The study, published in the medical journal Pain and led by researchers Joshua Grant and Pierre Rainville, furthered their previous study (2009) on the connection between sensitivity to pain and meditation. The earlier study had found that people who practice meditation are less sensitive to pain: the lowering of pain sensitivity correlated with the slowing of the respiratory rate and a greater meditation experience. However the researchers aimed to figure out why.
For the new study, Grant and Rainville exposed 13 Zen masters and 13 comparable non-practitioners to equal degrees of painful heat while measuring their brain activity in a functional magnetic resonance imaging (fMRI) scanner. The meditators reported feeling less pain than the control group. In fact, the meditating group reported feelings of pain at levels below what their neurological output from the fMRI indicated. In other words, their brains were receiving pain signals, but they weren't translating them into actual feelings of pain.
Researchers also found that compared to people who don’t meditate, meditators have thicker gray matter and central brain regions, specifically in an area know to influence perceptions of pain (the anterior cingulate). The neuroplastic differences found in the brains of meditators were the real cause of their lower sensitivity to pain.