BRAIN ACTIVATION PROFILES IN DYSLEXIA--A MEG STUDY

我们用全头磁脑图(MEG)方法获得的功能成像数据，也被称为磁源成像(MSI)，表明在需要进行语音解码的任务执行过程中，阅读障碍儿童个体的大脑激活的时空分布与非阅读障碍儿童个体的大脑激活的时空分布显著不同。侧貌的主要差异集中在后部颞叶上回和缘上回，额叶下部，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通过80名非阅读困难儿童和160名阅读困难儿童的足够样本来评估这些初步发现的可靠性。第二个目标是评估，除了语音加工的差异外，正常儿童和阅读障碍儿童在拼写和视觉形式加工方面的差异是否会导致后者的异常激活特征。第三个目标是评估这样一种假设，即观察到的左侧顶叶区域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，这可能是与阅读障碍相关的许多认知缺陷的基础。除了上述目标外，我们还将使用额外的统计分析来调查注意缺陷对激活特征的可能贡献及其差异。最后，利用脑磁图的激活轮廓是(A)为个体计算的，(B)具有极好的时间分辨率的特点，我们将探索通过使用模糊聚类技术来揭示正常儿童和阅读障碍儿童轮廓中细微差别的可能性。在未来的研究中，个体轮廓的时空特征的详细描述可能有助于评估干预策略对个体阅读障碍儿童功能性脑重组的影响。

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.