Plasticity in brain processing and modulation of pain.

Brain processing of pain in humans is based on multiple ascending pathways and brain regions that are involved in several pain components, such as sensory, immediate affective, and secondary affective dimensions. These dimensions are processed both serially and in parallel. They include spinal ascending pathways that directly target limbic and brainstem structures involved in pain-related emotions as well as a pathway proceeding from the somatosensory cortices to limbic cortical areas. Superimposed on this neural organization is the capacity to process the dimensions of pain in multiple ways, as in patients who lack one cerebral hemisphere but can nevertheless locate and rate pain intensity and pain unpleasantness on both sides of the body. The dimensions of pain also can be psychologically modulated in multiple ways and these changes are accompanied by corresponding changes in relevant brain structures. Finally, understanding psychological modulation of pain and pain-related brain activity is optimized by a scientific framework that integrates principles of contemporary physics, neuroscience, and human experiential science.