Parenting and Special Education Research Unit, KU Leuven, Belgium; Brain and Cognition Research Unit, KU Leuven, Belgium; Numerical Cognition Laboratory, Department of Psychology, Brain and Mind Institute, Western University, Canada.
Brain and Cognition Research Unit, KU Leuven, Belgium.
Neuroimage Clin. 2018 Mar 4;18:663-674. doi: 10.1016/j.nicl.2018.03.003. eCollection 2018.
Brain disorders are often investigated in isolation, but very different conclusions might be reached when studies directly contrast multiple disorders. Here, we illustrate this in the context of specific learning disorders, such as dyscalculia and dyslexia. While children with dyscalculia show deficits in arithmetic, children with dyslexia present with reading difficulties. Furthermore, the comorbidity between dyslexia and dyscalculia is surprisingly high. Different hypotheses have been proposed on the origin of these disorders (number processing deficits in dyscalculia, phonological deficits in dyslexia) but these have never been directly contrasted in one brain imaging study. Therefore, we compared the brain activity of children with dyslexia, children with dyscalculia, children with comorbid dyslexia/dyscalculia and healthy controls during arithmetic in a design that allowed us to disentangle various processes that might be associated with the specific or common neural origins of these learning disorders. Participants were 62 children aged 9 to 12, 39 of whom had been clinically diagnosed with a specific learning disorder (dyscalculia and/or dyslexia). All children underwent fMRI scanning while performing an arithmetic task in different formats (dot arrays, digits and number words). At the behavioral level, children with dyscalculia showed lower accuracy when subtracting dot arrays, and all children with learning disorders were slower in responding compared to typically developing children (especially in symbolic formats). However, at the neural level, analyses pointed towards substantial neural similarity between children with learning disorders: Control children demonstrated higher activation levels in frontal and parietal areas than the three groups of children with learning disorders, regardless of the disorder. A direct comparison between the groups of children with learning disorders revealed similar levels of neural activation throughout the brain across these groups. Multivariate subject generalization analyses were used to statistically test the degree of similarity, and confirmed that the neural activation patterns of children with dyslexia, dyscalculia and dyslexia/dyscalculia were highly similar in how they deviated from neural activation patterns in control children. Collectively, these results suggest that, despite differences at the behavioral level, the brain activity profiles of children with different learning disorders during arithmetic may be more similar than initially thought.
脑疾病通常是孤立地进行研究的，但当研究直接对比多种疾病时，可能会得出非常不同的结论。在这里，我们将在特定学习障碍（如计算障碍和阅读障碍）的背景下说明这一点。患有计算障碍的儿童在算术方面表现出缺陷，而患有阅读障碍的儿童则表现出阅读困难。此外，阅读障碍和计算障碍之间的共病率高得惊人。关于这些障碍的起源，已经提出了不同的假说（计算障碍中的数字处理缺陷，阅读障碍中的语音缺陷），但这些假说从未在一项脑成像研究中直接进行对比。因此，我们在一项设计中比较了阅读障碍、计算障碍、阅读障碍和计算障碍共病儿童以及健康对照组儿童在算术过程中的大脑活动，该设计使我们能够区分可能与这些学习障碍的特定或共同神经起源相关的各种过程。参与者为 62 名 9 至 12 岁的儿童，其中 39 名被临床诊断为特定学习障碍（计算障碍和/或阅读障碍）。所有儿童在执行不同格式（点数组、数字和数字单词）的算术任务时都接受了 fMRI 扫描。在行为水平上，计算障碍儿童在减去点数组时的准确率较低，所有学习障碍儿童的反应速度都比正常发育儿童慢（尤其是在符号格式下）。然而，在神经水平上，分析表明学习障碍儿童之间存在大量的神经相似性：无论障碍如何，对照组儿童在额叶和顶叶区域的激活水平均高于三组学习障碍儿童。对学习障碍儿童组之间的直接比较显示，这些组在整个大脑中的神经激活水平相似。多元主体概括分析用于统计测试相似程度，并证实了阅读障碍、计算障碍和阅读障碍/计算障碍儿童在如何偏离对照组儿童的神经激活模式方面，其神经激活模式高度相似。总的来说，这些结果表明，尽管在行为水平上存在差异，但在进行算术运算时，不同学习障碍儿童的大脑活动模式可能比最初想象的更为相似。
