Journal Article

A spatiotemporal signature of cortical pain relief by tactile stimulation: An MEG study

Hagiwara, Koichi, Hayamizu, Mariko, Hoka, Sumio, Tobimatsu, Shozo, Ogata, Katsuya, Hironaga, Naruhito

2016

Overview

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. •We investigated cortical mechanism of tactile-induced pain relief using MEG.•Aδ inputs were modified by Aβ stimulation either at the spinal or cortical level.•Pain and tactile activities were segregated within the insular-opercular region.•Pain-related activity was suppressed in the posterior insula.•Cortical pain relief can occur in the posterior insula.

• Publisher: Elsevier Inc,Elsevier Limited
• Subject: Adult / Analgesia / Analgesics / Brain Mapping - methods / Cerebral Cortex - physiology / Cortex / Electrical stimuli / Experiments / Female / Forearm / Humans / Insular–opercular region / Intra-epidermal electrical stimulation / Localization / Magnetoencephalography / Magnetoencephalography - methods / Male / Mechanical tactile stimulation / Middle Aged / Operculum / Pain management / Pain Management - methods / Pain Measurement / Pain perception / Physical Stimulation - methods / Sensory integration / Signal Processing, Computer-Assisted / Spinal cord / Studies / Tactile stimuli / Tactile-induced analgesia / Touch - physiology / Vertebrae