Evolutionary Advantages of Stimulus-Driven EEG Phase Transitions in the Upper Cortical Layers.

EEG recordings in humans and other mammals show beta/gamma oscillations (20-80 Hz) that self-organize into spatio-temporal structures recurring at theta/alpha rates (4-12 Hz), correlating with sensory stimuli and reinforcement contingencies. These structures repeatedly collapse, generating laterally propagating phase gradients (phase cones) that may be neural signatures of transient perceptual experiences. According to neuropercolation theory, waking brains operate as non-equilibrium thermodynamic systems at the edge of criticality, undergoing repeated phase transitions. Long-range axonal connections and metabolic processes regulate this critical dynamics. This cortical operating style may optimize a tradeoff between rapid adaptation and stable self-organization, offering Darwinian benefits.

Study at a glance

Abstract

Spatio-temporal brain activity monitored by EEG recordings in humans and other mammals has identified beta/gamma oscillations (20-80 Hz), which are self-organized into spatio-temporal structures recurring at theta/alpha rates (4-12 Hz). These structures have statistically significant correlations with sensory stimuli and reinforcement contingencies perceived by the subject. The repeated collapse of self-organized structures at theta/alpha rates generates laterally propagating phase gradients (phase cones), ignited at some specific location of the cortical sheet. Phase cones have been interpreted as neural signatures of transient perceptual experiences according to the cinematic theory of brain dynamics. The rapid expansion of essentially isotropic phase cones is consistent with the propagation of perceptual broadcasts postulated by Global Workspace Theory (GWT). What is the evolutionary advantage of brains operating with repeatedly collapsing dynamics? This question is answered using thermodynamic concepts. According to neuropercolation theory, waking brains are described as non-equilibrium thermodynamic systems operating at the edge of criticality, undergoing repeated phase transitions. This work analyzes the role of long-range axonal connections and metabolic processes in the regulation of critical brain dynamics. Historically, the near 10 Hz domain has been associated with conscious sensory integration, cortical "ignitions" linked to conscious visual perception, and conscious experiences. We can therefore combine a very large body of experimental evidence and theory, including graph theory, neuropercolation, and GWT. This cortical operating style may optimize a tradeoff between rapid adaptation to novelty vs. stable and widespread self-organization, therefore resulting in significant Darwinian benefits.