Neural Correlates of Non-ordinary States of Consciousness in Pranayama Practitioners: The Role of Slow Nasal Breathing

Author: Andrea Zaccaro1,2, Andrea Piarulli1,3, Lorenza Melosini4, Danilo Menicucci1, Angelo Gemignani1,5
1 Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy.
2 Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy.
3 Giga Consciousness, Coma Science Group, University of Liège, Liège, Belgium.
4 Pneumology Branch, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy.
5 Clinical Psychology Branch, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy.
Conference/Journal: Front Syst Neurosci
Date published: 2022 Mar 21
Other: Volume ID: 16 , Pages: 803904 , Special Notes: doi: 10.3389/fnsys.2022.803904. , Word Count: 286

The modulatory effect of nasal respiration on integrative brain functions and hence consciousness has recently been unambiguously demonstrated. This effect is sustained by the olfactory epithelium mechanical sensitivity complemented by the existence of massive projections between the olfactory bulb and the prefrontal cortex. However, studies on slow nasal breathing (SNB) in the context of contemplative practices have sustained the fundamental role of respiratory vagal stimulation, with little attention to the contribution of the olfactory epithelium mechanical stimulation. This study aims at disentangling the effects of olfactory epithelium stimulation (proper of nasal breathing) from those related to respiratory vagal stimulation (common to slow nasal and mouth breathing). We investigated the psychophysiological (cardio-respiratory and electroencephalographic parameters) and phenomenological (perceived state of consciousness) aftereffects of SNB (epithelium mechanical - 2.5 breaths/min) in 12 experienced meditators. We compared the nasal breathing aftereffects with those observed after a session of mouth breathing at the same respiratory rate and with those related to a resting state condition. SNB induced (1) slowing of electroencephalography (EEG) activities (delta-theta bands) in prefrontal regions, (2) a widespread increase of theta and high-beta connectivity complemented by an increase of phase-amplitude coupling between the two bands in prefrontal and posterior regions belonging to the Default Mode Network, (3) an increase of high-beta networks small-worldness. (4) a higher perception of being in a non-ordinary state of consciousness. The emerging scenario strongly suggests that the effects of SNB, beyond the relative contribution of vagal stimulation, are mainly ascribable to olfactory epithelium stimulation. In conclusion, slow Pranayama breathing modulates brain activity and hence subjective experience up to the point of inducing a non-ordinary state of consciousness.

Keywords: EEG; altered consciousness; cortical activity modulation; olfactory epithelium; respiration; slow nasal breathing; small worldness.

PMID: 35387390 PMCID: PMC8977447 DOI: 10.3389/fnsys.2022.803904