Quantifying changes in EEG complexity induced by photic stimulation.
OBJECTIVE
This study aims to characterize EEG complexity, measured as the prediction error resulting from nonlinear prediction, in healthy humans during photic stimulation.


METHODS
EEGs were recorded from 15 subjects with eyes closed (EC) and eyes open (EO), during the baseline condition and during stroboscopic photic stimulation (PS) at 5, 10, and 15 Hz. The mean squared prediction error (MSPE) resulting from nearest neighbor local linear prediction was taken as complexity index. Complexity maps were generated interpolating the MSPE index over a schematic scalp representation.


RESULTS
Statistical analysis revealed that: i) EEG shows good predictability in all conditions and seems to be well explained by a linear stochastic process; ii) the complexity is lower with EC than with EO and increases significantly during PS, to a lesser extent during 10 Hz stimulation; iii) significant differences of EEG complexity are detectable between anterior-central and posterior scalp regions.


CONCLUSIONS
Changes in EEG complexity during PS can be successfully assessed using nonlinear prediction. The observed modifications in the patterns of complexity seem to reflect neurophysiological behaviors and suggest future applicability of the method in clinical settings.
Erla
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Biophysics and Biosignals Lab., Dept. of Physics (Biotech), University of Trento, Via delle Regole 101, 38123 Mattarello, Trento, Italy. silvia.erla@unitn.it
Faes
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Nollo
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D000328:Adult; D000465:Algorithms; D001931:Brain Mapping; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D017711:Nonlinear Dynamics; D010775:Photic Stimulation; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted