When a person presses on the temples or the back of the head to soothe a aching sensation in the head or rubs the elbow after bumping unexpectedly against a hard object, it often brings some relief.
According to what was published by the site “Neuroscience News”.Neuroscience NewsPain-sensing cells in the brain are thought to calm down when nerve cells are stroked.
A team of scientists from MIT’s McGovern Institute for Brain Research observed the phenomenon in the brains of mice for the first time.
The relationship between touch and pain
The researchers presented the results of their discovery, which was published in the journal Science Advances, which offers a deeper understanding of the complex relationship between pain and touch and may offer some insights into chronic pain in humans.
Fan Wang, a researcher at the McGovern Institute, says the reason for the interest in researching the phenomenon is due to the fact that it is a “common human experience”, explaining that “when one part of a person’s body hurts, automatically because he knows touch can relieve pain this way, but it was difficult for neuroscientists to study the case.
Pain relief modeling
Pain relief through touch may begin in the spinal cord, where previous studies have found pain-sensitive neurons whose signals weaken in response to touch. But there have been hints that there is also a cycle in the brain.
This aspect of response has been largely unexplored, Wang says, because it can be difficult to monitor the brain’s response to painful stimuli amid all the other neural activity going on there, especially when lab animals are moving around.
So while the team of researchers knew that mice respond to a potentially painful stimulus on their temples by rubbing their face with their paws, they couldn’t follow the specific pain response in the animals’ brains to see if this rubbing helped calm them down. down.
rhythmic movement
But Wang says she and her colleagues have found a way around this obstacle: Instead of studying the effects of face rubbing, they focused their attention on a more subtle form of touch: the gentle vibrations produced by the movement of animals’ whiskers. .
Mice use their whiskers to explore, moving them back and forth in a rhythmic motion known as flapping to feel their surroundings. This movement activates the touch receptors in the face and sends information to the brain in the form of vibration signals.
The human brain receives the same type of tactile signal when a person holds their other hand as it is pulled from a painfully hot frying pan. Another way a person seeks pain relief is through touch.
Get rid of the pain
Wang and his colleagues found that whisker movement can change how mice respond to a nuisance heat or a blow to the face, both of which normally result in facial rubbing.
“Cells that respond preferentially to heat and pressure are less activated when rats pet themselves, as they are less likely to show responses to painful stimuli,” Wang says.
Even when the fussing animals rubbed their faces in response to painful stimuli, the team of researchers found that neurons in the brain took longer to adopt the pain-relieving patterns associated with friction and touch movement.
Thalamic pain syndrome
Wang points out that even in the fraction of a second before excited mice start rubbing their faces, when the animals are relatively still, it can be difficult to identify the brain signals associated with heat and pressure perception that trigger whisker movement. So the researchers developed new tools and computational algorithms to differentiate the reaction of excited laboratory mice.
Wang says the new findings could shed light on a condition called thalamic pain syndrome, a chronic pain disorder that can develop in patients after a stroke that affects the thalamus in the brain.
