A Northwestern University researcher has linked chronic pain to old memory traces. Essentially the emotional and learning of the pain becomes stuck in the prefrontal cortex of the brain. That is the part of the brain that experiences the emotional suffering of pain.
D-Cycolserine was used in animal studies to significantly reduce both pain and sensitivity from the injured site. The study was funded by the National Institutes of Health and will be published in the Journal of Pain later this year.