Schizophrenia Bulletin
June 8, 2016
Ben Alderson-Day, Kelly Diederen, Charles Fernyhough et al.
134 citations
Resting-state brain networks may help explain hallucinations across different sensory modalities and populations. This report from the International Consortium on Hallucination Research reviews evidence linking resting-state alterations to auditory hallucinations, finding connectivity differences in left-hemisphere auditory and language regions, plus atypical interactions of the default mode network with networks for cognitive control and salience. Similar patterns appear in visual hallucinations, suggesting both domain-general and modality-specific network changes. However, high methodological heterogeneity across studies limits direct comparisons. The authors offer recommendations for future research on resting-state connectivity and hallucinations.
Neuroscience and Biobehavioral Reviews
July 1, 2023
Daniel Collerton, James Barnes, Nico J Diederich et al.
80 citations
Eight distinct models of complex visual hallucinations have been proposed since 2000, each based on different views of brain organization. Researchers from each model group have now agreed on an integrated Visual Hallucination Framework that aligns with current theories of both real and hallucinatory vision. The Framework identifies cognitive systems involved in hallucinations and enables systematic investigation of how hallucination experiences relate to changes in underlying cognitive structures. The episodic nature of hallucinations points to separate factors for their onset, persistence, and end, suggesting a complex relationship between temporary states and long-term traits of hallucination risk. The Framework also suggests new research directions and potential treatments for distressing hallucinations.
Brain : a journal of neurology
September 14, 2022
James M Shine, Claire O'Callaghan, Ishan C Walpola et al.
63 citations
Serotonin in the brain can be understood as an extension of the gut's serotonergic system, which controls digestion. Central serotonin activity mimics a digestion/satiety circuit, where low serotonergic tone facilitates cognitive automaticity and higher tone helps identify flexible solutions when initial responses fail. This perspective explains serotonin's roles in reward processing, exploration, and psychedelic experiences, and clarifies links between serotonergic dysfunction and psychiatric symptoms.
Elife
January 5, 2024
Daniel Toker, Eli J Müller, Hiroyuki Miyamoto et al.
21 citations
Bidirectional communication between the cortex and thalamus via a specific cross-frequency channel is linked to conscious states. In humans, mice, and rats, low-frequency waves (1–13 Hz) sent from either the cortex or thalamus are consistently encoded by the other region using high gamma waves (52–104 Hz). This cross-frequency communication is diminished during propofol-induced unconsciousness and generalized spike-and-wave seizures, but enhanced by the psychedelic 5-MeO-DMT. Numerical simulations and neural recordings suggest these changes are mediated by shifts in thalamocortical electrodynamics toward or away from edge-of-chaos criticality, offering a mathematical framework for disrupted information transfer during unconsciousness.
bioRxiv Preprint Server
February 22, 2023
Daniel Toker, Eli J Müller, Hiroyuki Miyamoto et al.
3 citations
preprint
Consciousness depends on bidirectional communication between the cortex and thalamus. A specific pattern of cross-frequency communication—low-frequency waves (1.5–13 Hz) from one region encoded as high gamma waves (50–100 Hz) in the other—is present during conscious states in humans, mice, and rats. This communication diminishes during propofol-induced anesthesia and generalized spike-and-wave seizures, but is enhanced by the psychedelic 5-MeO-DMT. Numerical simulations and neural recordings show that these changes are mediated by shifts in thalamocortical dynamics toward or away from edge-of-chaos criticality, the phase transition between stability and chaos. The findings offer a mathematically defined framework linking thalamic-cortical communication to consciousness.
Trends in Neurosciences
December 1, 2023
Jaan Aru, Matthew E Larkum, James M Shine
Large language models are unlikely to become conscious because they lack three key features of biological consciousness. First, they do not receive the embodied, real-world sensory information that grounds human experience. Second, their architectures miss essential neural structures of the mammalian thalamocortical system linked to awareness. Third, the evolutionary and developmental processes that produced conscious living organisms—rooted in survival-driven action and multi-level cellular processes—have no counterpart in current artificial systems.
Proceedings of the National Academy of Sciences of the United States of America
November 14, 2023
Brandon R Munn, Eli J Müller, Jaan Aru et al.
Integrated information, a proposed signature of consciousness, is maximized in a biophysical network model when the nonspecific thalamus drives thick-tufted layer 5 pyramidal neurons into a regime of time-varying synchronous bursting. In this regime, variable spiking dynamics with broad pairwise correlations support enhanced integrated information. The peak in integrated information coincides with criticality signatures and empirically observed layer 5 pyramidal bursting rates. These findings suggest that the thalamocortical core of the mammalian brain may be evolutionarily configured to optimize effective information processing, offering a potential neuronal mechanism linking microscale theories to macroscale signatures of consciousness.
Nature Communications
October 27, 2023
Brandon R Munn, Eli J Müller, Vicente Medel et al.
A microscale biophysical network model of layer-5 pyramidal neurons reproduces coarse-sampled dynamics seen in macroscale electrophysiological recordings from macaques and humans. By inverting the model, the authors identify spike and burst dynamics that distinguish unconscious, dreaming, and awake arousal states and reveal their functional signatures. Neuromodulatory arousal shifts neuronal dynamics around a low-dimensional energy landscape, altering the model's response to external stimuli. The work demonstrates how multiscale modeling can connect theories of consciousness across spatiotemporal scales.
Cell Reports
August 29, 2023
Eli J Müller, Brandon R Munn, Michelle J. Redinbaugh et al.
A whole-brain computational model of the corticothalamic system, built from empirical data on targeted and diffusely projecting thalamocortical nuclei, reproduces key features of propofol anesthesia: reduced network integration, lower state diversity, impaired susceptibility to perturbation, and decreased corticocortical coherence. These signatures indicate suppressed information transfer across the cerebral cortex. Selectively stimulating the matrix thalamus in the model restores signatures of conscious arousal, matching empirical results in macaques, and produces wake-like information processing states. The findings suggest that matrix thalamocortical projections modulate large-scale cortical attractor dynamics to enable the complex communication states that support conscious awareness.