Research about skin sensation gave insights into pain

Håkan Olausson’s breakthrough research has partially upset the textbook description of the nervous system. His research group recently discovered a previously unknown component of the human pain-signalling system.

Håkan Olausson is doing research on pain sensation. Photo credit Charlotte Perhammar Håkan Olausson wasn’t at all sure that he wanted to be a doctor. In upper secondary school, maths and physics were his favourite subjects. He was so attracted by the idea of becoming a graduate engineer that he applied for entry to the engineering programme in technical physics several times while studying medicine. In fact, he was accepted.
But instead he kept at his studies of medicine in Gothenburg, which eventually led him to research. He met Professor Ulf Norrsell at a lecture.Håkan Olausson.Håkan Olausson. Photo credit Thor Balkhed

“He impressed me a great deal. I asked if I could start doctoral studies under him, but I didn’t have a clue what he was working on. When I found out that he was working with skin sensation I thought it sounded a bit weird – surely that wasn’t a major problem to solve for humanity? But I became fascinated by the topic, and I’ve worked on it ever since”, says Håkan Olausson, professor in the Department of Biomedical and Clinical Sciences, where he works in the Center for Social and Affective Neuroscience (CSAN).

So far in his research career, he has made two major contributions in understanding the human nervous system. Somewhat simplified, there are two types of nerve: nerve signals for skin sensation and skin touch are conducted in fast nerves, while pain signals are conducted in nerves that are significantly slower.

The first discovery in which Håkan Olausson participated is that humans have a special type of nerve, which according to previous beliefs didn’t exist. It transmits the pleasant feeling of slow skin touch.

The next discovery from his research group came in 2019 when they discovered that humans have pain-transmission fibres, which conduct the nerve signals just as rapidly as the nerves for skin touch.

“It has long been known that this type of nerve is present in various mammals, but it was generally thought to be absent in humans.”

Håkan Olausson has worked for many years with a special technique to measure nerve signals. He uses this method, neurography, in his medical practice as consultant in clinical neurophysiology, investigating nerve damage in patients. When conducting research, the group uses an even more sensitive variant, microneurography, that makes it possible to measure electrical impulses in an individual nerve cell.

When the LiU scientists measured the conduction speed from all the nerves that they found in experimental subjects, they found a group of nerves that had not been previously described. These formed an ultrarapid pain system.a thin electrode is inserted into the armThe researchers used a technique that allowed them to detect the signals in the nerve fibres from a single nerve cell. Photo credit Charlotte Perhammar

After this discovery, the LiU researchers have started to investigate how the ultrarapid pain cells function in normal conditions. Do they play a role in the reflex action of jerking away your hand when you cut your thumb? Do they react only to mechanical stimuli, such as pinching and needlesticks, or also to heat and cold? In particular, the researchers want to determine whether these nerves are involved in chronic pain.

“In the future, we want look at whether the function of these nerve cells changes in a medical condition in which light skin touch causes pain. Are they involved, and if so how? This is a common condition in chronic pain and it’s very difficult to treat”, says Saad Nagi, principal research engineer in the research group.

For most of us, the sense of touch is taken for granted, and we hardly think about how it works. It might be natural to assume that science has found out all there is to know about our nervous system. But 30 years of research into skin sensation and pain has taught Håkan Olausson the opposite.

“It feels as if we are barely scraping the surface in our basic understanding of how sensation and the nervous system work. We don’t know how the nerve signals are processed at the first connection between two nerve cells, or how they are interpreted in the brain.”Håkan Olausson.Håkan Olausson, professor in clinical neurophysiology. Photo credit Charlotte Perhammar

There are many other questions that he would like the answers to. What aspect of the nerve signalling process is it that gives rise to an experience? And is it possible to protect nerves, such that the patients he sees in the clinic can avoid nerve damage? Maybe research into the ultrarapid pain system can give some pieces of the puzzle.

“Chronic pain is an enormous problem. It would be fantastic if our discovery can give better pain diagnosis, or in the long run help other researchers to develop better pain relief”, says Håkan Olausson.

This article has also been published in LiU Magazine 2/20.

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