A new study has provided evidence representing literal linkage of body and mind in the very structure of the brain.
The study, which showed parts of the brain area controlling movement being plugged into networks involved in cognition, could help explain confounding behaviours such as resorting to pacing when feeling anxious and why people who exercise regularly report a more positive outlook on life.
These parts of the brain area were also found to control involuntary bodily functions such as blood pressure and heartbeat.
The study by researchers at Washington University School of Medicine in St. Louis, US, is published in the journal Nature.
"People who meditate say that by calming your body with, say, breathing exercises, you also calm your mind," said first author Evan M. Gordon, an assistant professor of radiology at the School of Medicine's Mallinckrodt Institute of Radiology.
These practices, while having been found useful such as in people with anxiety, have not been scientifically proved.
"But now we've found a connection. We've found the place where the highly active, goal-oriented 'go, go, go' part of your mind connects to the parts of the brain that control breathing and heart rate. If you calm one down, it absolutely should have feedback effects on the other."
Gordon and senior author Nico Dosenbach, an associate professor of neurology, had set out to verify the long-established map of the areas of the brain that control movement, using modern brain-imaging techniques by replicating Penfield's work with functional magnetic resonance imaging (fMRI).
A staple of neuroscience textbooks, Penfield's map of the motor regions of the brain were depicted as a homunculus, Latin for "little man". In the 1930s, neurosurgeon Wilder Penfield, MD, mapped such motor areas of the brain by applying small jolts of electricity to the exposed brains of people undergoing brain surgery, and noting their responses.
The research team built a high-density dataset by recruiting seven healthy adults to undergo hours of fMRI brain scanning while resting or performing tasks. They then built individualized brain maps for each participant.
Then, they validated their results using three large, publicly available fMRI datasets - the Human Connectome Project, the Adolescent Brain Cognitive Development Study and the UK Biobank - which together contained brain scans from about 50,000 people.
The team discovered, to their surprise, that Penfield's map wasn't quite right. Control of the feet was in the spot Penfield had identified. Same for the hands and the face.
However, interspersed with those three key areas were another three areas that did not seem to be directly involved in movement at all, even though they lay in the brain's motor area.
Moreover, the non-movement areas looked different than the movement areas. They appeared thinner and were strongly connected to each other and to other parts of the brain involved in thinking, planning, mental arousal, pain, and control of internal organs and functions such as blood pressure and heart rate.
Further imaging experiments showed that while the nonmovement areas did not become active during movement, they did become active when the person thought about moving.
Dosenbach and Gordon named their newly identified network the Somato (body)-Cognitive (mind) Action Network, or SCAN.
To understand how the network developed and evolved, they scanned the brains of a newborn, a 1-year-old and a 9-year-old. They also analyzed data that had been previously collected on nine monkeys.
The network was not detectable in the newborn, but it was clearly evident in the 1-year-old and nearly adult-like in the 9-year-old. The monkeys had a smaller, more rudimentary system without the extensive connections seen in humans.