesis that the observed reduction of activity of the left temporoparietal area including the angular gyrus, may be attributed to a more general dysfunction of that region that may underlie many of the cognitive deficits associated with dyslexia. In addition to the above aims, we will investigate that possible contribution of attention deficits to the activation profiles and their differences using additional statistical analyses. Finally, taking advantage of the fact that MEG activation profiles are (a) computed for individual subjects, and (b) are characterized by excellent temporal resolution, we will explore the possibility of uncovering subtle differences in the profiles of normal and dyslexic children through the use of fuzzy clustering techniques. Detailed characterization of the spatiotemporal features of individual profiles may become useful in future studies for assessing the effects of intervention strategies on the functional cerebral reorganization of individual dyslexic children.