Wavelet analysis of learning and forgetting of photostimulation rhythms for a nonstationary electroencephalogram

Abstract

Quantitative parameters characterizing transient processes of mastering and forgetting of photostimulation (PST) rhythms for a nonstationary electroencephalogram (EEG) are developed on the basis of a continuous wavelet transformation. Nonstationarity factor K _nst(μ), as well as rhythm mastering K _M (μ) and confinement K _C (μ) factors are calculated for various spectral ranges μ. Photoflash mastering time τ _M = τ _S + τ _I , which is the sum of latent silence period τ _S after PST actuation and the rhythm increasing period τ _I is calculated. In the case of PST, the EEG rhythm retardation time τ _R relative to the beginning of PST is calculated. Rhythm forgetting time τ _F = τ _P + τ _D after PST actuation is the sum of the preservation time τ _P of the corresponding rhythm over a certain time interval and its decay period τ _D . The lag time τ _L of the EEG signal relative to the PST signal after its removal is determined. The proposed method is used in quantitative analysis and classification of transient processes characterizing the properties of the central nervous system. Possible applications of the method in analysis of various nonstationary signals in physics are discussed.