Study on brain areas associated with writing Hiragana and Katakana using fMRI - Examination by written naming tasks and dictation study

Abstract

The Japanese written language comprises Kanji characters as well as two phonetic systems: Hiragana and Katakana. The aim of this study was to investigate brain areas associated with writing Hiragana and Katakana using functional magnetic resonance imaging (fMRI). Fourteen healthy participants described pictures (written naming) and transcribed dictation (dictation). The middle frontal, middle temporal, angular and supramarginal gyri were activated while completing the written naming task in Hiragana, whereas the angular and supramarginal gyri were activated during the corresponding task in Katakana. The superior, medial frontal and middle occipital gyri were activated during transcription of dictation in Hiragana, and the superior frontal, superior and middle occipital gyri were activated when transcribing dictation in Katakana. These results indicate that the areas of the brain involving writing of Hiragana and Katakana comprise a common phonological pathway. Furthermore, activation of the temporo-parietal area during the written naming task was associated with phoneme-to-grapheme conversion. By contrast, the visual association area was significantly activated while transcribing dictation in the absence of visual stimuli. This finding suggests that a representational image of a spoken word is imagined during dictation.