Scientists scanned the brains of 15 health volunteers naive to meditation using arterial spin labeling magnetic resonance imaging (ASL MRI). During the scan, a heat device was placed on the right legs of subjects that warmed the area to 120 degrees Fahrenheit over 5 minutes. Most people experience this stimulus as painful.
The scans were conducted prior to meditation and after four 20 minute classes in a technique known as focused attention. In focused attention people pay attention to their breath while letting go of distracting thoughts or emotions.
Amazingly, after meditation training, pain intensity was reported to be 40% less on average, while pain unpleasantness was rated 57% lower. Every participant rated their pain lower after meditation from an 11% reduction up to a 93% reduction. Most opiate painkillers reduce pain by 25%.
The scientists reported that brain activity was reduced in the primary somatosensory cortex while increased in the anterior cingulate cortex, anterior insula, and orbiot-frontal cortex after meditation. These areas of the brain are involved in feeling the location and intensity of pain as well as creating the experience of the pain. It appears that meditation works on multiple areas of the brain responsible for multiple pathways that process the experience of pain.
Although the results of this study are limited by the small number of participants, the implications of this information is intriguing. Meditation produced dramatic pain-reducing effects after only 1 hour 20 minutes of instruction. The potential to reduce pain was greater than traditional pain medications.
You can read the abstract of this study at: http://www.jneurosci.org/content/31/14/5540.abstract