Two-Person MRI Scans Reveal What Happens In The Brain When Being Touched By Another Person

During a conversation or while solving a problem, brain functions become “flexibly linked with each other” but the real-time social interaction between two people. SpeedKingz/Shutterstock

Intimately touching another person signals a complex neural response in both persons' brains, according to new research published in the journal Frontiers in Psychiatry.

During a conversation or while solving a problem, brain functions become “flexibly linked with each other” but the real-time social interaction between two people and how the brain responds has not been widely studied. To determine how social interactions activate the brain, researchers at Aalto University and Turku PET Centre took a typical 32-channel head coil usually used in individual brain scans and divided it into two custom-built 16-channel helmets to simultaneously track what happens in two brains at the same time.  

Ten couples – seven female-male pairs and three female-female couples – who were either friends or romantic partners were outfitted with these specially designed brain coils, but were first scanned individually using the normal one-person setup. Each couple then spent 45 minutes inside the MRI scanner together positioned closely, face to face. When signaled by the researchers, study participants took turns tapping their partner’s lips to simulate touching each other in what the researchers describe as an “intimate way of conveying affection and trust in social relationships”.

Looking at the scans, the researchers could see that the motor and sensory regions of both brains were activated.

"During social interaction, people's brains are literally synchronized," said Professor Lauri Nummenmaa from Turku PET Centre in a statement. "The associated mental imitation of other people's movements is probably one of the basic mechanisms of social interaction. The new technology now developed will provide totally new opportunities for studying the brain mechanisms of social interaction."

Two people together in an MRI Scanner along with the accompanying image of their brains. Ville Renvall/ Aalto University

Human interactions are complex behaviors that require not only communication but the understanding of both verbal and nonverbal cues, and the emotional as well as cognitive information that they entail. Communicating with another person is “intertwined into a shared system facilitating reciprocation” that also requires the other person needs to anticipate what the other is saying and problem solve – both of which spur neural processing across the brain.

"This is an excellent start for the study of natural interaction. People don't just react to external stimuli, but adjust their actions moment-by-moment based on what they expect to happen next," said Riitta Hari, emerita Professor at Aalto University.

Normally, MRI capabilities are only able to scan one person at a time, a limitation in understanding how the human brain is impacted by social interactions. Though the new proof-of-concept design presented quality limitations when compared with the standard 32-channel head coils, its use still demonstrates that it is possible to study two brains at the same time.

Brain activation related to mutual touch

Normally, MRI capabilities are only able to scan one person at a time, a limitation in understanding how the human brain is impacted by social interactions. Though the new proof-of-concept design presented quality limitations when compared with the standard 32-channel head coils, its use still demonstrates that it is possible to study two brains at the same time.

 

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