Investigating the role of the cerebellum in reading

摘要 发展性阅读障碍的主流理论认为，潜在的障碍是由以下因素引起的： 大脑皮层功能紊乱同样，努力理解阅读的神经基础 发展主要集中在大脑皮层。然而，由于主流理论 阅读障碍没有捕捉到其完整的行为表型，一直在继续考虑 对阅读发展和阅读障碍的神经基础的不同观点。当前 一项提案评估了这样一种替代理论，即“小脑缺陷假说”， 尼科尔森和他的同事们。我们提出了这个假设的一个变体，它来自于一个元分析。 阅读文献综述，CDH* 模型。在CDH* 模型中，梭状-顶叶-额叶 （背侧）通路支持对不熟悉的印刷单词的解码，小脑连接到 这条通路提高了顶叶和额叶之间的代表相似性。这 增加了一个给定的项目将被成功解码的可能性，从而导致正字法 学习一条腹侧连接的小脑-大脑回路，涉及梭状-颞-额 路径在解码过程中提供词汇语义约束，起到辅助作用 要求很高。我们研究了CDH* 模型在三个目标，涉及功能磁 成人受试者的共振成像和行为研究，以及正字法学习的使用 从基于项目（而不是基于阶段）的角度研究阅读发展的协议。在 目的1，我们研究成人阅读字印刷在一个新的学习人工正字法，并测试 小脑-大脑连接、表征相似性、解码之间的预测关系 成功，和正字法学习，以及语音要求对这些关系的影响。在 目的2，我们将测试是否有阅读障碍和没有阅读障碍的个体在小脑- 大脑连接性可以解释有效连接性，解码能力， 和正字法学习。在目标3中，我们将使用损伤方法来检验因果关系 后天性小脑损伤与解码和正字法学习障碍之间的联系。通过 推进目前对小脑--大脑的核心学习系统之一-- 与大脑阅读网络的接口，这项工作有可能广泛影响的理论， 阅读发展与阅读障碍。

ABSTRACT The predominant theories of developmental dyslexia view the underlying disorder as arising from dysfunction in the cerebral cortex. Similarly, efforts to understand the neural basis of reading development have focused largely upon the cerebral cortex. However, because predominant theories of dyslexia do not capture its full behavioral phenotype, there has been continued consideration of alternative perspectives on the neural substrates of reading development and dyslexia. The current proposal evaluates one such alternative theory, the “cerebellar deficit hypothesis” proposed by Nicolson and colleagues. We propose a variant of this hypothesis that arose from a meta-analytic review of the reading literature, the CDH* model. In the CDH* model, a fusiform-parietal-frontal (dorsal) pathway supports the decoding of unfamiliar printed words, with cerebellar connectivity into this pathway improving the representational similarity between the parietal and frontal nodes. This increases the likelihood that a given item will be decoded successfully, and thus induce orthographic learning. A ventrally connected cerebellar-cerebral circuit involving a fusiform-temporal-frontal pathway is proposed to play an assistive role, by providing lexical-semantic constraints when decoding demands are high. We investigate the CDH* model across three aims involving functional magnetic resonance imaging and behavioral studies in adult subjects, and the use of orthographic learning protocols to study reading development from an item-based (rather than stage-based) perspective. In Aim 1, we study adults reading words printed in a newly learned artificial orthography, and test for predicted relationships between cerebellar-cerebral connectivity, representational similarity, decoding success, and orthographic learning, and the impact of phonological demands on these relationships. In Aim 2, we will test whether individuals with and without dyslexia have differences in cerebellar- cerebral connectivity that can account for group differences in effective connectivity, decoding ability, and orthographic learning. In Aim 3, we will use the lesion method to test for a causal relationship between acquired cerebellar damage and impairments in decoding and orthographic learning. By advancing current understanding of how the cerebellum – one of the brain's core learning systems – interfaces with a cerebral reading network, the work has the potential to widely influence theories of reading development and dyslexia.