Understanding brain states across spacetime informed by whole-brain modelling

Vohryzek, Jakub; Cabral, Joana; Vuust, Peter; Deco, Gustavo; Kringelbach, Morten L.

doi:10.1098/rsta.2021.0247

Cited by 34 publications

(31 citation statements)

References 105 publications

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“…According to the Free Energy Principle and the 'active inference' component that it subsumes, the brain and behaviour (self) organises, or is volitionally organised, to minimise surprising encounters in the world by maximising the reach, reliability and efficiency of its internal models and behavioural schemas, in a fashion that is consistent with Hamilton's principle of 'least action' (Hanc and Taylor, 2004). Building on this, the REBUS model proposes that the entropy-enhancing action of psychedelics works against this imperative -i.e., psychedelics flatten the dynamical global landscape of brain states (Cruzat et al 2022;Vohryzek et al, 2022), allowing for an easier escape from local optima, including ones that may have become excessively reinforced in pathology, but also creating a basal sense of felt uncertainty as the content of consciousness becomes unpredictable and 'enriched' relative to normal waking consciousness (Pollan, 2018).…”

Section: Neuroscience Of Psychedelics: Psychedelics As Destabilisers ...mentioning

confidence: 99%

Pattern Breaking: A Complex Systems Approach to Psychedelic Medicine

Hipólito¹,

Mago²,

Rosas³

et al. 2022

Preprint

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There is growing evidence for the safety and efficacy of psychedelic therapy in mental health care. What is less understood however, is how psychedelics act to yield therapeutic results. In this paper we propose that psychedelics act as destabilisers — both in a psychological and a neurophysiological sense. Our proposed framework builds on the ‘entropic brain’ hypothesis, according to which psychedelics increase the entropy of spontaneous cortical activity and, in parallel, the richness or depth of content of psychological experience. The so-called ‘RElaxed Beliefs Under pSychedelics’ (REBUS) model is a predictive-coding inspired extension to this hypothesis, which states that psychedelics’ entropic action is paralleled by a relaxation of prior assumptions. Here we adopt a complex systems theory (CST) perspective, proposing that psychedelics act as destabilisers of excessively reinforced fixed points — or ‘attractors’ — which translates as the breaking of excessively reinforced or overweighted patterns of thinking or behaving. Our CST approach explains how psychedelic-induced increases in brain entropy destabilise neurophysiological set-points that are synonymous with overweighted priors, thereby augmenting and enriching the account given by REBUS. We believe that this perspective helps inspire conceptualisations of psychedelic psychotherapy — bearing relevance both to the peak psychedelic experience and subsequent sub-acute period of potential recovery. We discuss implications for risk mitigation and treatment optimization in psychedelic medicine.

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Section: Neuroscience Of Psychedelics: Psychedelics As Destabilisers ...mentioning

confidence: 99%

Pattern Breaking: A Complex Systems Approach to Psychedelic Medicine

Hipólito¹,

Mago²,

Rosas³

et al. 2022

Preprint

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show abstract

“…It is well-known that brain states, both healthy and altered, can be characterized by complex emergent spatio-temporal patterns. In Understanding brain states across spacetime informed by whole-brain modelling [173] Vohryzek and coauthors embrace the idea of considering the human brain as a complex system, and they offer a review on how these patterns can be mapped and modeled via non-invasive imaging and whole-brain modeling, with a focus on depression and psychedelics.…”

Section: Summary Of the Theme Issuementioning

confidence: 99%

From the origin of life to pandemics: Emergent phenomena in complex systems

Artime,

De Domenico

2022

Preprint

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When a large number of similar entities interact among each other and with their environment at a low scale, unexpected outcomes at higher spatio-temporal scales might spontaneously arise. This nontrivial phenomenon, known as emergence, characterizes a broad range of distinct complex systems -from physical to biological and social ones -and is often related to collective behavior. It is ubiquitous, from non-living entities such as oscillators that under specific conditions synchronize, to living ones, such as birds flocking or fish schooling. Despite the ample phenomenological evidence of the existence of systems' emergent properties, central theoretical questions to the study of emergence remain still unanswered, such as the lack of a widely accepted, rigorous definition of the phenomenon or the identification of the essential physical conditions that favour emergence. We offer here a general overview of the phenomenon of emergence and sketch current and future challenges on the topic. Our short review also serves as an introduction to the Theme Issue Emergent phenomena in complex physical and socio-technical systems: from cells to societies, where we provide a synthesis of the contents tackled in the Issue and outline how they relate to these challenges, spanning from current advances in our understanding on the origin of life to the large-scale propagation of infectious diseases.

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“…These recurrent metastable substates can be characterized by their probability of occurrence. Beyond the quantitative description of brain states, we wish to understand which brain regions play a prominent role in the recovery from depression after treatment with psilocybin (Vohryzek et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Brain dynamics predictive of response to psilocybin for treatment-resistant depression

Vohryzek

Cabral

Lord

et al. 2022

Preprint

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Psilocybin therapy for depression has started to show promise, yet the underlying causal mechanisms are not currently known. Here we leveraged the differential outcome in responders and non-responders to psilocybin (10mg and 25mg, 7 days apart) therapy for depression - to gain new insights into regions and networks implicated in the restoration of healthy brain dynamics. We used whole-brain modelling to fit the spatiotemporal brain dynamics at rest in both responders and non-responders before treatment. Dynamic sensitivity analysis of systematic perturbation of these models enabled us to identify specific brain regions implicated in a transition from a depressive brain state to a heathy one. Binarizing the sample into treatment responders (>50% reduction in depressive symptoms) versus non-responders enabled us to identify a subset of regions implicated in this change. Interestingly, these regions correlate with in vivo density maps of serotonin receptors 5-HT2A and 5-HT1A, which psilocin, the active metabolite of psilocybin, has an appreciable affinity for, and where it acts as a full-to-partial agonist. Serotonergic transmission has long been associated with depression and our findings provide causal mechanistic evidence for the role of brain regions in the recovery from depression via psilocybin.

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Understanding brain states across spacetime informed by whole-brain modelling

Cited by 34 publications

References 105 publications

Pattern Breaking: A Complex Systems Approach to Psychedelic Medicine

Pattern Breaking: A Complex Systems Approach to Psychedelic Medicine

From the origin of life to pandemics: Emergent phenomena in complex systems

Brain dynamics predictive of response to psilocybin for treatment-resistant depression

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