Developmental dyscalculia: compensatory mechanisms in left intraparietal regions in response to nonsymbolic magnitudes
Developmental dyscalculia: compensatory mechanisms in left intraparietal regions in response to nonsymbolic magnitudes
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DOI：
10.1186/1744-9081-5-35
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发表时间：
2009-08-05
影响因子：
5.1
通讯作者：
Wood, Guilherme
中科院分区：
文献类型：
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作者：
Kaufmann, Liane;Vogel, Stephan E.;Wood, Guilherme
背景：关于发育性计算障碍的神经机制的功能性磁共振成像（fMRI）研究很少，结果至今尚无定论。本研究的主要目的是探讨有和无计算障碍儿童非符号数量级加工的神经关联。方法：对18名患有计算障碍的儿童（其中9名患有计算障碍）进行脑扫描，要求他们完成一项非符号数量级比较任务（手指图案）。对于空间控制任务，使用相同的刺激，指令只有变化（判断手掌旋转）。这种设计使我们能够在实验和控制任务中呈现具有相同视觉处理要求的相同刺激。此外，由于数字和空间处理依赖于顶叶脑区，任务特异性对比有望揭示真正的数字特异性激活。结果：扫描期间的行为结果显示，尽管表现水平相当（几乎在天花板上），但计算障碍儿童在双侧顶叶下皮层（顶叶内沟、边缘上回、延伸到左角回）的任务特异性激活更强。有趣的是，fMRI信号强度反映了组x任务的相互作用：相对于基线，对照组在对数字处理而不是空间处理的反应中产生了显著的双侧顶叶区域失活，而在计算障碍中出现了相反的模式。此外，对数字处理反应的beta权重在两组之间的左顶叶区域显著不同，而在右顶叶区域（内顶叶区域）则没有（在计算困难的儿童中甚至变为正值）。结论：总的来说，研究结果表明：(a)在处理非符号数字量级时，右侧顶叶区域（顶内）的神经活动不一致；(b)发育性计算障碍左顶叶区域代偿性神经活动。
Background: Functional magnetic resonance imaging (fMRI) studies investigating the neural mechanisms underlying developmental dyscalculia are scarce and results are thus far inconclusive. Main aim of the present study is to investigate the neural correlates of nonsymbolic number magnitude processing in children with and without dyscalculia.Methods: 18 children (9 with dyscalculia) were asked to solve a non-symbolic number magnitude comparison task (finger patterns) during brain scanning. For the spatial control task identical stimuli were employed, instructions varying only (judgment of palm rotation). This design enabled us to present identical stimuli with identical visual processing requirements in the experimental and the control task. Moreover, because numerical and spatial processing relies on parietal brain regions, task-specific contrasts are expected to reveal true number-specific activations.Results: Behavioral results during scanning reveal that despite comparable (almost at ceiling) performance levels, task-specific activations were stronger in dyscalculic children in inferior parietal cortices bilaterally (intraparietal sulcus, supramarginal gyrus, extending to left angular gyrus). Interestingly, fMRI signal strengths reflected a group x task interaction: relative to baseline, controls produced significant deactivations in (intra) parietal regions bilaterally in response to number but not spatial processing, while the opposite pattern emerged in dyscalculics. Moreover, beta weights in response to number processing differed significantly between groups in left - but not right (intra) parietal regions (becoming even positive in dyscalculic children).Conclusion: Overall, findings are suggestive of (a) less consistent neural activity in right (intra) parietal regions upon processing nonsymbolic number magnitudes; and (b) compensatory neural activity in left (intra) parietal regions in developmental dyscalculia.