Self-organized criticality (SOC) is a property of neural systems that may serve as a unifying framework for theories of consciousness. A review of 71 publications from 1998 to 2021 found that annual citations increased steadily; original articles made up 50.7% and reviews or theoretical articles 43.6%. Human data were reported in 16 studies, animal data in 7, and computational models in 12. EEG/MEG studies used diverse analytical tools—detrended fluctuation analysis, pair correlation function, neuronal avalanche parameters, and spectral exponent—to assess criticality. Critical dynamics align with global workspace theory and integrated information theory, but the small number of experimental studies and heterogeneity of methods limit generalizability.
Meditation states produce distinct patterns of brain activity measurable by nonlinear complexity and critical dynamics. Highly proficient meditators were measured with EEG during three meditation conditions (thoughtless emptiness, presence monitoring, focused attention) and compared to resting and reading. Compared to eyes-closed rest, emptiness and focused attention showed higher entropy and fractal dimension, while long-range temporal correlations decreased across all meditation conditions. The critical exponent was lowest for focused attention and reading. Gamma-band activity, global power spectral density, and sample entropy best discriminated among states (accuracy 0.83–0.98, 0.78–0.96, and 0.86–0.90 respectively). Meditation states can be quantified by neuronal complexity, long-range temporal correlations, and power law distributions in neuronal avalanches.
Brain activity in the resting state shows scale-free, critical dynamics balanced between order and disorder, but a direct link to cognition has been missing. Using MEG recordings during mindfulness meditation, the authors found that scale-free near-critical dynamics originated only from broad-band high-frequency activity above 100 Hz, which is associated with action potential firing. During meditation, avalanche dynamics shifted toward a critical point by reducing neural noise, and the topography of avalanches differed from rest. Self-regulated attention during meditation can serve as a control parameter for criticality in scale-free brain dynamics.