[论文解读] Reduced structural connectivity between left auditory thalamus and the motion-sensitive planum temporale in developmental dyslexia

Nadja Tschentscher, Anja Ruisinger+3 more|arXiv (Cornell University)|Nov 28, 2018

Reading and Literacy Development参考文献 78被引用 4

一句话总结

本研究利用扩散张量成像（DTI）结合概率追踪方法，探究了发展性阅读障碍患者左听觉丘脑（内侧膝状体，MGB）与运动敏感型颞平面（mPT）之间的结构连接性。研究发现，阅读障碍男性患者的连接性显著降低，支持了听觉处理中丘脑皮层功能障碍的假说，但mPT-MGB连接性与阅读障碍者的快速命名分数无相关性——仅在神经发育正常者中存在相关性。

ABSTRACT

Developmental dyslexia is characterized by the inability to acquire typical reading and writing skills. Dyslexia has been frequently linked to cerebral cortex alterations; however recent evidence also points towards sensory thalamus dysfunctions: dyslexics showed reduced responses in the left auditory thalamus (medial geniculate body, MGB) during speech processing in contrast to neurotypical readers. In addition, in the visual modality, dyslexics have reduced structural connectivity between the left visual thalamus (lateral geniculate nucleus, LGN) and V5/MT, a cerebral cortex region involved in visual movement processing. Higher LGN-V5/MT connectivity in dyslexics was associated with the faster rapid naming of letters and numbers (RANln), a measure that is highly correlated with reading proficiency. We here tested two hypotheses that were directly derived from these previous findings. First, we tested the hypothesis that dyslexics have reduced structural connectivity between the left MGB and the auditory motion-sensitive part of the left planum temporale (mPT). Second, we hypothesized that the amount of left mPT-MGB connectivity correlates with dyslexics RANln scores. Using diffusion tensor imaging based probabilistic tracking we show that male adults with developmental dyslexia have reduced structural connectivity between the left MGB and the left mPT, confirming the first hypothesis. Stronger left mPT-MGB connectivity was not associated with faster RANnl scores in dyslexics, but in neurotypical readers. Our findings provide first evidence that reduced cortico-thalamic connectivity in the auditory modality is a feature of developmental dyslexia, and that it may also impact on reading related cognitive abilities in neurotypical readers.

研究动机与目标

• 检验发展性阅读障碍个体在左听觉丘脑（MGB）与运动敏感型颞平面（mPT）之间是否存在结构连接性降低。
• 检验左MGB-mPT连接强度是否与快速自动命名（RANln）表现相关，后者是阅读能力的关键预测因子。
• 将先前关于阅读障碍中感觉性丘脑功能障碍的研究发现，从视觉模态扩展至听觉模态。
• 探究听觉通路中的丘脑皮层连接是否与阅读相关认知能力的个体差异有关。
• 确定MGB-mPT连接性与RANln的关系在阅读障碍者与神经发育正常者之间是否存在差异。

提出的方法

• 采用扩散张量成像（DTI）评估白质微结构与结构连接性。
• 应用概率追踪方法重建左MGB与左mPT之间的结构通路。
• 聚焦于患有发展性阅读障碍的成年男性与神经发育正常对照组，以最小化发育与性别相关的变异。
• 基于先前的功能神经影像学数据，将mPT定义为颞平面中对运动敏感的区域。
• 将连接强度量化为MGB与mPT之间重建通路沿线的平均部分各向异性（FA）。
• 比较阅读障碍者与神经发育正常读者的MGB-mPT连接性，并检验其与RANln表现的相关性。

实验结果

研究问题

• RQ1 发展性阅读障碍个体中，左听觉丘脑（MGB）与运动敏感型颞平面（mPT）之间的结构连接性是否降低？
• RQ2 发展性阅读障碍个体中，左MGB-mPT连接强度是否与快速命名（RANln）表现相关？
• RQ3 神经发育正常读者中，左MGB-mPT连接强度是否与RANln表现相关？
• RQ4 阅读障碍者与神经发育正常个体中，MGB-mPT连接性与RANln的关系是否存在差异？
• RQ5 阅读障碍者中MGB-mPT连接性降低是否支持听觉模态下发展性阅读障碍的丘脑皮层模型？

主要发现

• 与神经发育正常读者相比，患有发展性阅读障碍的成年男性在左MGB与左mPT之间的结构连接性显著降低。
• 在发展性阅读障碍个体中，左MGB-mPT连接强度与RANln表现无显著相关性。
• 相反，在神经发育正常读者中，更强的左MGB-mPT连接与更快的RANln表现显著相关。
• 本研究首次提供了发展性阅读障碍患者听觉通路中皮层-丘脑连接性减弱的证据。
• 研究结果提示，MGB-mPT连接性可能在阅读相关认知过程中发挥作用，尤其在神经发育正常个体中。
• 结果支持丘脑功能障碍在发展性阅读障碍中的更广泛作用，不仅限于视觉，也延伸至听觉感觉处理通路。