Pain travels through more than one brain pathway during processing, which could explain why some people who experience painful events may not process the feelings immediately. Until now, medical researchers have been unable to adequately explain this phenomenon.
University of Colorado Boulder (CU-Boulder) researchers discovered that cognitive self-regulation, a psychological technique to manage pain, works without altering the degree of nerve signals from a wound.
Medical researchers once believed that pain signals were processed in just a single area of the brain. In recent years, this idea has fallen out of favor, and this new study adds support to the modern hypothesis.
"We found that there are two different pathways in our brains that contribute to the pain experience," Choong-Wan Woo, a doctoral student in the Department of Psychology and Neuroscience at CU-Boulder, said.
Investigators examined brains of the subjects in the study using functional magnetic resonance imaging (fMRI) while applying pain stimulus in the form of a heated patch placed on arms of the participants. People receiving the feelings of pain were asked to experience the stimulus under three conditions - with a blank mind, while imagining the pad was damaging their skin, and picturing the feelings of heat as a welcome experience on a cold day. Researchers found that compared to a blank mind, subjects experienced the most pain when picturing their skin being damaged, and least when the feelings were thought of as welcome.
Nerve signals remained identical over the three scenarios, although activity in the second channel altered, based on the mental attitude of the subject being examined.
One of the two pathways identified in the study contributes to feelings of physical pain, activating areas of the brain traditionally associated with feelings of pain. The second pathway, unknown before this newest research, is connected to regions of the brain typically associated with emotions and motivation. Researchers believe this second pathway could help explain how feelings could alter the experience of pain.
"Previously people did not have this specific brain marker for pain. Incorporating that measure, and identifying a separate pathway that makes an independent contribution to pain, is a major innovation of this paper," Woo said.
This new finding could help health care professionals develop new treatments for severe or chronic pain. According to the American Academy of Pain Medicine, roughly 100 million American adults suffer from chronic pain, making it one of the most common health problems in the nation.
"Distinct Brain Systems Mediate the Effects of Nociceptive Input and Self-Regulation on Pain", a study of the effect of brain pathways on feelings of pain, was published in the journal Plos Biology.