Left Frontal Lobe Damage with Dissociation between Romanized Japanese Spelling and Typing Abilities : A Case Study

Abstract

  Romanized Japanese words are Japanese words written in the Roman alphabet (e. g., water＝MIZU) . When Japanese people type Japanese words with a QWERTY keyboard, they usually type key sequences according to romanized Japanese spelling. We examined romanized Japanese spelling and typing abilities in a 73-year-old right-handed male patient with left frontal lobe damage and mild aphasia who could touch type pre-onset. In dictation tasks, we first asked him to write words and non-words in Kana, and also asked him to type them with a QWERTY keyboard. We found that he had difficulty in Kana writing, but could smoothly type the words and non-words. There were no differences in the scores between words and non-words in any task. Second, we asked him to spell out Japanese words in the Roman alphabet and found that he had difficulty in writing romanized Japanese words. In contrast, his typing ability was preserved. Generally, an inexperienced touch typist needs to refer to the Japanese syllable-Roman grapheme correspondence rule; when one becomes an expert at touch typing, Japanese mora directly associate with the corresponding key sequence movements (keystrokes) . The reason for preserved typing ability may be that this patient was a touch typist and had developed a Japanese mora-keystroke conversion system pre-onset. Brain regions outside the left frontal lobe (such as the left parietal lobe) may contribute to the Japanese mora-keystroke conversion system. Thus, the patient showed a dissociation between romanized Japanese spelling and typing abilities; the former was impaired but the latter was preserved.