Directly testing the magnocellular theory of dyslexia

摘要 该项目的目标是通过测量阅读障碍的大细胞理论（MTD）， 丘脑中大细胞（M）系统的功能。阅读障碍是一种特殊的阅读障碍， 影响了5%的人口。MTD是一个著名但有争议的理论，它提出， 阅读障碍的行为缺陷是大脑中M系统功能障碍的结果， 专门处理瞬时信息。因为M系统不能被孤立 在行为上，由于M流与皮层中的其他流混合，MTD 从来没有经过适当的测试。然而，M系统在感觉中仍然是空间分离的。 丘脑的核团因此，MTD将使用高分辨率功能磁共振成像仪进行测试。 磁共振成像（fMRI），以测量丘脑功能的三个独立的目标： 1.外侧膝状体核和丘脑网状核的时间信息加工 (TRN)阅读障碍正常吗 2.阅读障碍患者内侧膝状体核（MGN）的M部分功能正常吗？ 3.阅读障碍患者注意是否正常调节LGN、MGN和TRN？ 在目标1和2中，测量MGN和LGN中的M个系统将确定M 功能障碍，如果存在的话，是一个一般性质的大脑在诵读困难，或是否它是局限于一个单一的 感觉系统丘脑的主要功能之一是控制注意力，Aim 3将测试 是否注意力缺陷，已报告的阅读障碍是具体的M系统。 这些实验一起提供了一个全面的测试MTD，并将有助于解决其有效性。 这将对阅读障碍的认识和治疗产生重要影响。 这个项目将使用简单的刺激和实验设计的组合， 实验和分析技术，已被证明在我们的实验室能够可靠地检查 小而嘈杂的皮质下核，包括：高分辨率功能磁共振成像;大规模平均高， 分辨率质子密度加权图像，可以解决皮层下的解剖边界 核团;时间反应和视网膜定位与色调定位的群体感受野模型 组织;以及数据驱动的过滤和聚类。 该项目的结果将提供一个前所未有的直接测试，最终将解决 MTD的合法性。这将有助于指导未来资源的分配， 治疗阅读障碍

Abstract The goal of this project is to directly test the magnocellular theory of dyslexia (MTD) by measuring the function of the magnocellular (M) system in the thalamus. Dyslexia is a reading specific disorder that affects 5% of the population. The MTD is a prominent but controversial theory that proposes that the behavioral deficits in dyslexia are a consequence of the dysfunction of the M system in the brain, which is specialized for the processing of transient information. Because the M system cannot be isolated behaviorally, and because the M stream becomes intermixed with other streams in the cortex, the MTD has never been properly tested. However, the M system remains spatially segregated in the sensory nuclei in the thalamus. Therefore, the MTD will be tested using high-resolution functional magnetic resonance imaging (fMRI) to measure thalamic function in each of three independent aims: 1. Is temporal processing in the lateral geniculate nucleus (LGN) and thalamic reticular nucleus (TRN) normal in dyslexia? 2. Does the M portion of the medial geniculate nucleus (MGN) function normally in dyslexia? 3. Does attention modulate the LGN, MGN and TRN normally in dyslexia? In Aims 1 and 2, measuring the M systems in the MGN and LGN will determine whether M dysfunction, if present, is a general property of the brain in dyslexia, or whether it is confined to a single sensory system. One of the primary functions of the thalamus is to control attention, and Aim 3 will test whether the attentional deficits that have been reported in dyslexia are specific to the M system. Together these experiments provide a comprehensive test of MTD and will serve to resolve its validity. which will have an important impact on the understanding and treatment of dyslexia. This project will use a combination of simple stimuli and experimental designs with experimental and analytical techniques that have been proven in our lab to be able to reliably examine the small and noisy subcortical nuclei, including: high-resolution fMRI; massively averaged high- resolution proton-density weighted images that can resolve the anatomical boundaries of the subcortical nuclei; population receptive field modeling of temporal responses and retinotopic and tonotopic organization; and data-driven filtering and clustering. The results of this project will provide an unprecedented direct test that will ultimately settle the legitimacy of the MTD. This will help guide the allocation of future resources in understanding and treating dyslexia.