2006 Volume 26 Issue 2 Pages 141-155
The ability to read or write is not biologically prepared but can be acquired only through instruction and adequate learning. Different neuronal networks may be organized according to the characteristics of different script systems. This cultural effect should be taken into account in order to analyze the symptoms of acquired dyslexia. Therefore, the theoretical framework of cognitive neuropsychology on reading disorders in Western language, as it stands, should not be applied to the symptomatology of acquired dyslexia in Japanese patients who employ unique writing systems. The most important difference between English and Japanese is the type of basic visual units in written language ; words in English vs letters in Japanese. The another striking feature is that Japanese speakers usually imagine letters when they communicate trough spoken language. Kana (syllabogram) letters represent abstract and highly categorized phonological symbols.
Two patients with aphasic alexia were reported, who produced a large number of semantic paralexias in reading aloud Kana words, as well as in Kanji (morphogram) words. The examination of 4 phonological dyslexics led us to conclude that underlying factors responsible for the impairment of oral reading of Kana nonwords are a disturbance in literal-to-phonological transcoding and a disorder in sequential processing, in addition to a general phonological impairment. A patient with word meaning deafness who could understand orthographically unfamiliar Kana words was reported. A hypothesis is presented that the refinement of phonological representation, from lower level to higher one, is disrupted in word meaning deafness.
