Role of left inferior frontal gyrus in the processing of particles in Japanese.

Particles are a crucial component of sentences in Japanese. They mainly follow nouns, and indicate their thematic role in the sentence, such as agent or patient. This study used functional MRI to investigate the neural basis of the processing of particles. We compared brain activity when participants were required to judge whether a presented character was a particle or whether the character as spoken ended with a specific vowel sound. Differential brain activity during particle judgment was found only in the left inferior frontal gyrus. We further confirmed that this activity was not a feature of categorical judgments in general. Our results indicate that the left inferior frontal gyrus is involved in the processing of thematic role indicated by Japanese particles.