If your hand hurts, simply cross your arms; it will confuse the brain and reduce your pain intensity, according to scientists at University College London.
Researchers believe this happens because of conflicting information between two of the brain’s maps: the one for your body and the one for external space.
Since the left hand typically performs actions on the left side of space (and the right hand performs on the right side), these two maps work together to create powerful impulses in response to stimuli. When the arms are crossed, however, the two maps are mismatched and information processing becomes weaker — resulting in less pain.
“Perhaps when we get hurt, we should not only ‘rub it better’ but also cross our arms,” said lead author Giandomenico Iannetti of the UCL department of Physiology, Pharmacology and Neuroscience.
Using a laser, scientists produced a four millisecond pin prick of “pure pain” (pain without touch) on the hands of a small group of eight volunteers. It was then repeated with their arms crossed. The partipants’ brain responses to the pain were measured through electroencephalography (EEG); the volunteers also gave a rating on how much pain they felt during each circumstance.
The results from both the EEG and the participants’ reports revealed that the perception of pain was weaker when the arms were crossed.
“In everyday life you mostly use your left hand to touch things on the left side of the world, and your right hand for the right side of the world — for example when picking up a glass of water on your right side you generally use your right hand,” said Iannetti.
“This means that the areas of the brain that contain the map of the right body and the map of right external space are usually activated together, leading to highly effective processing of sensory stimuli. When you cross your arms these maps are not activated together anymore, leading to less effective brain processing of sensory stimuli, including pain, being perceived as weaker.”
According to the scientists, this new research could lead to novel clinical therapies to reduce pain that exploit the brain’s way of representing the body.
The study is published in the journal PAIN.
Source: University College London