Human Brain Mapping
January 28, 2018
Jianfeng Zhang, Zirui Huang, Yali Chen et al.
70 citations
During anesthetic-induced unconsciousness, two temporal features of brain activity—long-range temporal correlations (measured by power-law exponent) and temporal variability (measured by standard deviation)—both decrease globally across the brain compared to wakefulness. The spatial relationship between these two features becomes altered, or 'decoupled,' primarily due to changes in the spatial pattern of long-range temporal correlations rather than temporal variability. This suggests that the topographical organization of long-range temporal correlations is crucial for maintaining optimal neural dynamics during normal consciousness, supporting the temporo-spatial theory of consciousness.
British journal of anaesthesia
March 1, 2024
Zhenhu Liang, Yu Chang, Xiaoge Liu et al.
10 citations
Information integration and brain network measures derived from EEG can distinguish conscious from unconscious states induced by three different anaesthetics. In 72 participants given propofol, dexmedetomidine, or ketamine until they lost responsiveness, permutation cross mutual information (PCMI) within frontal, parietal, and occipital regions decreased during unresponsiveness—for example, frontal within-area PCMI fell from 0.54 to 0.46. Alpha-band PCMI in the frontal region and gamma-band PCMI in posterior areas also dropped. Network analyses showed reduced clustering coefficients and nodal efficiency in frontal, parietal, and occipital areas, while normalized path length increased in delta, theta, and gamma bands, indicating impaired global integration. The three drugs produced similar changes, suggesting a common EEG signature of anaesthesia-induced unconsciousness.
Human brain mapping
February 1, 2023
Siyang Li, Yali Chen, Peng Ren et al.
Brain regions that are both highly connected to other hub regions (rich-club) and variable in their module membership across time are candidates for the neural correlates of consciousness. In resting-state fMRI data from 21 subjects, such regions were located in prefrontal and temporoparietal cortices. Dynamic analysis revealed two recurring brain states: one dominated by these candidate regions and the other by primary sensory/motor regions. The candidate-dominated state was temporally more stable, suggesting it sustains conscious content. The functional connectedness and modular variability of these candidates decreased with propofol-induced loss of consciousness.
Frontiers in systems neuroscience
January 1, 2021
Yali Chen, Jun Zhang
Consciousness is thought to arise from specific neuronal processes, but leading theories like information integration theory, global neuronal workspace theory, and the temporospatial theory focus on neural mechanisms while neglecting their energetic-metabolic basis. Drawing on findings from loss of consciousness due to sleep, general anesthesia, and vegetative state/unresponsive wakeful syndrome in humans and animals, the authors propose that energetic-metabolic processes involving ATP, glucose, and γ-aminobutyrate/glutamate are essential for the functional connectivity of normal brain networks that enables consciousness. They describe these as energetic-metabolic predispositions of consciousness, complementing existing theories centered on neural correlates.