Touch of hand eases 'ouch' moments

Researchers at 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 the 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 studied the effects of self-touch in people who were made to feel pain using an experimental condition called the “thermal grill illusion (TGI)”. According to Haggard, TGI is one of the best-established laboratory methods for studying pain perception.

The scientists said that earlier studies of chronic pain had suggested the importance of body representation in the experience of pain.

For example, the phantom pain that is often felt following amputation of a limb appears to lessen with time as the brain converges on an updated representation of the body.