title: A spatiotemporal signature of cortical pain relief by tactile stimulation: An MEG study.
abstract: Recently, the cortical mechanisms of tactile-induced analgesia have been investigated; however, spatiotemporal characteristics have not been fully elucidated. The insular-opercular region integrates multiple sensory inputs, and nociceptive modulation by other sensory inputs occurs in this area. In this study, we focused on the insular-opercular region to characterize the spatiotemporal signature of tactile-induced analgesia using magnetoencephalography in 11 healthy subjects. Aδ (intra-epidermal electrical stimulation) inputs were modified by Aβ (mechanical tactile stimulation) selective stimulation, either independently or concurrently, to the right forearm. The optimal inter-stimulus interval (ISI) for cortical level modulation was determined after comparing the 40-, 60-, and 80-ms ISI conditions, and the calculated cortical arrival time difference between Aδ and Aβ inputs. Subsequently, we adopted a 60-ms ISI for cortical modulation and a 0-ms ISI for spinal level modulation. Source localization using minimum norm estimates demonstrated that pain-related activity was located in the posterior insula, whereas tactile-related activity was estimated in the parietal operculum. We also found significant inhibition of pain-related activity in the posterior insula due to cortical modulation. In contrast, spinal modulation was observed both in the posterior insula and parietal operculum. Subjective pain, as evaluated by the visual analog scale, also showed significant reduction in both conditions. Therefore, our results demonstrated that the multisensory integration within the posterior insula plays a key role in tactile-induced analgesia.
authors: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: hayamizu@med.kyushu-u.ac.jp.
authors: Mariko
authors: M
authors: Hayamizu
authors: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Koichi
authors: K
authors: Hagiwara
authors: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Naruhito
authors: N
authors: Hironaga
authors: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Katsuya
authors: K
authors: Ogata
authors: Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Sumio
authors: S
authors: Hoka
authors: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Shozo
authors: S
authors: Tobimatsu
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D059408:Pain Management / Q000379:methods*; D010147:Pain Measurement; D010812:Physical Stimulation / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D014110:Touch / Q000502:physiology
keywords: Insular–opercular region; Intra-epidermal electrical stimulation; Magnetoencephalography; Mechanical tactile stimulation; Tactile-induced analgesia