REVIEW article
Front. Hum. Neurosci.
Sec. Speech and Language
Volume 19 - 2025 | doi: 10.3389/fnhum.2025.1664803
Cognitive and neuroanatomical assessment of alexia and agraphia in Japanese: Implications for the European languages
Provisionally accepted
- Mitsui Memorial Hospital, Tokyo, Japan
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The Japanese language has a unique writing system that consists of kanji (morphograms, derived from Chinese characters) and kana (phonograms, a simplified form of kanji representing syllables). A kanji character has two distinct ways of reading: on-reading (Chinese-style pronunciation) and kun-reading (native Japanese pronunciation). Some kanji words have irregular kun-reading called jukujikun. Furthermore, kana characters have two script forms: hiragana (cursive form) and katakana (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) on-kun dissociation in alexia: predominant kun-reading and jukujikun reading impairment in semantic dementia and selective on-reading impairment in the extensive posterior middle temporal gyrus lesion; and (3) allographic agraphia between hiragana and katakana.
Keywords: kanji, Kana, Dual-route hypothesis, pure alexia, Alexia with agraphia
Received: 12 Jul 2025; Accepted: 18 Aug 2025.
Copyright: © 2025 Sakurai. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Yasuhisa Sakurai, Mitsui Memorial Hospital, Tokyo, Japan
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