title: Hypnotically induced somatosensory alterations: Toward a neurophysiological understanding of hypnotic anaesthesia.
abstract: Whereas numerous studies have investigated hypnotic analgesia, few have investigated hypnotic anaesthesia. Using magnetoencephalography (MEG) we investigated and localized brain responses (event-related fields and oscillatory activity) during sensory processing under hypnotic anaesthesia. Nineteen right handed neurotypical individuals with moderate-to-high hypnotizability received 100 vibrotactile stimuli to right and left index fingers in a random sequence. Thereafter a hypnotic state was induced, in which anaesthetic suggestion was applied to the left hand only. Once anaesthetic suggestion was achieved, a second, identical, session of vibrotactile stimuli was commenced. We found greater brain activity in response to the stimuli delivered to the left (attenuated) hand before hypnotic anaesthesia, than under hypnotic anaesthesia, in both the beta and alpha bands. In the beta band, the reduction of activity under hypnotic anaesthesia was found around 214-413ms post-stimuli and was located mainly in the right insula. In the alpha band, it was found around 253-500ms post-stimuli and was located mainly in the left inferior frontal gyrus. In a second experiment, attention modulation per se was ruled out as the underlying cause of the effects found. These findings may suggest that the brain mechanism underlying hypnotic anaesthesia involves top-down somatosensory inhibition and, therefore, a reduction of somatosensory awareness. The result of this mechanism is a mental state in which individuals lose bodily sensation.
authors.affiliation: Gonda Brain Research Center, Bar Ilan University, Ramat-Gan, Israel; The Academic College of Society and the Arts, Netanya, Israel. Electronic address: maorwolf@gmail.com.
authors.forename: Maor
authors.initials: M
authors.lastname: Zeev-Wolf
authors.affiliation: Gonda Brain Research Center, Bar Ilan University, Ramat-Gan, Israel; Department of Psychology, Bar Ilan University, Ramat-Gan, Israel.
authors.forename: Abraham
authors.initials: A
authors.lastname: Goldstein
authors.affiliation: Hadassah Medical Center and Hebrew University, Jerusalem, Israel.
authors.forename: Omer
authors.initials: O
authors.lastname: Bonne
authors.affiliation: Hadassah Medical Center and Hebrew University, Jerusalem, Israel.
authors.forename: Eitan G
authors.initials: EG
authors.lastname: Abramowitz
mesh_terms: D000328:Adult; D000513:Alpha Rhythm; D000758:Anesthesia / Q000379:methods*; D001611:Beta Rhythm; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D006990:Hypnosis / Q000379:methods*; D015225:Magnetoencephalography; D008297:Male; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology*; D010812:Physical Stimulation; D011795:Surveys and Questionnaires
keywords: Hypnosis; Hypnotic Anaesthesia; Insula; Magnetoencephalography; Somatosensory