Cao Fan, Yan Xin, Spray Gregory J, Liu Yanni, Deng Yuan
Department of Psychology, Sun Yat-sen University, Guangzhou, China.
Department of Communicative Sciences and Disorders, Michigan State University, East Lansing, MI, United States.
Front Hum Neurosci. 2018 Dec 6;12:490. doi: 10.3389/fnhum.2018.00490. eCollection 2018.
Multiple hypotheses have been proposed to explain the reading difficulty caused by developmental dyslexia (DD). The current study examined visuo-orthographic processing in children with dyslexia to determine whether orthographic deficits are explainable based solely on visual deficits. To identify orthographic-specific, visual perception-specific, and overlapping deficits, we included two tasks (lexical and perceptual) in three Chinese subject groups: children with DD, age-matched controls (AC), and reading matched controls (RC) using functional magnetic resonance imaging (fMRI). We found that the left precuneus showed decreased activation across both tasks for the DD group compared to the two control groups, thus reflecting visual processing deficits in children with DD, which also affects orthographic processing. Furthermore, we found that the functional connectivity between left middle occipital gyrus (LMOG) and left inferior frontal gyrus (IFG) was decreased in the DD group compared to AC and RC for only the lexical task. This suggests a weaker association between orthography and phonology for children with DD. In addition, the children with DD showed decreased functional connectivity between the LMOG and right parahippocampal gyrus for only the visual perceptual task, thereby indicating a weaker association between visual regions for DD during visual symbol processing. Taken together, our findings suggest that the observed orthographic processing deficit in DD might be driven by both a basic visual deficit, and a linguistic deficit.
人们已经提出了多种假设来解释发育性阅读障碍（DD）所导致的阅读困难。本研究对患有阅读障碍的儿童的视觉正字法加工进行了检查，以确定正字法缺陷是否仅基于视觉缺陷就能得到解释。为了识别正字法特异性、视觉感知特异性和重叠性缺陷，我们在三个中文受试组中纳入了两项任务（词汇和感知）：患有DD的儿童、年龄匹配的对照组（AC）以及阅读匹配的对照组（RC），并使用功能磁共振成像（fMRI）。我们发现，与两个对照组相比，DD组在两项任务中左侧楔前叶的激活均减少，这反映了患有DD的儿童存在视觉加工缺陷，而这也会影响正字法加工。此外，我们发现，仅在词汇任务中，与AC组和RC组相比，DD组左侧枕中回（LMOG）和左侧额下回（IFG）之间的功能连接减少。这表明患有DD的儿童在正字法和语音之间的关联较弱。此外，患有DD的儿童仅在视觉感知任务中LMOG和右侧海马旁回之间的功能连接减少，从而表明在视觉符号加工过程中，DD患者视觉区域之间的关联较弱。综上所述，我们的研究结果表明，在DD中观察到的正字法加工缺陷可能是由基本视觉缺陷和语言缺陷共同导致的。
