The flattening of spacetime hierarchy of the -dimethyltryptamine brain state is characterized by harmonic decomposition of spacetime (HADES) framework.
Jakub Vohryzek, Joana Cabral, Christopher Timmermann, Selen Atasoy, Leor Roseman, David J Nutt, Robin L Carhart-Harris, Gustavo Deco, Morten L Kringelbach
Author Information
Jakub Vohryzek: Centre for Eudaimonia and Human Flourishing, Linacre College, Department of Psychiatry, University of Oxford, Oxford OX3 9BX, UK. ORCID
Joana Cabral: Centre for Eudaimonia and Human Flourishing, Linacre College, Department of Psychiatry, University of Oxford, Oxford OX3 9BX, UK.
Christopher Timmermann: Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London SW7 2AZ, UK. ORCID
Selen Atasoy: Centre for Eudaimonia and Human Flourishing, Linacre College, Department of Psychiatry, University of Oxford, Oxford OX3 9BX, UK.
Leor Roseman: Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London SW7 2AZ, UK.
David J Nutt: Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London SW7 2AZ, UK.
Robin L Carhart-Harris: Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London SW7 2AZ, UK.
Gustavo Deco: Center for Brain and Cognition, Computational Neuroscience Group, Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona 08005, Spain.
Morten L Kringelbach: Centre for Eudaimonia and Human Flourishing, Linacre College, Department of Psychiatry, University of Oxford, Oxford OX3 9BX, UK. ORCID
The human brain is a complex system, whose activity exhibits flexible and continuous reorganization across space and time. The decomposition of whole-brain recordings into harmonic modes has revealed a repertoire of gradient-like activity patterns associated with distinct brain functions. However, the way these activity patterns are expressed over time with their changes in various brain states remains unclear. Here, we investigate healthy participants taking the serotonergic psychedelic -dimethyltryptamine (DMT) with the Harmonic Decomposition of Spacetime (HADES) framework that can characterize how different harmonic modes defined in space are expressed over time. HADES demonstrates significant decreases in contributions across most low-frequency harmonic modes in the DMT-induced brain state. When normalizing the contributions by condition (DMT and non-DMT), we detect a decrease specifically in the second functional harmonic, which represents the uni- to transmodal functional hierarchy of the brain, supporting the leading hypothesis that functional hierarchy is changed in psychedelics. Moreover, HADES' dynamic spacetime measures of fractional occupancy, life time and latent space provide a precise description of the significant changes of the spacetime hierarchical organization of brain activity in the psychedelic state.
