Conversation Sparks Mirrored Brain Activity

Study Finds Similar Brain Activity in Speaker/Listener Pairs

July 26, 2010 -- Verbal communication is conveyed from speakers to listeners in a kind of mild melding brain process -- call it a meeting of the minds -- that facilitates understanding of what’s being said, a new study suggests.
Princeton University researchers using functional magnetic resonance imaging (fMRI) looked at brain activity in 12 native-English listeners, listening native-English speakers, and a native-Russian speaker in several experiments.
They found that brain activity in speaker/listener pairs was similar, and that the same regions “lit up” in the storyteller and the listeners. Put in terms of the researchers, neural coupling occurred, and that’s what underlies successful communicating, physicist and lead author Greg J. Stephens, PhD, of Princeton, tells WebMD.
The article says that the “similarity in the response patterns across all listeners underscores a strong tendency to process incoming verbal information in similar ways.”

The Study

The researchers performed the brain scans on a communicator and the listeners, first when a speaker told a long, unrehearsed story. Then the speaker told a new, unrehearsed 15-minute story about an experience that occurred years before. The same procedure was then used with a Russian speaker.
“If you speak in terms listeners don’t understand, there is very little neural coupling,” Stephens tells WebMD. “It extends only to low order auditory areas. They hear Russian but don’t do anything with it.”
When the speaking was in Russian, the results were starkly different -- brain regions that showed activity when listening to stories did not activate similarly in talkers and listeners, indicating that participants were not able to “extract the information” when dialogue was spoken in a foreign tongue, Stephens says.
He says the researchers conclude that “coupling” among people involved in a dialogue emerges only in a shared conversation, that is, when the same language is being spoken.
Also, in most brain regions of study participants, the activity in the listeners’ brains lagged activity in the speaker’s brain by one to three seconds, the authors write.

Neural Coupling

"It’s true that if you look, on average, across the brain, the listener’s activity is delayed relative to the speaker,” Stephens tells WebMD. “This makes sense. It takes time to process incoming information.”
However, he adds, “when you look more closely at the dynamic processes, there appear to be segregated regions that respond at the same time. Many respond in a delayed fashion and strikingly some respond in a predictive fashion.”
He says the study suggests that the stronger the neural coupling between people taking part in a conversation, the better the communication.
The study “also identifies a subset of brain regions in which the activity in the listener’s brain precedes the activity in the speaker’s brain,” the authors write. “The listener’s anticipatory responses were localized to areas known to be involved in predictions and value representation.”
The researchers say these anticipatory responses may provide listeners more time to process what they hear and more time to comprehend involves an element of prediction.
Stephens tells WebMD that “this works because the speaker’s brain is similar to the listener’s brain. We are using the same architecture. It makes sense that we use our own brain to predict what another person is saying.”
“For the most part, in neuroscience, neural systems and human brains are studied in isolation from each other,” Stephens tells WebMD. “What we’re showing, I think, is there is strong benefit to be gained when we relax the constraints. It matters a lot how we interact with others. We should look at this interaction closely and we’re likely to learn a lot.”
The study is published in the July 2010 issue of the Proceedings of the National Academy of Sciences.