Diminished functional gradient of the precuneus during altered states of consciousness
Dian Lyu, Ram Adapa, Robin Carhart-Harris, Leor Roseman, Adrian M. Owen, Lorina Naci, David K. Menon, Emmanuel A. Stamatakis
bioRxiv December 17, 2024 preprint DOI: 10.1101/2024.12.17.628862 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study |
|---|---|
| Population | Human brains |
| Topics | Meditation Altered states of consciousness |
| Keywords | Consciousness Brain research Altered states |
| Key findings | Connectivity differences between the DMN and FPCN along the dorsal-ventral axis in the posterior precuneus are continuous and form functional gradients that flatten in altered states of consciousness. |
Abstract
Abstract The relationship between the default mode network (DMN) and task-positive networks, such as the frontoparietal control network (FPCN), is a prominent feature of functional connectivity (FC) in the human brain. This relationship is primarily anticorrelated at rest in healthy brains and is disrupted in altered states of consciousness. Although the DMN and FPCN seem to perform distinct and even opposing roles, they are anatomically adjacent and exhibit ambiguous boundaries. To test the hypothesis that the DMN-FPCN distinction manifests probabilistically rather than having absolute anatomical boundaries, we examined the differences in FC along the dorsal-ventral (d-v) axis in the posterior precuneus (PCu), which serves a convergence zone between the DMN and FPCN. Our findings indicate that the connectivity differences along this axis are continuous as characterized by linear slopes. Notably, these linear relationships (i.e., functional gradients of the precuneus/FGp) are present only within the territories of the DMN and FPCN, respectively associating with positive and negative slopes. Furthermore, the gradient is functionally relevant, as its spatial configurations change in specific ways in altered states of consciousness (ASC): the magnitude of FGp is similarly impaired across different types of ASC, while the spatial entropy of FGp differs between psychedelic and sedative states. These results suggest that the DMN and FPCN, while appearing distinct, may originate from a single, integrated mechanism. Significance Statement This research provides new insights into the brain’s functional organization underlying human conscious states by examining the relationship between two large-scale networks: the default mode network (DMN) and the frontoparietal control network (FPCN). These networks, which are attuned to handle internal and external information respectively, are often viewed as oppositional. However, our findings indicate they form an integrated system with continuous connectivity. We identified the posterior precuneus as a key convergence point, revealing a gradient of connectivity between the two networks. This gradient flattens during altered states of consciousness induced by psychedelics or sedatives, showing a loss of functional differentiation between the DMN and FPCN.
Comparable studies
Other observational and cohort studies on altered states of consciousness, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Neural correlates of the DMT experience assessed with multivariate EEG. 6 female, 7 male human participants | 2019 | Observational cohort | n = 13 |
| Measures of entropy and complexity in altered states of consciousness Subjects during resting wakefulness, different sleep stages, and epileptic seizures | 2017 | Observational study | |
| Altered States of Consciousness and Short-Term Psychological After-Effects Induced by the First Time Ritual Use of Ayahuasca in an Urban Context in Brazil First-time ayahuasca users in Santo Daime and União do Vegetal rituals | 2005 | Observational cohort | n = 28 |
| Quantifying arousal and awareness in altered states of consciousness using interpretable deep learning Healthy individuals during sleep, individuals under general anesthesia, and patients... | 2022 | Observational cohort | n = 71 |
| Subanaesthetic ketamine and altered states of consciousness in humans Human volunteers | 2018 | Observational study | n = 15 |
Citations in the library
Cites 15
- The precuneus/posterior cingulate cortex plays a pivotal role in the default mode network: Evidence from a partial correlation network analysis Neuroimage June 13, 2008
- Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin Proceedings of the National Academy of Sciences January 23, 2012
- REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics Pharmacological Reviews June 20, 2019
- Breakdown of within- and between-network Resting State Functional Magnetic Resonance Imaging Connectivity during Propofol-induced Loss of Consciousness Anesthesiology September 30, 2010
- Deep posteromedial cortical rhythm in dissociation Nature September 16, 2020
and 10 more in the library