Processing of Anomalous Sentences in Japanese: An fMRI Study

Abstract

Most previous ncuroimaging studies of anomalous sentence processing have used Indo-Huropean languages to separately identify syntactic and semantic processing mechanisms. However, typologically distant languages such as Japanese use different sources of information in grammatical role assignments. Thus, we expected that the activation pattern during processing of anomalous sentences in Japanese would be at least partially different from that in other languages reported in previous studies. We used functional magnetic resonance imaging (fMRI) to measure activation during judgments of the correctness of normal and anomalous sentences in native Japanese speakers. We presented simple Japanese sentences as auditory stimuli. Significant activation was found in the left middle and inferior frontal regions (pars orbitaris and pars triangularis) and the superior parietal lobule during processing of sentences with semantic violations. On the other hand, no preferential activation was found, except for the left anterior part of the superior temporal gyrus, during the processing of sentences with syntactic violations. Additionally, activation in the left inferior frontal gyrus, which has been reported in previous studies using Indo-European languages, was not found in our study. The results support our assumption that the left inferior frontal gyrus plays a minor role in syntactic processing of simple Japanese sentences.