Researchers: Two Separate Systems Control Human Movements（在线收听）

Great thinkers have considered the link between the human mind and body for thousands of years. This point of connection was the subject of recent research that appeared in Nature, a top science publication.

The researchers reported that they have discovered two separate systems in the brain that control the human motor system.

These systems are in parts of the brain area called the motor cortex. The motor cortex is a part of the brain's outermost layer, the cerebral cortex.

Researchers said they found that parts of the motor cortex that govern body movement are connected with a network involved in thinking, planning, pain, control of organs, as well as blood pressure and heart rate.

Evan Gordon of the Washington University School of Medicine in St. Louis was the lead author of the study.

Gordon said that the researchers showed that the human motor system is not one unit. "Instead, we believe there are two separate systems that control movement," he explained.

One system, he said, is for "isolated movement of your hands, feet and face. This system is important, for example, for writing or speaking - movements that need to involve only the one body part."

The research identified a second system within the motor cortex that they named SCAN, short for somato-cognitive action network. Researchers documented its connections to brain areas known to help set goals and plan actions.

The SCAN is more important for whole body movements and "is more connected to high-level planning regions of your brain," Gordon said.

The findings detail the brain's mind-body connection.

Nico Dosenbach of the Washington University School of Medicine was the study's senior lead author.

"Modern neuroscience does not include any kind of mind-body dualism," he said. The SCAN finding provides more explanation, Dosenbach added, "for why 'the body' and 'the mind' aren't separate or separable."

The researchers used modern brain-imaging techniques to test an important map established ninety years ago by brain surgeon Wilder Penfield. Their findings showed that Penfield's map, limited by the technologies of his time, needed changes.

Researchers identified SCAN by using special imaging in seven adults. They then checked their findings against larger datasets that included thousands of adults. Further imaging identified the SCAN circuit in an 11-month-old and a 9-year-old, while finding it had not yet formed in a newborn.

Those observations were supported in larger datasets of hundreds of newborns and thousands of 9-year-olds.

The research showed how much more there is to learn about the human brain.

Gordon said, "the purpose of the brain is highly debated."

He explained that some experts think of the brain as an organ intended mainly to perceive and interpret the world around us.

On the other hand, Gordon explained, other experts think of the "brain as an organ designed to produce the best 'outputs' - usually a physical action - to optimize survivability and evolutionary fitness for any given situation."

Gordon suggested that both views are probably correct. Still, he said, "The SCAN fits most cleanly with the latter interpretation: it integrates goals and planning with whole-body actions."

Words in This Story

author – n. a person who has contributed to some part of a research paper and either wrote or revised part of the research paper

region – n. a part of a country, of the world, etc., that is different or separate from other parts in some way

interpret – v. to understand (something) in a specified way

optimize – v. to make (something) as good or as effective as possible

evolutionary – adj. describes the process by which changes in plants and animals happen over time