The Scientific American has an item by R.D. Fields about the research of U. Hasson (here). It compares the activity in a listener compared to a speaker.
There have been many functional brain imaging studies involving language, but never before have researchers examined both the speaker’s and the listener’s brains while they are communicating to see what is happening inside each brain. The researchers found that when the two people communicate, neural activity over wide regions of their brains becomes almost synchronous, with the listener’s brain activity patterns mirroring those sweeping through the speaker’s brain, albeit with a short lag of about one second. If the listener, however, fails to comprehend what the speaker is trying to communicate, their brain patterns decouple…
(overcoming technical problems) He asked his student to tell an unrehearsed simple story while imaging her brain. Then they played back that story to several listeners and found that the listener’s brain patterns closely matched what was happening inside the speaker’s head as she told the story.
The better matched the listener’s brain patterns were with the speaker’s, the better the listener’s comprehension, as shown by a test given afterward… there is no mirroring of brain activity between two people’s brains when there is no effective communication (except for some regions where elementary aspects of sound are detected. When there is communication, large areas of brain activity become coupled between speaker and listener, including cortical areas involved in understanding the meaning and social aspects of the story.).
Interestingly, in part of the prefrontal cortex in the listener’s brain, the researchers found that neural activity preceded the activity that was about to occur in the speaker’s brain. This only happened when the speaker was fully comprehending the story and anticipating what the speaker would say next.
What an elegant demonstration of communication!