title: Brain oscillations differentially encode noxious stimulus intensity and pain intensity.
abstract: Noxious stimuli induce physiological processes which commonly translate into pain. However, under certain conditions, pain intensity can substantially dissociate from stimulus intensity, e.g. during longer-lasting pain in chronic pain syndromes. How stimulus intensity and pain intensity are differentially represented in the human brain is, however, not yet fully understood. We therefore used electroencephalography (EEG) to investigate the cerebral representation of noxious stimulus intensity and pain intensity during 10min of painful heat stimulation in 39 healthy human participants. Time courses of objective stimulus intensity and subjective pain ratings indicated a dissociation of both measures. EEG data showed that stimulus intensity was encoded by decreases of neuronal oscillations at alpha and beta frequencies in sensorimotor areas. In contrast, pain intensity was encoded by gamma oscillations in the medial prefrontal cortex. Contrasting right versus left hand stimulation revealed that the encoding of stimulus intensity in contralateral sensorimotor areas depended on the stimulation side. In contrast, a conjunction analysis of right and left hand stimulation revealed that the encoding of pain in the medial prefrontal cortex was independent of the side of stimulation. Thus, the translation of noxious stimulus intensity into pain is associated with a change from a spatially specific representation of stimulus intensity by alpha and beta oscillations in sensorimotor areas to a spatially independent representation of pain by gamma oscillations in brain areas related to cognitive and affective-motivational processes. These findings extend the understanding of the brain mechanisms of nociception and pain and their dissociations during longer-lasting pain as a key symptom of chronic pain syndromes.
authors.affiliation: Department of Neurology and TUM-Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Moritz M
authors.initials: MM
authors.lastname: Nickel
authors.affiliation: Department of Neurology and TUM-Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Elisabeth S
authors.initials: ES
authors.lastname: May
authors.affiliation: Department of Neurology and TUM-Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Tiemann
authors.affiliation: Department of Neurology and TUM-Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Schmidt
authors.affiliation: Department of Neurology and TUM-Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Postorino
authors.affiliation: Department of Neurology and TUM-Neuroimaging Center, Technische Universität München, 81675 Munich, Germany.
authors.forename: Son
authors.initials: S
authors.lastname: Ta Dinh
authors.affiliation: Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
authors.forename: Joachim
authors.initials: J
authors.lastname: Gross
authors.affiliation: Department of Neurology and TUM-Neuroimaging Center, Technische Universität München, 81675 Munich, Germany. Electronic address: markus.ploner@tum.de.
authors.forename: Markus
authors.initials: M
authors.lastname: Ploner
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D000513:Alpha Rhythm; D001611:Beta Rhythm; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D004569:Electroencephalography; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D065818:Gamma Rhythm / Q000502:physiology; D064368:Healthy Volunteers; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010146:Pain / Q000503:physiopathology / Q000523:psychology*; D010812:Physical Stimulation; D017397:Prefrontal Cortex / Q000503:physiopathology; D066191:Sensorimotor Cortex / Q000503:physiopathology; D055815:Young Adult
keywords: Alpha; Beta; Gamma; Nociception; Oscillations; Pain; Tonic