A New Research Report From College Of London

"Ever wondered why people hold on tightly the body part when injured? It’s because self-touch offers great relief for acute pain, scientists claim"
Researchers at the University College London found that the relief comes from a change in the brain’s representation of the rest of the body. “Pain is quite an important, but also complicated, experience and can be caused in many different ways,” said Patrick Haggard, the lead author of study, published online in journal Current Biology.

• “We show that levels of acute pain depend not just on the signals sent to the brain, but also on how the brain integrates these signals into a coherent representation of the body as a whole.” For the research, Haggard and his colleague Marjolein Kammers, also of University College London, studied the effects of self-touch in people who were made to feel pain using an experimental condition called the “thermal grill illusion (TGI)”.

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According to Haggard, TGI is one of the best-established laboratory methods for studying pain perception. “In our version, the index and ring fingers are placed in warm water and the middle finger in cold water. This generates a paradoxical feeling that the middle finger is painfully hot,” Haggard explained.

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• It was found that when TGI was induced in an individual’s two hands and then the three fingers of one hand were touched to the same fingers on the other hand immediately afterwards, the painful heat experienced by the middle finger dropped by 64 per cent compared to a condition without self-touch.

• That relief didn’t come when only one hand was placed under TGI conditions. Partial self-touch in which only one or two fingers were pressed against each other didn’t work either. Nor did it work to press the affected hand against an experimenter’s hand that had also been warmed and cooled in the same way.