1985 年 5 巻 2 号 p. 817-821
Two cases of alexia with agraphia limited to kanji letters who showed no signs of auditory language impairment including spontaneous speech and auditory comprehension were reported. In one case, CT scan of the brain revealed a low density area in the posterior portion of the left middle temporal gyrus. In the other lesions by CT were found in the anterior portion of the right temporal base and in the right occipital lobe (the patient is left handed). Also, a case of alexia with agraphia whose reading difficulty was limited to kana letters was quoted from the authors' previous report.
The existence of this double dissociation limited to letters, i. e. impaired kanji reading with preserved kana reading and impaired kana reading with preserved kanji reading strongly indicates that kanji and kana letters constitute two different semantic categories and have different neuropsychological organization.
Based on this experience of category specific alexia and on the experiences on Japanese aphasics in general, the authors presented a neuropsychological model of letter and word reading. In this model reading process is envisioned as a network structure.