The objectives of this project are (1) to assess psychophysical methods of experimental pain measurement, i.e., magnitude estimation, category scaling, and cross-modality matching. Pain will be experimentally induced by electrocutaneous, electric tooth pulp, and mechanical heat stimulation; (2) to assess clinical pain measures, such as pain questionnaires and sensory matching methods, in a dental setting; (3) to determine the validity of experimental pain models by comparison of experimental and clinical pain responses; and (4) to evaluate known pharmacological and non-pharmacological pain-control agents. The interactive computer-based staircase scaling method was used in three experiments. This method requires subjects to use a category scale to rate thermal stimuli applied to their volar forearm. Stimuli are associated with specific randomly presented staircases. Successive stimuli within each staircase are continuously adjusted to produce a preassigned level of verbal (e.g. mild, moderate, intense) responding. The first experiment expanded a number of staircases from three to six to cover assessment of non-painful warmth sensations and a broad range of pain intensities. It successfully tracks the time course of thermocutaneous sensitivity from just-detectable warmth sensation (39 deg C) to very painful sensations (51 deg C). The second experiment showed that both the magnitude of fentanyl analgesia and rate of analgesia onset were dose dependent. The most sensitive assessment was provided by intermediate stimulus temperatures. The third experiment identified patterns of temporal suppression at nearthreshold (45 deg C) stimulus temperatures. Subjects either showed a mild suppression of 0-1.5 deg C or a greater depression of 4-5 deg C.
