Recognition and reading aloud of kana and kanji word: an fMRI study

It has been proposed that different brain regions are recruited for processing two Japanese writing systems, namely, kanji (morphograms) and kana (syllabograms). However, this difference may depend upon what type of word was used and also on what type of task was performed. Using fMRI, we investigated brain activation for processing kanji and kana words with similar high familiarity in two tasks: word recognition and reading aloud. During both tasks, words and non-words were presented side by side, and the subjects were required to press a button corresponding to the real word in the word recognition task and were required to read aloud the real word in the reading aloud task. Brain activations were similar between kanji and kana during reading aloud task, whereas during word recognition task in which accurate identification and selection were required, kanji relative to kana activated regions of bilateral frontal, parietal and occipitotemporal cortices, all of which were related mainly to visual word-form analysis and visuospatial attention. Concerning the difference of brain activity between two tasks, differential activation was found only in the regions associated with task-specific sensorimotor processing for kana, whereas visuospatial attention network also showed greater activation during word recognition task than during reading aloud task for kanji. We conclude that the differences in brain activation between kanji and kana depend on the interaction between the script characteristics and the task demands.