Investigating the Neurophenomenological Dynamics of Breathwork and DMT

Altered states of consciousness (ASCs) that produce subjectively rich states, such as those induced by psychedelics, have recently been praised as useful tools within the neuroscience of consciousness, due to their radical and reversible impacts on both brain dynamics and subjective experience. However, much of the previous research has neglected measuring the dynamic subjective effects of these ASCs, preventing a refined understanding of how experience dynamics relate to neural dynamics. The work in this thesis attempts to address this gap by utilising Temporal Experience Tracing (TET), a retrospective methodology that preserves the temporal dynamics of subjective experience in a variety of distinct dimensions. Within Chapter 2, TET in combination with electroencephalography (EEG) was applied to study breathwork, a relatively understudied ASC that can induce subjective experience states adjacent to classic psychedelics through the voluntary modulation of the breath. 301 breathwork sessions were included in this analysis, representing one of the largest neurophenomenological datasets on ASCs to date. It was found that breathwork can indeed induce subjective experiences with overlapping qualities to classic psychedelics, and that these subjective experiences were related to changes in neural Lempel-Ziv complexity, a highly cited neural signature of the psychedelic state. Within Chapter 3, a similar methodological approach was applied to a dose-dependent naturalistic study on N,N-Dimethyltryptamine (DMT), a powerful and short-acting psychedelic. Phenomenological analyses revealed that the temporal dynamics of experience differed in a dose-dependent manner. Further, a variety of EEG features were computed and associated with the TET dimensions during the DMT dosing sessions. Oscillatory alpha power and permutation entropy markers were most strongly associated with subjective experiences, corroborating previous studies investigating the neural correlates of the DMT-state. However, contrary to previous evidence within psychedelic neuroscience, Lempel-Ziv complexity yielded the weakest experiential associations. Finally, in Chapter 4, both datasets were jointly analysed within a neurophenomenological approach. Phenomenological clustering on both datasets separately revealed two clusters: psychedelic(-like) clusters and opposing "off-task" clusters. These two clusters were contrasted using univariate and multivariate EEG analyses. Information theory metrics were most consistently associated with phenomenological clusters across datasets, with permutation entropy markers as the most consistent. Cross-decoding from one dataset to the other, however, did not reveal decoding levels above chance, calling into question the neurophenomenological similarities between breathwork and DMT. The findings within this thesis contribute to the neuroscience of consciousness in two ways. First, it strengthens the understanding of the neural and experiential changes that DMT and breathwork can induce, states that remain understudied within the context of cognitive neuroscience. Second, the application of TET, and the associated computational analyses applied, demonstrably bridges the gap both between experience and the brain and between distinct ASCs, permitting the extensive evaluation of neurophenomenological substates that ASCs can induce.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2025

Author dc:creator

• Lewis-Healey, Evan

Advisors dc:contributor.advisor

• Bekinschtein, Tristan
• Canales-Johnson, Andres

• Breathwork
• Cognitive Neuroscience
• Consciousness
• EEG
• Neurophenomenology
• Psychedelics

Licence

• https://www.repository.cam.ac.uk/bitstreams/e86772a4-9c47-4384-bde2-ad95d41e825e/download
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.122136

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/390583