Functional neuroimaging provides a powerful tool for understanding how the brain may be involved in the perception of pain. It has made it possible to identify areas of the brain that are involved in the perception of experimental pain but very few studies have evaluated the sites in the brain that are activated during clinical pain and the effects of analgesic drugs. The proposed study will use the surgical removal of an impacted third molar as a model of acute clinical pain to identify sites that are activated following the offset of local anesthesia and to examine the effects of the NSAID analgesic ketorolac on attenuating sites that are activated as pain is relieved. Scans will be performed under non-pain baseline conditions, and again immediately following surgery as the local anesthetic wears off, clinical pain occurs, and following administration of the NSAID ketorolac. Differences among subjects in the amount of pain reported and brain activation will be compared to subjects' prior ratings of experimental pain and the presence of any genetic polymorphisms that are related to pain perception, inflammation, known pain pathways, or psychological factors related to pain. The findings from this research may help to reveal how pain is appreciated in the central nervous system, pharmacologically modified by NSAID analgesics and differs among individuals due to genetic factors.