Scan illustrates activity in the primary somatosensory cortex. This area is highly active during pain and rest. But activity is far less during meditation and pain. Credit: Fadel Zeidan

New Delhi, April 5: Scientists have used magnetic resonance imaging scans of the brain to unravel the mechanisms through which a meditation technique with roots in ancient India may reduce the intensity and unpleasantness of pain.

While earlier studies have shown that meditation may reduce pain, the new research by US scientists is the first to probe the mechanisms that alter the sensation of pain after less than 90 minutes of meditation training.

Neuroscientist Fadel Zeidan and his colleagues in the US have found that a meditation technique related to traditions called Samatha and Vipassana can lead to a 40 per cent reduction in pain intensity and a 57 per cent reduction in pain unpleasantness.

Their findings, scheduled to appear in The Journal of Neuroscience tomorrow, provide unique insights into how meditation changes the experience of pain.

“Meditation reduces pain via multiple mechanisms,” said Zeidan, a researcher at the department of neurobiology at the Wake Forest University School of Medicine in the US. “This functional MRI study takes us closer to understanding these mechanisms.”

In their experiments, 15 health volunteers who had never meditated before were trained for 20 minutes a day, for four days. The researchers then exposed them to a painful high temperature stimulus on the skin and observed their MRI scans.

Every participant reported a reduction in pain, the highest a 93 per cent drop. The scans revealed that meditation significantly reduced brain activity in a region called the primary somatosensory cortex, an area involved in creating the feeling and intensity of pain.

When the volunteers mediated, the activity dropped to nearly undetectable levels. “This suggests that meditation reduces the information that goes through this area during the pain,” Zeidan told The Telegraph. “The pain signal appears softer.”

The meditation requires a person to relax, focus attention on the breath, acknowledge any distracting thoughts or emotions, but let them go gently, and turn the attention back on the breath. Any distracting thoughts are acknowledged without any emotions, Ziedan said.

“This study provides a new understanding of what brain areas are affected by a form of meditation that is easy to learn and easy to practice,” said Mahendra Sharma, a professor at the National Institute of Mental Health and Neuroscience, Bangalore.

“The primary somatosensory cortex is responsible for the subjective experience of pain,” said Sharma, who was not associated with the US study but has been investigating the use of meditation techniques in mental health for nearly 20 years.

Most earlier studies on meditation therapy involved extensive training sessions lasting up to eight weeks or longer, said Sharma, who had published a paper on meditation to combat tension headaches in 1990.

The technique applied by Zeidan and his colleagues is also called mindfulness meditation uses methods similar to those of Samatha or Vipassana — the traditional techniques that emerged more than 2,000 years ago in India.

Their study also showed that meditation increased brain activity in the anterior cingulate cortex, the anterior insula and the orbito-frontal cortex — areas that help the brain build the experience of pain from nerve signals.

“The more these areas were activated, the more the pain was reduced,” said Robert Coghill, associate professor of neurobiology at Wake Forest.

“One reason that meditation may have been so effective in blocking pain was that it did not work at just one place in the brain, but instead reduced pain at multiple levels of processing,” Coghill said in a statement issued through the university.