Hugging, holding hands, and caring give us a psychological boost that is known to be important for emotional well-being and healthy development.
But until now, it hasn’t been clear why we get pleasure from this type of contact.
Now researchers at Washington University School of Medicine in St. Louis have identified a neural circuitry and a neuropeptide – a chemical messenger that carries signals between nerve cells – that transmit the sensation known as “pleasant touch” from the skin to the brain.
They say the discovery of the neural circuitry and a neuropeptide in mice can help scientists better understand and treat disorders characterized by avoidance of touch and impaired social development in humans, including autism spectrum disorder.
Pleasant tactile sensations such as hugging give us a psychological boost that is known to be important for emotional well-being and healthy development.
Pleasant tactile sensation is very important in all mammals. Now researchers have identified a neural circuit that transmits this sensation from the skin to the brain
“Pleasant tactile sensation is very important in all mammals,” said Dr. Zhou-Feng Chen, director of the Center for the Study of Itch & Sensory Disorders at Washington University, who led the study.
‘One important way babies are fed is through touch. Holding the hand of a dying person is a very powerful and comforting force. Animals clean each other. People hug and shake hands. Massage therapy reduces pain and stress and can provide benefits to patients with psychiatric disorders.
‘In these experiments with mice, we identified a key neuropeptide and a hard-wired neural pathway dedicated to this sensation.’
Chen’s team found that when they raised mice without the neuropeptide, called procinecticin 2 (PROK2), they could not perceive pleasant tactile signals, but continued to react normally to itching and other stimuli.
“Now that we know which neuropeptide and receptor only transmit pleasant tactile sensations, it may be possible to enhance pleasant tactile signals without interfering with other circuits,” he said.
‘[This] it’s because the pivotal and pleasant touch stimulates several hormones in the brain that are essential for social interactions and mental health. ‘
Chen’s team found that mice designed to be PROK2-free avoided activities such as grooming and showed signs of stress not seen in normal mice.
The researchers also found that mice lacking a pleasant tactile sensation from birth had more severe stress responses and exhibited greater social avoidance behavior than mice whose pleasant tactile response was blocked in adulthood.
Chen said the finding underscores the importance of maternal touch in the development of offspring.
Holding the hand of a dying person is a “powerful and comforting force,” as researchers say
“Mothers love to lick their pups, and adult mice also frequently groom each other for good reasons, such as aiding emotional bonding, sleep and stress relief,” she said.
“But these rats avoid it. Even when their cage mates try to clean them, they drift away. They don’t even clean other mice. They are withdrawn and isolated. ‘
One of the study’s challenges was figuring out how to get mice to let themselves be touched and interpret how certain types of touch felt for mice, according to Chen.
“If an animal doesn’t know you, it usually turns away from any kind of touch because it can see it as a threat,” she said.
“Our difficult task was to design experiments that would help overcome animals’ instinctive avoidance of touch.”
To get the mice to cooperate – and to know if they felt a pleasant touch – the researchers kept the mice separate from cage mates for a while, after which the animals were more prone to being stroked with a soft, pet-like brush. who are stroked and groomed.
After several days of such brushing, the mice were then placed in a two-chamber environment. In one room the animals were brushed. There was no stimulus in the other room.
When given a choice, the mice went to the room where they would be brushed.
Mice engage in grooming behavior, experiencing a phenomenon that researchers call pleasant touch. The findings could ultimately help scientists better understand and treat disorders characterized by avoidance of touch and impaired social development.
Next, Chen’s team began working to identify the neuropeptides that were activated by a leisurely brushing.
They found that PROK2 in sensory neurons and in the neural circuit of the spinal cord that expresses its receptor (PROKR2) transmitted pleasant tactile signals to the brain.
In further experiments, they found that the neuropeptide they settled on was not involved in the transmission of other sensory signals, such as pruritus.
Chen, whose lab was the first to identify a similar, dedicated pathway for itching, said the pleasant tactile sensation is conveyed by an entirely different dedicated network.
“Just as we have itch-specific cells and peptides, we’ve now identified pleasant touch-specific neurons and a peptide to transmit those signals,” he said.
The study was published in the journal Science.
YOU MAY SOON FEEL PAIN IN THE METAVERSE
The idea of a bracelet that can mimic pain in the metaverse may sound like a concept from the latest Black Mirror series.
But thanks to a Japanese start-up, the creepy device has become a reality.
H2L, a Sony-backed company based in Tokyo, has developed a bracelet that uses electrical stimulation to deliver physical pain.
The armband, called UnlimitedHand, features muscle motion sensors that recognize hand gestures and position, allowing your avatar in the metaverse to accurately copy your movements.
It also uses electrical stimulation to manipulate the arm muscles, mimicking sensations.
‘Feeling the pain allows us to transform the world of the metaverse into a real one [world]with a greater sense of presence and immersion, “said Emi Tamaki, CEO and co-founder of H2L.
