Brain Network Reconfiguration and Perceptual Decoupling During an Absorptive State of Consciousness.
Michael J Hove, Johannes Stelzer, Till Nierhaus, Sabrina D Thiel, Christopher Gundlach, Daniel S Margulies, Koene R A Van Dijk, Robert Turner, Peter E Keller, Björn Merker
Cerebral cortex (New York, N.Y. : 1991) July 1, 2016 Peer reviewed DOI: 10.1093/cercor/bhv137 via PubMed
Summary
Trance, an absorptive state with narrowed awareness, was studied in 15 experienced shamanic practitioners using fMRI while they listened to rhythmic drumming. During trance, three brain regions—posterior cingulate cortex, dorsal anterior cingulate cortex, and left insula/operculum—showed stronger hub properties (higher eigenvector centrality). The posterior cingulate cortex, a default network hub, coactivated with control-network regions, suggesting an amplified internal train of thought. Auditory pathway seeds became less connected, indicating perceptual decoupling from the repetitive drumming. This network reconfiguration may support extended internal reflection and insight.
Study at a glance
| Design | observational cohort |
|---|---|
| Sample size | 15 |
| Population | experienced shamanic practitioners |
| Key finding | Trance was associated with higher eigenvector centrality in the posterior cingulate cortex, dorsal anterior cingulate cortex, and left insula/operculum, along with coactivation of default and control networks and decoupled sensory processing. |
Abstract
Trance is an absorptive state of consciousness characterized by narrowed awareness of external surroundings and has long been used-for example, by shamans-to gain insight. Shamans across cultures often induce trance by listening to rhythmic drumming. Using functional magnetic resonance imaging (fMRI), we examined the brain-network configuration associated with trance. Experienced shamanic practitioners (n = 15) listened to rhythmic drumming, and either entered a trance state or remained in a nontrance state during 8-min scans. We analyzed changes in network connectivity. Trance was associated with higher eigenvector centrality (i.e., stronger hubs) in 3 regions: posterior cingulate cortex (PCC), dorsal anterior cingulate cortex (dACC), and left insula/operculum. Seed-based analysis revealed increased coactivation of the PCC (a default network hub involved in internally oriented cognitive states) with the dACC and insula (control-network regions involved in maintaining relevant neural streams). This coactivation suggests that an internally oriented neural stream was amplified by the modulatory control network. Additionally, during trance, seeds within the auditory pathway were less connected, possibly indicating perceptual decoupling and suppression of the repetitive auditory stimuli. In sum, trance involved coactive default and control networks, and decoupled sensory processing. This network reconfiguration may promote an extended internal train of thought wherein integration and insight can occur.