Neuroimage
April 11, 2020
Ignacio Perez-Ipina, Patricio Donnelly Kehoe, Morten L. Kringelbach et al.
81 citations
A semi-empirical model combining fMRI data, structural connectivity, and anatomically-informed priors shows that brain states during the wake-sleep cycle are better described by multiple dimensions rather than a single continuum. The best fit used priors based on functionally coherent networks, dividing the cortex into regions with opposite dynamics: frontoparietal regions approached a noise-driven bifurcation from fixed-point dynamics, while sensorimotor regions approached a bifurcation from oscillatory dynamics. Sleep onset involved subcortical deactivation with low correlation, reversed in deeper stages. Periodic forcing simulating external perturbations identified key regions for wakefulness recovery. The model characterizes sleep as having diminished perceptual gating but latent capacity for rapid arousal.
Cerebral cortex (New York, N.Y. : 1991)
June 30, 2020
Andrés Canales-Johnson, Alexander J Billig, Francisco A Olivares et al.
51 citations
During auditory bistable perception, a sequence of tones can be heard either as a single stream (integrated percept) or as two parallel streams (differentiated percept). Neural recordings showed that when perceptual alternations arose spontaneously, the integrated percept corresponded to increased neural information integration and decreased neural information differentiation across frontoparietal regions, while the differentiated percept showed the opposite pattern. When perception was driven by an external change in the sound stream, neural oscillatory power distinguished between percepts but information measures did not. The findings demonstrate that integration and differentiation of conscious perception map onto theoretically motivated neural information signatures, suggesting a direct link between phenomenology and neurophysiology.
Network Neuroscience
January 1, 2022
Josephine Cruzat, Yonatan Sanz Perl, Anira Escrichs et al.
28 citations
Psychedelic drugs like LSD and psilocybin may treat neuropsychiatric disorders by dose-dependently altering the brain's functional hierarchy—the organization of neural activity across regions. Using a turbulence framework that measures local synchronization (vorticity) in both space and time, researchers found that both drugs produce consistent and distinct effects, particularly compressing the default mode network, a higher-level network. These findings support the hypothesis that psychedelics modulate the functional hierarchy and provide a quantitative comparison of how LSD and psilocybin change brain dynamics, with implications for therapeutic use.
Translational Psychiatry
July 27, 2024
Rubén Herzog, Florentine Marie Barbey, Md Nurul Islam et al.
13 citations
Ketamine increases redundancy in brain dynamics—copies of the same information retrievable from three or more electrodes—most notably in the alpha frequency band, as measured by portable low-density EEG. In a double-blind crossover trial with 30 male adults, racemic ketamine compared to saline infusion produced greater redundancy during resting state, linked to dissociative shifts in consciousness. During an auditory oddball task, the effect was stronger for predictable standard stimuli than for deviant ones. Associations between ketamine's high-order interactions and experiences of derealization were observed, suggesting these measures capture pharmacological alterations in consciousness.
Cortex; a journal devoted to the study of the nervous system and behavior
September 1, 2021
Santiago Alcaide, Jacobo Sitt, Tomoyasu Horikawa et al.
13 citations
Waking up from early sleep involves a two-stage brain process. First, subcortical and sensorimotor structures activate before most cortical regions, followed by rapid whole-brain activation, with frontal regions engaging slightly later. A second, slower stage may then occur, where cortical regions activate before subcortical structures and the cerebellum. This pattern suggests subcortical structures play a key role in initiating and maintaining conscious states.
Research Square
March 21, 2024
Agustin Ibanez, Rubén Herzog, Florentine Barbey et al.
1 citation
Ketamine increases redundancy in brain dynamics, particularly in the alpha frequency band, and this effect is more pronounced during resting state and associated with dissociative experiences. In a double-blinded cross-over design with 30 male adults, racemic ketamine was compared to saline infusion. Higher-order interactions (HOI) computed from EEG data showed that ketamine boosted redundancy, especially for predictable stimuli in an auditory oddball task. These findings suggest that ketamine-induced shifts toward dissociation correlate with increased redundancy in neural signal interactions, highlighting the potential of complexity measures with portable EEG for monitoring pharmacological changes in consciousness.
Neuroscience and Biobehavioral Reviews
June 1, 2026
Agustin Ibanez, Nick Roth, Aaron Colverson et al.
Metaphors have long shaped how scientists conceptualize the mind and brain, from early analogies like hydraulic systems to the modern computer metaphor. This paper proposes music as a new scientific metaphor for understanding brain dynamics and cognitive functions. Unlike static metaphors, music emphasizes continuous adaptation, context-dependence, cultural embedding, and simultaneous engagement with multiple layers of meaning. The authors argue that music's hierarchical structure, temporal complexity, and capacity to integrate multiple processes parallel key features of brain architecture and cognition. Drawing on research in neural oscillations, plasticity, predictive coding, and emotional processing, they illustrate how a musical paradigm can capture the rich interplay of mind and brain across large-scale dynamics, development, consciousness, and affect.
bioRxiv Preprint Server
September 28, 2022
Yonatan Sanz Perl, Carla Pallavicini, Juan Piccinini et al.
preprint
Brain states are often described on a single scale from full consciousness to unconsciousness, but this ignores the complex, high-dimensional nature of brain activity. By combining whole-brain modeling, data augmentation, and deep learning, researchers mapped states of consciousness into a low-dimensional space where distances reflect similarities between states. They found an orderly trajectory from wakefulness to brain-injured patients, with coordinates related to functional modularity and structure-function coupling, both increasing as consciousness is lost. Model perturbations provided a geometric interpretation of state stability and reversibility. The work suggests conscious awareness depends on functional patterns encoded as a low-dimensional trajectory within the vast space of brain configurations.
bioRxiv Preprint Server
July 2, 2020
Yonatan Sanz Perl, Carla Pallavicini, Ignacio Perez-Ipina et al.
preprint
The level of consciousness—how conscious someone is—is often measured by how similar their brain activity is to normal wakefulness. However, this approach misses important information about how stable that state is. Using computer models of the whole brain, the authors show that the stability of a conscious state—how easily it can be disrupted—provides additional, complementary information. They propose a new framework that sorts brain states by both their similarity to wakefulness and their stability, which helps distinguish between different types of unconsciousness: natural sleep, anesthesia, and brain injury. This framework offers a more complete way to characterize and differentiate states of consciousness.
Neuroimage
April 1, 2018
Ezequiel Mikulan, Eugenia Hesse, Lucas Sedeño et al.
Gamma-band neural synchrony is thought to be important for cortical computation and consciousness, but prior evidence has been inconclusive due to methodological issues. By using intracranial EEG in three participants with implanted electrodes, researchers compared high-gamma connectivity (90-120 Hz) during passive wakefulness versus non-REM sleep. Connectivity and graph-theory measures were higher during wakefulness and distinguished the two states better than other frequency bands. This is the first intracranial EEG report of wake-sleep differences in high-gamma activity at both local and distant brain sites, highlighting the technique's value for studying neural correlates of consciousness.
Behavioral and brain functions : BBF
December 23, 2013
Margherita Melloni, Lucas Sedeño, Blas Couto et al.
Long-term and short-term meditators showed lower anxiety and depression than non-meditators, but no improvement in executive function or social cognition, except for lower personal distress scores on empathy. Meditators did not differ from non-meditators in cardiac interoceptive sensitivity, measured by a heartbeat detection task. The authors suggest that mindfulness meditation may not influence cardiac interoception, possibly because awareness of heartbeat sensations is not emphasized in mindfulness or vipassana practice.