title: Prefrontal Gamma Oscillations Encode Tonic Pain in Humans.
abstract: Under physiological conditions, momentary pain serves vital protective functions. Ongoing pain in chronic pain states, on the other hand, is a pathological condition that causes widespread suffering and whose treatment remains unsatisfactory. The brain mechanisms of ongoing pain are largely unknown. In this study, we applied tonic painful heat stimuli of varying degree to healthy human subjects, obtained continuous pain ratings, and recorded electroencephalograms to relate ongoing pain to brain activity. Our results reveal that the subjective perception of tonic pain is selectively encoded by gamma oscillations in the medial prefrontal cortex. We further observed that the encoding of subjective pain intensity experienced by the participants differs fundamentally from that of objective stimulus intensity and from that of brief pain stimuli. These observations point to a role for gamma oscillations in the medial prefrontal cortex in ongoing, tonic pain and thereby extend current concepts of the brain mechanisms of pain to the clinically relevant state of ongoing pain. Furthermore, our approach might help to identify a brain marker of ongoing pain, which may prove useful for the diagnosis and therapy of chronic pain.
authors.affiliation: Department of Neurology, Technische Universität München, 81675 Munich, Germany TUM - Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Enrico
authors.initials: E
authors.lastname: Schulz
authors.affiliation: Department of Neurology, Technische Universität München, 81675 Munich, Germany TUM - Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Elisabeth S
authors.initials: ES
authors.lastname: May
authors.affiliation: Department of Neurology, Technische Universität München, 81675 Munich, Germany TUM - Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Postorino
authors.affiliation: Department of Neurology, Technische Universität München, 81675 Munich, Germany TUM - Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Tiemann
authors.affiliation: Department of Neurology, Technische Universität München, 81675 Munich, Germany TUM - Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Moritz M
authors.initials: MM
authors.lastname: Nickel
authors.affiliation: Department of Theoretical Methods, Institute of Measurement Science, Slovak Academy of Sciences, 84219 Bratislava, Slovak Republic.
authors.forename: Viktor
authors.initials: V
authors.lastname: Witkovsky
authors.affiliation: Department of Neurology, Technische Universität München, 81675 Munich, Germany TUM - Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Schmidt
authors.affiliation: Centre for Cognitive Neuroimaging, Department of Psychology, University of Glasgow, Glasgow G12 8QB, UK.
authors.forename: Joachim
authors.initials: J
authors.lastname: Gross
authors.affiliation: Department of Neurology, Technische Universität München, 81675 Munich, Germany TUM - Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Ploner
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004569:Electroencephalography; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D008297:Male; D010146:Pain / Q000473:pathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D017397:Prefrontal Cortex / Q000503:physiopathology*; D011601:Psychophysics; D013997:Time Factors; D055815:Young Adult
keywords: electroencephalography; gamma oscillations; ongoing pain; pain perception; prefrontal cortex