Cerebral cortex (New York, N.Y. : 1991)
June 30, 2020
Andrés Canales-Johnson, Alexander J Billig, Francisco 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.
Cerebral cortex (New York, N.Y. : 1991)
August 1, 2024
Evan Lewis-Healey, Enzo Tagliazucchi, Andrés Canales-Johnson et al.
27 citations
Intentional breathing techniques (breathwork) can induce altered states of consciousness similar to those produced by psychedelics. By tracking subjective experiences moment-by-moment alongside portable EEG recordings across 301 sessions from 14 novice participants, researchers found that psychedelic-like experiences—especially intense bliss—corresponded with increased neural complexity (Lempel-Ziv complexity) and changes in the aperiodic exponent of brain activity, but not with alpha brainwave power. These non-linear neural features map onto both broad positive experiences and specific psychedelic-like states, suggesting breathwork alters consciousness through mechanisms distinct from simple relaxation or meditation.
The European journal of neuroscience
March 1, 2022
Claudia Pascovich, Santiago Castro-Zaballa, Pedro A M Mediano et al.
16 citations
Neural complexity, measured by the Lempel-Ziv (LZ) compression algorithm, is lowest during NREM sleep and similar during REM sleep and wakefulness in cats with intracranial electrodes. Under subanaesthetic doses of ketamine (5, 10, and 15 mg/kg), complexity follows an inverted U-shaped curve in some electrodes, primarily in prefrontal cortex, rising at low doses and falling as doses approach anaesthetic levels. The variability in the ketamine dose-response curve across cats and cortices was larger than across sleep stages, highlighting differential local dynamics. These results replicate findings in humans and other species, showing neural complexity is sensitive to changes in conscious state.
Neuroscience of Consciousness
July 12, 2024
P. Pérez, D. Manasova, B. Hermann et al.
A framework is introduced that characterizes neuronal markers of consciousness along two dimensions: how well they distinguish conscious from non-conscious states (x-axis) and how well they distinguish different conscious contents (y-axis). Using electroencephalography markers of connectivity, complexity, and spectral summaries, the framework is applied to healthy participants during a nap and patients with disorders of consciousness for the state dimension, and to healthy participants in visual awareness and auditory local-global paradigms for the content dimension. Separate clusters of markers with correlated and anticorrelated dynamics emerge, highlighting the complex relationship between the state and content of consciousness and the need to consider them together.
Frontiers in psychology
January 1, 2015
Valdas Noreika, Andrés Canales-Johnson, Justin Koh et al.
During the transition from relaxation to drowsiness, people often experience hypnagogic phenomena such as perceptual imagery or linguistic intrusions—sudden, unpredictable anomalies in inner speech. In a single participant across 10 EEG sessions, drowsiness depth (measured by Hori stages) increased in the 20 seconds before reporting such an experience, and EEG Dimension of Activation values decreased, indicating rapid changes in brain predictability. Linguistic intrusions were associated with higher alpha and gamma power over the left hemisphere, while perceptual imagery corresponded to higher beta power over the right hemisphere. These results suggest that the modality and incongruence of hypnagogic experiences have distinct EEG signatures, and sleep onset offers a way to study the neural basis of consciousness fragmentation in healthy individuals.
Frontiers in Psychology
May 22, 2014
Srivas eChennu, Tristan A Bekinschtein
The interplay between top-down and bottom-up attention and consciousness is often examined during sleep, sedation, and disorders of consciousness such as the vegetative state (VS) and minimally conscious state (MCS). The auditory oddball paradigm, which elicits the mismatch negativity (MMN) and P300 event-related potentials, is a common tool for assessing cognitive processing in these contexts. The P300 wave can be separated into the earlier P3a, linked to bottom-up attention, and the later P3b, linked to top-down attention. Emerging evidence from healthy volunteers and patients reveals dissociations between attention and awareness across these states, highlighting neurophysiological and cognitive parallels and differences that inform theoretical frameworks.