Why touching the skin relieves pain

April 15th, 2009 - 1:05 pm ICT by ANI  

Washington, April 15 (ANI): Scientists at the Sahlgrenska Academy have found out why touching the skin relieves pain.

The researchers have revealed that the skin has specialised nerve fibres called called CT nerves (C-tactile), which travel directly to the areas in the brain that are important in the emergence of feelings.

“Basically, the signals that tell the brain that we are being stroked on the skin have their own direct route to the brain, and are not blocked even if the brain is receiving pain impulses from the same area. In fact it’s more the opposite, that the stroking impulses are able to deaden the pain impulses,” Nature magazine quoted Line Loken, postgraduate student in neurophysiology at the Sahlgrenska Academy, as saying.

The researchers used a technique called microneurography to examine a group of healthy subjects.

“By inserting a thin electrode into a nerve in the forearm we can listen in on the nerve and pick up signals from one of the thousands of nerve fibres that make up a nerve,” explains Associate Professor Hakan Olausson, who is leading the research group behind the discovery, together with Johan Wessberg.

According to the research team, each individual nerve fibre was responsible for touch signals from roughly a square centimetre of skin.

During the study, the researchers used a specially-designed robot that brushed over the exact area of skin for which a particular nerve fibre is responsible.

They also asked the participants to rate how pleasant or unpleasant they found the brushing.

“As the nerve signals that were sent in the CT nerves became more frequent, the subjects reported the experience as being increasingly pleasant. Of the skin nerves that we studied, it was only the CT nerves that had this strong link between the frequency of the signals and how pleasant it felt,” says researcher Johan Wessberg.

The study has been published in the journal Nature Neuroscience. (ANI)

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