Preservation of non — phonological writing systems for kana and typing systems for Roman characters in a Japanese aphasic patient

Abstract

  Writing and typing abilities of a 57-year-old, right-handed Japanese patient with aphasia due to cerebral infarction were investigated. Writing was comparatively preserved when the patient used kanji. In kana, however, he showed a salient deficit in writing a single kana and a non-existent, two-mola kana word to dictation even though a substantial number of kana words could be produced both spontaneously and to dictation. Similarly a number of phonetic values for kanji were written in kana correctly. Semantic paragraphias were observed in writing both kana and kanji words to dictation. Unsuitably selected phonetic values for kanji were also produced in kana without orthographic errors. It was suggested that his abilities to write kana were dependent on the semantic processor and that kinesthetic images of characters were recruited by way of the semantic-visuomorphographic-kinesthetic route and⁄or the semantic-kinesthetic route. Although writing single kana and Roman characters to dictation as well as reading them aloud showed poor performance, written conversion from kana to Roman characters and vice versa was preserved. Such written conversion was presumed to be processed within the visuomorphographic processor of characters. We concluded that the non-phonological kana writing system was based on the predominance of the semantic, visuomorphographic and kinesthetic processors rather than the route via the phonological processor. Furthermore, it was suggested that such non-phonological processors played an important role in his typing of Roman characters as well.