Unified Brain Mechanisms Underlying the Processing of Word Order Permutations of Arguments and Adjuncts in Sentences

Human language often allows flexible word order in sentences with either an argument or an adjunct scrambled. This study examined brain mechanisms during the comprehension of such sentences in Japanese by conducting a functional magnetic resonance imaging (fMRI) experiment. The imaging results revealed that regardless of whether arguments or adjuncts undergo scrambling, the comprehension of noncanonical word order sentences yields a higher brain activation than their canonical counterparts. Specifically, the activation was found in the left inferior frontal gyrus and the posterior superior temporal sulcus. The current results lend neurological support for the canonical versus noncanonical word order distinction in sentences with adjuncts, suggesting a unified explanation for the brain mechanisms for the processing of word order permutation in human language.