Does the 1/f frequency-scaling of brain signals reflect self-organized critical states?
Claude Bédard, Helmut Kroger and Alain Destexhe

Physical Review Letters 97: 118102, 2006.

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Many complex systems display self-organized critical states characterized by 1/f frequency scaling of power spectra. Global variables such as the electroencephalogram, scale as 1/f, which could be the sign of self-organized critical states in neuronal activity. By analyzing simultaneous recordings of global and neuronal activities, we confirm the 1/f scaling of global variables for selected frequency bands, but show that neuronal activity is not consistent with critical states. We propose a model of 1/f scaling which does not rely on critical states, and which is testable experimentally.