Neuropediatrics 2006; 37 - TP101
DOI: 10.1055/s-2006-945694

THE READING ABILITY AND THE PHONOLOGICAL AWARENESS IN JAPANESE DYSLEXIC CHILDREN

A Seki 1, T Koeda 1, K Kassai 1
  • 1Division of Child Neurology, Tottori University Hospital, Yonago, Tottori, Japan

Objectives: In alphabetic languages, it is widely agreed that the phonological awareness deficit is the core deficit of developmental dyslexia. Their disrupted neural response to the phonological processing has been revealed by neuroimaging studies. However, it hasn't been clarified whether Japanese dyslexia shares this fundamental deficit. To discuss this question, we made and used the phonological awareness task comparable to English.

Methods: We made the Japanese letter rhyming task resemble the task used in English. To validate comparability of the task, we performed the functional MRI study using this task. Then, this task was used for the Japanese dyslexics and age-matched normal readers (7–12 years old). Their intelligence were measured by WISC-, and 15 dyslexics and 15 normal readers, who had 85–115 in PIQ, were included for the analysis. Two other Japanese phonological tasks, the Mora counting and the word reversal, were also performed. Their reading ability was evaluated by the reading speed, the reading errors, and the number of pauses while reading sentences aloud. The stepwise multi-regression analysis was used to determine which phonological abilities were more responsible for reading ability.

Results: By the fMRI, activation in the left inferior frontal and left inferior parietal gyrus were found, which was similar to the result of the English letter rhyming task. The performances of all phonological tasks were significantly worse in the dyslexic group. The stepwise multiple-regression analyses showed that the reading speed and the numbers of pauses were mostly explained by the performance of the letter rhyming task. The reading error was explained by the performances of the word reversal and the letter rhyming task.

Conclusion: The result shows that Japanese dyslexia shares the fundamental deficits in phonological awareness. The Japanese letter rhyming task strongly relates to the reading ability, and is useful to reveal the brain dysfunction of Japanese dyslexia.