| 摘要 |
Despite research progress identifying brain mechanisms mediating the experience of pain, our understanding of chronic pain lags behind experimentally-induced pain, largely because paradigms for studying the mechanisms of chronic pain have been limited. Here, we present a novel paradigm in which patients increase their own chronic pain experience by tensing the muscles surrounding their pain site, producing pain similar to that experienced during everyday muscle use. A broad sample of chronic pain patients report increased pain severity while tensing their pain site, and their pain remains elevated following tensing when the patients are no longer performing an overt task, mimicking sustained pain in their everyday experience. When patients perform this task during fMRI scanning, increased activation is observed throughout the 'pain matrix' including the thalamus and regions of insular, somatosensory, cingulate, prefrontal and orbitofrontal cortices. Following the termination of muscle tensing, pain remains elevated as reported using continuous quantitative pain ratings, and fMRI activation similarly remains elevated in anterior insular, cingulate, and somatosensory cortices. Activation in dorsal anterior cingulate cortex is linearly correlated with patients' pain ratings during the tensing period. Only the right anterior insula shows a correlation between activation and pain ratings during sustained pain. The activation pattern observed is similar when subjects repeat the task without providing continuous pain ratings. These results delineate brain regions mediating the perception of chronic pain, rather than acute experimental pain and provide a new approach to examining brain mechanisms of this disease. |
