Laycock Robin, Crewther Sheila G, Kiely Patricia M, Crewther David P
School of Psychological Science, La Trobe University, Bundoora, Victoria, 3086, Australia.
Behav Brain Funct. 2006 Aug 1;2:26. doi: 10.1186/1744-9081-2-26.
While there are many psychophysical reports of impaired magnocellular pathway function in developmental dyslexia (DD), few have investigated parietal function, the major projection of this pathway, in good and poor readers closely matched for nonverbal intelligence. In view of new feedforward-feedback theories of visual processing, impaired magnocellular function raises the question of whether all visually-driven functions or only those associated with parietal cortex functions are equally impaired and if so, whether parietal performance is more closely related to general ability levels than reading ability.
Reading accuracy and performance on psychophysical tasks purported to selectively activate parietal cortex such as motion sensitivity, attentional tracking, and spatial localization was compared in 17 children with DD, 16 younger reading-age matched (RA) control children, and 46 good readers of similar chronological-age (CA) divided into CA-HighIQ and a CA-LowIQ matched to DD group nonverbal IQ.
In the age-matched groups no significant differences were found between DD and CA controls on any of the tasks relating to parietal function, although performance of the DD group and their nonverbal IQ scores was always lower. As expected, CA and RA group comparisons indicated purported parietal functioning improves with age. No difference in performance was seen on any of the parietally driven tasks between the DD and age-nonverbal IQ matched groups, whereas performance differentiated the DD group from the age-matched, higher nonverbal IQ group on several such tasks. An unexpected statistical difference in performance between lower reading age (DD and RA children) and all higher reading age (CA) children was seen on a test of chromatic sensitivity, whereas when high and low nonverbal IQ normal readers were compared performance was not different
The results indicate that performance on purported parietal functions improves with age and may be more associated with nonverbal mentation than reading accuracy. Performance on a cognitively demanding task, traditionally considered to rely on ventral stream functions, was more related to reading accuracy.
虽然有许多关于发育性阅读障碍（DD）中大细胞通路功能受损的心理物理学报告，但很少有人研究顶叶功能，即该通路的主要投射，在非言语智力匹配的阅读能力强和弱的读者中的情况。鉴于视觉处理的新前馈-反馈理论，大细胞功能受损引发了这样一个问题：是否所有视觉驱动的功能，或者仅仅是那些与顶叶皮质功能相关的功能，都同样受损；如果是这样，顶叶表现是否与一般能力水平的关系比与阅读能力的关系更密切。
比较了17名患有DD的儿童、16名阅读年龄匹配（RA）的对照儿童以及46名年龄相仿（CA）的阅读能力强的儿童在阅读准确性和心理物理学任务上的表现，后者被分为CA-高智商组和CA-低智商组，其非言语智商与DD组匹配。这些心理物理学任务旨在选择性地激活顶叶皮质，如运动敏感性、注意力跟踪和空间定位。
在年龄匹配的组中，在与顶叶功能相关的任何任务上，DD组和CA对照组之间均未发现显著差异，尽管DD组的表现及其非言语智商分数始终较低。正如预期的那样，CA组和RA组的比较表明，所谓的顶叶功能随着年龄的增长而改善。在DD组和年龄-非言语智商匹配组之间，在任何由顶叶驱动的任务上均未观察到表现差异，而在几个这样的任务上，DD组与年龄匹配、非言语智商较高的组在表现上有所不同。在一项颜色敏感性测试中，较低阅读年龄（DD和RA儿童）与所有较高阅读年龄（CA）儿童之间的表现出现了意外的统计学差异，而在比较高和低非言语智商的正常读者时，表现并无差异。
结果表明，所谓顶叶功能的表现随着年龄的增长而改善，并且可能与非言语思维的关系比与阅读准确性的关系更密切。在一项传统上被认为依赖腹侧流功能的认知要求较高的任务上的表现，与阅读准确性的关系更为密切。
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