s . bi o - ph ] 3 1 M ar 1 99 8 EXPERIMENTAL EVIDENCE FOR A POWER LAW IN ELECTROENCEPHALOGRAPHIC α – WAVE DYNAMICS

We perform an experimental study of the time behavior of the α-wave events occuring in human electroencephalographic signals. We find that the fraction of the time spent in an α-burst of time size τ exhibits a scaling behavior as a function of τ. The corresponding exponent is equal to 1.75±0.13. We therefore point out the existence of a new power law appearing in physiology. Furthermore, we show that our experimental result may have a possible explanation within a class of Self-Organized Critical (SOC) models recently proposed by Boettcher and Paczuski. In particular, one of these models, when properly re-interpreted, seems to be consistent both with our experimental result and a commonly accepted physiological description of the possible origin of α-wave events.