As a followup to Monday's post on mirror neurons, this fascinating study by Stephens et al. shows that brain activities in a speaker-listener pair are tightly coupled, and that the magnitude of activity in areas exhibiting predictive anticipatory responses correlates with understanding. The graphic summaries of fMRI data in this open access article are quite nice, and you might want to check them out. The MindBlog reader who pointed out this early PNAS publication to me wonders "Could their findings open a new window of how to interpret the "function" of "conscious self", with the conscious self as the evaluating "outpost" of the coupled companion.?"
Verbal communication is a joint activity; however, speech production and comprehension have primarily been analyzed as independent processes within the boundaries of individual brains. Here, we applied fMRI to record brain activity from both speakers and listeners during natural verbal communication. We used the speaker's spatiotemporal brain activity to model listeners’ brain activity and found that the speaker's activity is spatially and temporally coupled with the listener's activity. This coupling vanishes when participants fail to communicate. Moreover, though on average the listener's brain activity mirrors the speaker's activity with a delay, we also find areas that exhibit predictive anticipatory responses. We connected the extent of neural coupling to a quantitative measure of story comprehension and find that the greater the anticipatory speaker–listener coupling, the greater the understanding. We argue that the observed alignment of production- and comprehension-based processes serves as a mechanism by which brains convey information.