Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.
Int J Neurosci. 2009;119(11):2017-43. doi: 10.1080/00207450903139671.
Dyslexia is primarily associated with a phonological processing deficit. However, the clinical manifestation also includes a reduced verbal working memory (WM) span. It is unclear whether this WM impairment is caused by the phonological deficit or a distinct WM deficit. The main aim of this study was to investigate neuronal activation related to phonological storage and rehearsal of serial order in WM in a sample of 13-year-old dyslexic children compared with age-matched nondyslexic children. A sequential verbal WM task with two tasks was used. In the Letter Probe task, the probe consisted of a single letter and the judgment was for the presence or absence of that letter in the prior sequence of six letters. In the Sequence Probe (SP) task, the probe consisted of all six letters and the judgment was for a match of their serial order with the temporal order in the prior sequence. Group analyses as well as single-subject analysis were performed with the statistical parametric mapping software SPM2. In the Letter Probe task, the dyslexic readers showed reduced activation in the left precentral gyrus (BA6) compared to control group. In the Sequence Probe task, the dyslexic readers showed reduced activation in the prefrontal cortex and the superior parietal cortex (BA7) compared to the control subjects. Our findings suggest that a verbal WM impairment in dyslexia involves an extended neural network including the prefrontal cortex and the superior parietal cortex. Reduced activation in the left BA6 in both the Letter Probe and Sequence Probe tasks may be caused by a deficit in phonological processing. However, reduced bilateral activation in the BA7 in the Sequence Probe task only could indicate a distinct working memory deficit in dyslexia associated with temporal order processing.
阅读障碍主要与语音处理缺陷有关。然而，临床表现还包括言语工作记忆（WM）跨度减小。目前尚不清楚这种 WM 损伤是由语音缺陷还是独特的 WM 缺陷引起的。本研究的主要目的是在 13 岁阅读障碍儿童样本中，与年龄匹配的非阅读障碍儿童相比，研究与 WM 中序列顺序的语音存储和复述相关的神经元激活。使用了具有两个任务的顺序言语 WM 任务。在字母探针任务中，探针由单个字母组成，判断是在前 6 个字母序列中是否存在该字母。在序列探针（SP）任务中，探针由所有 6 个字母组成，判断是其序列顺序与前序列中的时间顺序匹配。使用统计参数映射软件 SPM2 进行了组分析和单个受试者分析。在字母探针任务中，与对照组相比，阅读障碍者在左中央前回（BA6）的激活减少。在序列探针任务中，与对照组相比，阅读障碍者在额前皮质和顶叶上回（BA7）的激活减少。我们的研究结果表明，阅读障碍中的言语 WM 损伤涉及包括额前皮质和顶叶上回在内的扩展神经网络。在字母探针和序列探针任务中 BA6 的左侧激活减少可能是由于语音处理缺陷所致。然而，仅在序列探针任务中双侧 BA7 的激活减少可能表明阅读障碍与时间顺序处理相关的特定工作记忆缺陷。
