title: The human brain response to dental pain relief.
abstract: Local anesthesia has made dental treatment more comfortable since 1884, but little is known about associated brain mechanisms. Functional magnetic resonance imaging is a modern neuroimaging tool widely used for investigating human brain activity related to sensory perceptions, including pain. Most brain regions that respond to experimental noxious stimuli have recently been found to react not only to nociception alone, but also to visual, auditory, and other stimuli. Thus, presumed functional attributions have come under scrutiny regarding selective pain processing in the brain. Evidently, innovative approaches are warranted to identify cerebral regions that are nociceptive specific. In this study, we aimed at circumventing known methodological confounders by applying a novel paradigm in 14 volunteers: rather than varying the intensity and thus the salience of painful stimuli, we applied repetitive noxious dental stimuli at constant intensity to the left mandibular canine. During the functional magnetic resonance imaging paradigm, we suppressed the nociceptive barrage by a mental nerve block. Brain activity before and after injection of 4% articaine was compared intraindividually on a group level. Dental pain extinction was observed to correspond to activity reduction in a discrete region of the left posterior insular cortex. These results confirm previous reports demonstrating that direct electrical stimulation of this brain region-but not of others-evokes bodily pain sensations. Hence, our investigation adds further evidence to the notion that the posterior insula plays a unique role in nociceptive processing.
authors.affiliation: Center of Dental Medicine, University of Zurich, Zurich, Switzerland Balgrist University Hospital, Zurich, Switzerland Michael.meier@uzh.ch.
authors.forename: M L
authors.initials: ML
authors.lastname: Meier
authors.affiliation: Center of Dental Medicine, University of Zurich, Zurich, Switzerland Department of Psychiatry (UPK), University of Basel, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Widmayer
authors.affiliation: Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Abazi
authors.affiliation: Center of Dental Medicine, University of Zurich, Zurich, Switzerland Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Brügger
authors.affiliation: Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Lukic
authors.affiliation: Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Lüchinger
authors.affiliation: Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: D A
authors.initials: DA
authors.lastname: Ettlin
mesh_terms: D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage; D001921:Brain / Q000503:physiopathology*; D002355:Carticaine / Q000008:administration & dosage; D002531:Cerebellum / Q000503:physiopathology; D002540:Cerebral Cortex / Q000503:physiopathology; D002680:Chin / Q000294:innervation; D003481:Cuspid / Q000187:drug effects / Q000294:innervation; D004558:Electric Stimulation; D006179:Gyrus Cinguli / Q000503:physiopathology; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009407:Nerve Block / Q000379:methods; D009434:Neural Pathways / Q000503:physiopathology; D059225:Nociception / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000503:physiopathology; D010296:Parietal Lobe / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000503:physiopathology; D013702:Temporal Lobe / Q000503:physiopathology; D013788:Thalamus / Q000503:physiopathology; D014098:Toothache / Q000188:drug therapy* / Q000503:physiopathology; D014793:Visual Cortex / Q000503:physiopathology; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local; D002355:Carticaine
keywords: analgesia; anesthesia; insular cortex; magnetic resonance imaging; neuroscience/neurobiology; nociception