Self-Organized Criticality in the Brain

Self-organized criticality (SOC) refers to the ability of complex systems evolve toward a second-order phase transition at which interactions between system components lead scale-invariant events that are beneficial for performance. For last two decades, considerable experimental evidence has accumulated mammalian cortex with its diversity in cell types, interconnectivity, and plasticity might exhibit SOC. Here, we review findings isolated, layered preparations self-organize four dynamical motifs presently identified intact vivo : up-states, oscillations, neuronal avalanches, coherence potentials. During synchronization observed nested theta/gamma oscillations embeds can be by robust power law scaling avalanche sizes slope ?3/2 critical branching parameter 1. This precise coordination, tracked negative transients local field potential (nLFP) spiking activity pyramidal neurons using two-photon imaging, emerges autonomously superficial layers organotypic cultures acute slices, is homeostatically regulated, exhibits separation time scales, reveals unique size vs. quiet dependencies. A subclass potentials, maintenance course propagated synchrony. Avalanches emerge under conditions strong external drive. The balance excitation inhibition (E/I), as well neuromodulators such dopamine, establishes powerful control parameters dynamics. rich repertoire not dissociated cultures, lack differentiation into cortical phenotype expected first-order transition. avalanches provide compelling SOC brain.