Cognitive and neuroanatomical assessment of alexia and agraphia in Japanese: implications for the European languages.

The Japanese language has a unique writing system that consists of (morphograms, derived from Chinese characters) and (phonograms, a simplified form of kanji representing syllables). A kanji character has two distinct ways of reading: -reading (Chinese-style pronunciation) and -reading (native Japanese pronunciation). Some kanji words have irregular -reading called . Furthermore, kana characters have two script forms: (cursive form) and (square form), each of which is used for different purposes. Because of these features, Japanese individuals with alexia and agraphia show characteristic symptoms. Lesion-to-symptom analyses and functional imaging studies developed beginning in the 1970s have reported the following findings: (1) kanji-kana dissociation in alexia/agraphia: pure alexia for kanji or kana, lexical agraphia for kanji, and phonological agraphia for kana; (2) dissociation in alexia: predominant -reading and reading impairment in semantic dementia and selective -reading impairment in the extensive posterior middle temporal gyrus lesion; and (3) allographic agraphia between and .