Spatio-temporal analysis of monofractal and multifractal properties of the human sleep EEG.
Fractality is a common property in nature. It can also be observed in time series representing dynamics of complex processes. Therefore fractal analysis could be a useful tool to describe the dynamics of brain electrical activities in physiological and pathological conditions. In this study, we carried out a spatio-temporal analysis of monofractal and multifractal properties of whole-night sleep EEG recordings. We estimated the Hurst exponent (H) and the range of fractal spectra (dD) in 10 healthy subjects. We found higher H values during NREM4 compared to NREM2 and REM in all electrodes. Measure dD showed an opposite trend. Differences of H and dD between NREM2 and REM reached significancy at circumscribed regions only. Our results contribute to a deeper understanding of the fractal nature of brain electrical activities and may have implications for automatic classification of sleep stages.
Weiss
Béla
B
Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary. weiss@itk.ppke.hu
Clemens
Zsófia
Z
Bódizs
Róbert
R
Vágó
Zsuzsanna
Z
Halász
Péter
P
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D016477:Artifacts; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D017709:Fractals; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods*; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000502:physiology*; D013269:Stochastic Processes; D013997:Time Factors; D055815:Young Adult