Reducing Pain Just By Crossing Your Fingers?

Well, not exactly. But new research finds that how you feel pain is affected by where sources of pain are in relation to each other, and so crossing your fingers can change what you feel on a single finger.

The findings could help scientists better understand our reactions to pain on a biological level, and possibly lead to treatments for patients that suffer from chronic pain.

To shed some light on the subject, researchers used a variation on an established pain experiment known as the "thermal grill illusion." In this experiment, a pattern of warm-cold-warm temperatures is applied to the index, middle and ring finger, respectively. This causes a paradoxical, sometimes painful, sensation of burning heat on the middle finger - even though this finger is actually presented with a cold stimulus.

"The thermal grill is a useful component in our scientific understanding of pain," study co-author Angela Marotta, from the UCL Institute of Cognitive Neuroscience, said in a press release. "It uses a precisely-controlled stimulus to activate the brain's pain systems. This can certainly feel painful, but doesn't actually involve any tissue damage."

This refers to the paradox of this experiment, where the middle finger feels a burning sensation despite the fact that cold water, not warm, is being poured over it. That's because of the three-way interaction between the nerve pathways that tell the brain about warmth, cold and pain.

"Cold normally inhibits pain, so inhibiting the input from the cold stimulus produces an increase in pain signals," explained co-lead author Dr. Elisa Ferrè. "It's like two minuses making a plus."

However, when the middle finger was crossed over the index finger, the burning pain was reduced.

Conversely, if the index finger was cooled and the middle and ring fingers were warmed, the burning heat sensation was now increased when the middle finger was crossed over the index finger.

"Our results showed that a simple spatial pattern determined the burning heat sensation," said Dr. Ferrè.

"Interactions like these may contribute to the astonishing variability of pain," added senior author Professor Patrick Haggard. "Many people suffer from chronic pain, and the level of pain experienced can be higher than would be expected from actual tissue damage. Our research is basic laboratory science, but it raises the interesting possibility that pain levels could be manipulated by applying additional stimuli, and by moving one part of the body relative to others. Changing the spatial pattern of interacting inputs could have an effect on the brain pathways that underlie pain perception."

The results are described in further detail in the journal Current Biology.

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