Neuroimage
January 29, 2021
Beatrice M. Jobst, Selen Atasoy, Adrián Ponce-Alvarez et al.
37 citations
After taking LSD, the brain's dynamics become less stable and more diverse in response to perturbations. Using a whole-brain computational model fitted to fMRI data from individuals under LSD or placebo, researchers simulated external disruptions to different brain regions. They measured recovery time with the Perturbational Integration Latency Index (PILI). Globally, LSD caused consistently higher PILI values, indicating a shift further from stable equilibrium. Locally, the largest differences appeared in the limbic, visual, and default mode networks. LSD also increased variability of PILI across brain regions, suggesting greater response diversity. These findings reveal brain-wide dynamical changes underlying the psychedelic state and suggest potential clinical applications for psychiatric disorders.
PLoS Computational Biology
February 1, 2023
Giulio Ruffini, Giada Damiani, Diego Lozano-Soldevilla et al.
28 citations
Brain dynamics under LSD become more disordered and complex, moving further from the critical point that characterizes healthy brain function. Using Ising spin models fitted to fMRI data from fifteen participants, the authors show that LSD reduces interhemispheric connectivity, especially between corresponding regions in opposite hemispheres. Ising temperatures were significantly higher under LSD than placebo, indicating a shift into a more disordered (paramagnetic) state. Algorithmic complexity of brain activity, measured by block decomposition, correlated with both Ising temperature and condition, supporting the entropic brain hypothesis that psychedelics increase neural disorder.
bioRxiv
August 29, 2022
Giulio Ruffini, Giada Damiani, Diego Lozano-Soldevilla et al.
5 citations
preprint
Using fMRI data from fifteen people who took LSD or a placebo, researchers modeled brain dynamics with an Ising spin model to test whether psychedelics push the brain into a more disordered state. LSD increased the Ising temperature of brain activity, moving it further away from a critical point (the edge between order and disorder) into a more disordered, paramagnetic phase. This shift was accompanied by a decrease in interhemispheric connectivity, especially between corresponding regions in the two hemispheres. Algorithmic complexity of brain signals also increased with LSD. The findings suggest LSD loosens homotopic connections, driving the brain into a more flexible, complex state, consistent with theories that psychedelics increase neural entropy.
bioRxiv (Cold Spring Harbor Laboratory)
November 7, 2024
Lorenzo Pasquini, Jakub Vohryzek, Anira Escrichs et al.
4 citations
preprint
Psilocybin induces fast and sustained improvements in mental well-being, yet its long-term mechanisms are not fully understood. Four weeks after a full dose, fronto-striatal-thalamic (FST) circuitry—involved in goal-directed behavior and motivation—shows increased dynamic activity and flexibility in healthy volunteers. Computational modeling indicates that reduced structural constraints on functional dynamics cause this increased flexibility. Long-term changes include increased bottom-up and reduced top-down information flow, mediated by serotonergic (5-HT2A) and dopaminergic (D2) receptor systems. This functional re-organization of FST circuits may represent a common mechanism underlying clinical improvements across neuropsychiatric disorders such as substance abuse, major depression, and anorexia.
bioRxiv Preprint Server
January 5, 2021
Beatrice M. Jobst, Selen Atasoy, Adrián Ponce-Alvarez et al.
1 citation
preprint
LSD alters brain dynamics by shifting the brain's global working point further from a stable equilibrium, as shown by consistently higher Perturbational Integration Latency Index (PILI) values after intake. Using a whole-brain computational model perturbed in silico, the largest differences were found in the limbic, visual, and default mode networks. Greater variability of PILI values across brain regions under LSD indicates higher response diversity to external perturbations. These findings provide insights into the brain-wide dynamical changes underlying the psychedelic state and suggest possible clinical applications for psychiatric disorders.
Hum Brain Mapp
July 1, 2026
Lorenzo Pasquini, Jakub Vohryzek, Anira Escrichs et al.
A computational model predicts that a single dose of psilocybin can produce lasting changes in the dynamic activity and effective connectivity of fronto-striatal-thalamic brain circuits. The modeling suggests that psilocybin may strengthen connectivity between the prefrontal cortex and striatum while altering thalamic gating, effects that persist beyond the acute drug experience. These changes could underlie the sustained therapeutic benefits observed in clinical settings, such as reduced depressive symptoms and increased psychological flexibility. The findings provide a mechanistic framework for understanding how psilocybin induces long-term neural plasticity and highlight potential circuit targets for treating psychiatric disorders.
Network neuroscience (Cambridge, Mass.)
January 1, 2022
Athena Demertzi, Aaron Kucyi, Adrián Ponce-Alvarez et al.
Anticorrelations between the default mode network and other brain regions are proposed as a physiological marker of preserved consciousness. The article argues that these anticorrelations express the brain's capacity for segregation—selective functional connectivity between areas—mediated by neural inhibition that regulates global and local inhibitory activity. While other mechanisms may also produce anticorrelations, neural inhibition helps explain how network metastability is disrupted when local and global neural balance is altered. The authors suggest that if the brain cannot host anticorrelations, the individual likely lacks subjective experience. This link may aid understanding of consciousness and guide interventions for consciousness disorders where anticorrelations are affected.