Communications biology
January 28, 2023
Andrea I Luppi, Jakub Vohryzek, Morten L Kringelbach et al.
98 citations
Consciousness depends on how tightly brain function follows the brain's physical wiring. Using MRI scans, researchers measured structure-function coupling across spatial scales in people who were unconscious from anesthesia or brain injury and in people under psychedelics (LSD or ketamine). During loss of consciousness, function more closely tracked the brain's structural connections, a signature that could distinguish behaviorally similar brain-injured patients and detect covert consciousness. In contrast, psychedelics decoupled function from structure, and this decoupling correlated with physiological and subjective scores. The findings suggest that connectome harmonic decomposition reveals how neuromodulation and network architecture jointly shape consciousness.
Cogn Neuropsychiatry
February 6, 2011
James W. Moore, Danielle C. Turner, Philip R. Corlett et al.
64 citations
Ketamine, a drug that induces temporary psychosis-like symptoms, increased the sense of agency in healthy adults, mimicking the exaggerated action-effect binding seen in schizophrenia. In a small experiment, 14 participants given low-dose ketamine showed greater compression of time between their actions and outcomes compared to placebo. The size of this effect correlated with unusual bodily experiences caused by the drug. The findings suggest ketamine can reproduce certain agency disturbances characteristic of schizophrenia, and that these changes are linked to broader alterations in body awareness.
bioRxiv
December 17, 2024
Dian Lyu, Ram Adapa, Robin L. Carhart-Harris et al.
preprint
The default mode network (DMN) and frontoparietal control network (FPCN), typically anticorrelated at rest in healthy brains, show continuous rather than absolute anatomical boundaries in the posterior precuneus. Connectivity differences along the dorsal-ventral axis follow linear slopes, forming functional gradients that exist only within each network's territory. These gradients flatten in altered states of consciousness (ASC), with the gradient magnitude similarly impaired across different ASC types, while spatial entropy differs between psychedelic and sedative states. The findings suggest the DMN and FPCN, though appearing distinct, may originate from a single integrated mechanism, and the loss of functional differentiation between them characterizes altered conscious states.
bioRxiv Preprint Server
April 12, 2021
Peter Coppola, Lennart R.b. Spindler, Andrea I. Luppi et al.
preprint
The diversity of brain dynamics within small-world network topology, measured as sample entropy (dSW-E), consistently predicts levels of awareness across sedation and disorders of consciousness, even after accounting for underlying functional connectivity dynamics. Both subcortical and cortical areas show predictive value, but subcortical regions exhibit higher and more robust effect sizes. The dynamic reorganization of the functional information architecture, especially in the subcortex, emerges with awareness and offers explanatory power beyond the complexity of dynamic functional connectivity alone.
Communications biology
November 3, 2022
Peter Coppola, Judith Allanson, Lorina Naci et al.
Consciousness is associated with short-term brain connectivity transitions that are less predictable, quicker, but on average more constant than those in unconscious states. By combining modern consciousness theories with phenomenology and dynamical systems theory, the authors created an individual-specific landscape of brain connectivity dynamics as a proxy for the stream of consciousness. They found that temporally-specific connectivity states are less easily describable by network patterns distant in time, suggesting a richer space of possible states. The cortex, cerebellum, and subcortex all display consciousness-relevant dynamics.