Supraspinal facilitation to repetitive painful stimulation: A laser evoked potential study.

To better characterize central modulation mechanisms involved in the processing of daily repetitive painful stimulation, laser evoked potentials were recorded at and away from the conditioning area in healthy participants. In addition, we aimed to evaluate a repetitive painful stimulation paradigm that could be conducted in a shorter time frame than previous studies. Collectively, continuous pain rating, warm and heat pain threshold results suggest that sensitivity to pain was reduced 24 hours after the shortened repeated painful stimulation. Laser evoked potentials revealed a significant increase in the contralateral arm to where the conditioning stimulus was applied. This finding was specific to noxious conditioning (i.e., not seen in the control brush experiment). These results provide neurophysiological evidence of pain facilitation resulting from prolonged exposure to painful heat, potentially arising in supraspinal structures.