Neural basis of the shift in grammatical subject: A functional magnetic resonance imaging study

Many researchers now consider language comprehension to be the generation of mental imagery of event structures. In addition, grammatical subjects are believed to correspond to the referents that initially capture attention in these visual events. Therefore, we hypothesized that mental imagery would be activated in sentence comprehension, with a central focus on the referent encoded as the grammatical subject. We performed two experiments using functional magnetic resonance imaging (fMRI), in which participants observed an event while focusing attention on a particular referent and then subsequently read a sentence describing it. In these experiments, visual attention was guided to a particular referent in a visual scene by a spatial cue. Based on our hypothesis, when the grammatical subject of a presented sentence was incongruent with the pre-attended referent, participants had to shift their attention to reactivate imagery of the event structure. On the other hand, this shift would not occur if the subject was congruent with the referent. In both the incongruent condition and in the opposite (congruent) condition , the right dorsolateral prefrontal cortex (DLPFC) was activated. This indicates that the right DLPFC was involved in this type of shifting process.