Stefanie F Bunk1, Stefan Lautenbacher2, Jascha Rüsseler3, Karin Müller2, Jana Schultz2, Miriam Kunz1. 1. a Department of General Practice and Elderly Care Medicine , University Medical Center Groningen, University of Groningen , Groningen , The Netherlands. 2. b Department of Physiological Psychology , Otto-Friedrich University , Bamberg , Germany. 3. c Department of Experimental Psychology, Cognition and Emotion Unit , Otto-Friedrich-University Bamberg , Germany.
Abstract
BACKGROUND: Many researchers have tried to investigate pain by studying brain responses. One method used to investigate pain-related brain responses is continuous electroencephalography (EEG). The objective of the current study is to add on to our understanding of EEG responses during pain, by differentiation between EEG patterns indicative of (i) the noxious stimulus intensity and (ii) the subjective pain sensation. METHODS: EEG was recorded during the administration of tonic experimental pain, consisting of six minutes of contact heat applied to the leg via a thermode. Two stimuli above pain threshold, one at pain threshold and two non-painful stimuli were administered. Thirty-six healthy participants provided a subjective pain rating during thermal stimulation. Relative EEG power was calculated for the frequency bands alpha1, alpha2, beta1, beta2, delta, and theta. RESULTS: Whereas EEG activity could not be predicted by stimulus intensity (except in one frequency band), subjective pain sensation could significantly predict differences in EEG activity in several frequency bands. An increase in the subjective pain sensation was associated with a decrease in alpha2, beta1, beta2 as well as in theta activity across the midline electrodes. CONCLUSION: The subjective experience of pain seems to capture unique variance in EEG activity above and beyond what is captured by noxious stimulus intensity.
BACKGROUND: Many researchers have tried to investigate pain by studying brain responses. One method used to investigate pain-related brain responses is continuous electroencephalography (EEG). The objective of the current study is to add on to our understanding of EEG responses during pain, by differentiation between EEG patterns indicative of (i) the noxious stimulus intensity and (ii) the subjective pain sensation. METHODS: EEG was recorded during the administration of tonic experimental pain, consisting of six minutes of contact heat applied to the leg via a thermode. Two stimuli above pain threshold, one at pain threshold and two non-painful stimuli were administered. Thirty-six healthy participants provided a subjective pain rating during thermal stimulation. Relative EEG power was calculated for the frequency bands alpha1, alpha2, beta1, beta2, delta, and theta. RESULTS: Whereas EEG activity could not be predicted by stimulus intensity (except in one frequency band), subjective pain sensation could significantly predict differences in EEG activity in several frequency bands. An increase in the subjective pain sensation was associated with a decrease in alpha2, beta1, beta2 as well as in theta activity across the midline electrodes. CONCLUSION: The subjective experience of pain seems to capture unique variance in EEG activity above and beyond what is captured by noxious stimulus intensity.