The human brain with the central gyrus highlighted, the location of the motor cortex
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Our movements may not be controlled by just one network in our brain, but by two different networks.
For nearly a century, we’ve known that the motor cortex, a relatively thin strip of tissue in the center of the brain that spans both hemispheres, controls body movements.
In the 1930s, neuroscientists Wilder Penfield and Edwin Baldry electrically stimulated the brains of people undergoing neurosurgery and showed that different parts of the primary motor cortex control different parts of the body. showed. Also, these control regions are so-called homunculus, as shown in his map, with the body parts that these control regions point to, such as the toes at one end and the face at the other. I also found that they were arranged in the same order.
Evan Gordon and his colleagues at the University of Washington School of Medicine in Missouri wanted to use the latest technology to explore Penfield-Boldrey’s ideas in more detail. So they took high-resolution MRI scans of him from 12 hours to 15 hours of him lying down on the scanner and looking at the cross symbol.
According to Gordon, analyzing the brains when participants were mostly stationary and not engaged in a task such as reading made the brain activity data less complex, allowing researchers to see which parts of the brain worked together. You can now better observe what you are doing.
The Penfield-Boldrey study suggests that the primary motor cortex is composed of homunculus maps. However, Gordon and his team believe that the cerebral cortex also has three areas of his that are scattered throughout the map, and that work together to coordinate movements to body centers such as the shoulders and abdomen. I found that I can see
The researchers then scanned the brains of two of the participants again in an MRI scanner while they were lying down and performing 25 movements, such as blinking and swallowing.
These scans generally support the information outlined in the Homunculus Map. Simply put, they found that one area of his primary motor cortex is associated with lower body movements, one area is associated with hand movements, including the shoulders, and another area is associated with facial movements. indicates that This is consistent with what Penfield and Baldry have described and constitutes one of two distinct networks in the brain that control movement.
Homunculus map showing how different regions of the motor cortex control movements of different parts of the body
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From the scans of these two participants, the researchers showed in more detail the area between them on the homunculus map. These were especially active when moving the midsection.
The researchers named these intermediate regions the body-cognitive activity network (SCAN). This constitutes her second distinct network in our brain.
We then looked for signs of SCAN in brain activity data obtained from scans obtained from several major databases, such as the Human Connectome Project and the UK Biobank, and found that SCAN appeared to be present in all samples analyzed. discovered.
The SCAN network appears to work alongside the first network in the primary motor cortex, which controls movements related to the hands, feet, and mouth, says Gordon. Movements to other parts of the body, such as the hips and back, may be controlled by other areas of the motor cortex, he says.
In another part of the experiment, researchers scanned the brains of three children (newborn, 11 months, and 9 years old) to see if they had SCAN.
No networks were found in newborns, but were found in 11-month and 9-year-olds, suggesting that networks develop as babies grow. You can literally move your limbs,” says Gordon. “Newborns, on the other hand, have very little control over their own body movements.”
The team wonders whether SCAN may be involved in conditions such as Parkinson’s disease, which affect movement and cause symptoms such as tremors. Gordon said it could be a therapeutic target for other movement-related disorders such as dysentery and ataxia.
“This is a new contribution to a longstanding neuroscience question in neuroscience. [the] The motor cortex is used to control movement,” says Patrick Haggard of University College London. To validate these results, he says, it would be useful to record SCAN neurons in experiments where people or other animals are not confined to the scanner and can move freely.
