How to adjust movements by ignoring distracting information

Inhibitory neuronal cell bodies (red) in the brain stem and axon processes (green) to Kneate cells (blue) that transmit touch information. This circuit regulates the information transmitted by the touch receptors of the hand as it enters the brain. Credit: Salk Institute

As you read this article, the touch receptors on your skin sense the environment. Each touch activates a collection of nerve cells, even when clothes and jewelry, a sitting chair, your computer keyboard or mobile device, or your fingers unintentionally brush each other. However, the brain ignores many of these inputs unless the stimulus is particularly unexpected or necessary to direct its movements.

Now, Salk researchers are investigating how neurons in a small area of ​​the mammalian brain can help regulate dexterous movements, especially by filtering distracting and destructive signals from the hands. I found.Their results published in the journal Chemistry On October 14, 2021, we may hold a lesson on how the brain filters other sensory information.

“These findings are from our Nervous system It not only interacts with the world, but also teaches you how to build better prostheses and robots, and how to repair them more effectively. Neural circuit “After an illness or injury,” said Eiman Azim, an assistant professor at Salk’s Institute for Molecular Neurobiology and William Scandling Developmental Chair.

Scientists have long known that from throwing a ball to playing an instrument, hand input is needed to adjust dexterous movements. In one classic experiment, anesthetized, numb fingertip volunteers found it very difficult to pick up and light a match.

“There is a general misconception that the brain only sends signals and performs the resulting movements,” says Azim. “But in reality, the brain constantly takes in feedback information about the condition of the limbs and fingers and adjusts its output accordingly.”

When the brain responds to all signals from the body, it quickly overwhelms, as does with some sensory processing disorders. Azim and his colleagues wanted to pinpoint exactly how a healthy brain chooses and chooses. Tactile signal Take into account to coordinate dexterous movements such as manipulating objects.

They used a combination of mouse tools to study cells in a small area of ​​the brainstem called the Kneate nucleus, the first area where signals from the hand enter the brain. Although it was known that sensory information passes through the Kneate nucleus, the team actually controls the amount of information from the hand that is ultimately passed to other parts of the brain by a set of neurons in this area. I found that. By manipulating these circuits to allow more or less tactile feedback, Azim’s team rewards them by performing dexterous tasks such as mouse pulling ropes and learning to distinguish textures. Can influence the way you earn.

“Kneate nuclei are often referred to as relay stations, as if information were just passing through,” says staff researcher James Conner, the first author of the new treatise. “But it turns out that the sensory information is actually modulated by this structure.”

Connor and Azim also set out to determine how strongly different parts of the mouse cortex, the areas responsible for more complex and adaptive behavior, filter sensory information from the hands. We have shown how neurons can be controlled.

Today, despite decades of work, most prostheses and robots struggle to perform small, accurate hand movements with agile fingers. Azim and Conner say their work could help inform the design of better processes for integrating sensory information from artificial fingers into these types of systems to improve dexterity. Stated. It can also affect understanding sensory processing disorders and troubleshooting what goes wrong during brain flow. Sensory information The balance will be lost.

“The sensory systems have evolved to be very sensitive to maximize the protective response to external threats, but our own actions activate these sensory systems, thereby ours. It produces feedback signals that can confuse intended behavior, “says Connor.

“We are constantly being attacked by information from the world, and our brains need a way to determine what goes through and what doesn’t,” says Azim. “It’s not just tactile feedback, but sight and smell and hearing, temperature and pain. The lesson we’re learning about this circuit is in a general way. brain Adjust these types of feedback as well. ”

Unravel the mystery of touch: revealed a mechanism that may explain why certain body parts are so sensitive

For more information:
James Conner et al., Modulation of haptic feedback to perform dexterous movements, Chemistry (2021). DOI: 10.1126 / science.abh1123

Provided by
Salk Institute

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