Human EEG shows long-range temporal correlations of oscillation amplitude in Theta, Alpha and Beta bands across a wide age range

Objective: Long-range temporal correlations (LRTC) of EEG amplitude fluctuations in adults reveal power-law statistics and have been interpreted within the framework of self-organized criticality (SOC). In physical systems states of self-organized criticality showing power-law statistics take time to develop. In this paper we have sought evidence for the idea that brain development tends towards SOC through examining the hypothesis that during normal human development a power law behaviour of EEG oscillations is approached with increasing chronological age. Methods: We examined EEGs from central and parietal electrodes in 36 subjects aged between 0 and 660 months during performance of a steady wrist extension task with their dominant hand and applied spectral and detrended fluctuation analysis in 36 subjects to assess long-range temporal correlations of oscillation amplitude in the Theta, Alpha and Beta frequency bands. Results: Our data indicate that at all subject ages power-law statistics dominate the records at Alpha, Beta and Theta frequencies. Small consistent effects of chronological age were detected for amplitude fluctuations at Theta and Beta frequencies. Conclusions: The data suggest that the scale-free nature of EEG LRTCs is a feature from early childhood through to maturity but that there are changes in the magnitude of these effects with age. Significance: This study is the first to have explored long-range temporal correlations over a wide range of chronological age. (C) 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.