Ultra-slow mechanical stimulation of olfactory epithelium modulates consciousness by slowing cerebral rhythms in humans.
A Piarulli, A Zaccaro, M Laurino, D Menicucci, A De Vito, L Bruschini, S Berrettini, M Bergamasco, S Laureys, A Gemignani
Scientific Reports April 26, 2018 DOI: 10.1038/s41598-018-24924-9 (opens in new tab) via PubMed
Summary
AI-generated from the abstractPeriodic odorless air puffs delivered to the olfactory epithelium at 0.05 Hz (8 seconds on, 12 seconds off) in 12 healthy subjects enhanced delta-theta EEG activity across the whole cortex, especially in limbic system and default mode network structures, reversed the direction of information flow from a wake-like posterior-to-anterior pattern to a NREM sleep-like anterior-to-posterior pattern, and produced self-reported altered states of consciousness. The findings suggest a neurophysiological basis for how respiration-based meditative practices may induce altered states of consciousness.
Study at a glance
| Characteristics | Experimental study Peer reviewed |
|---|---|
| Sample size | 12 |
| Population | Healthy subjects |
| Key finding | Periodic odorless air stimulation of the olfactory epithelium enhanced delta-theta EEG activity, reversed information flow directionality, and induced altered states of consciousness. |
Abstract
The coupling between respiration and neural activity within olfactory areas and hippocampus has recently been unambiguously demonstrated, its neurophysiological basis sustained by the well-assessed mechanical sensitivity of the olfactory epithelium. We herein hypothesize that this coupling reverberates to the whole brain, possibly modulating the subject's behavior and state of consciousness. The olfactory epithelium of 12 healthy subjects was stimulated with periodical odorless air-delivery (frequency 0.05 Hz, 8 s on, 12 off). Cortical electrical activity (High Density-EEG) and perceived state of consciousness have been studied. The stimulation induced i) an enhancement of delta-theta EEG activity over the whole cortex mainly involving the Limbic System and Default Mode Network structures, ii) a reversal of the overall information flow directionality from wake-like postero-anterior to NREM sleep-like antero-posterior, iii) the perception of having experienced an Altered State of Consciousness. These findings could shed further light via a neurophenomenological approach on the links between respiration, cerebral activity and subjective experience, suggesting a plausible neurophysiological basis for interpreting altered states of consciousness induced by respiration-based meditative practices.