Time-frequency analysis of single-sweep event-related potentials by means of fast wavelet transform

A time-frequency decomposition was applied to the event-related potentials (ERPs) elicited in an auditory oddball condition to assess differences in c ognitive information processing. Analysis in the time domain has revealed t hat cognitive processes are reflected by various ERP components such as N1, P2, N2, P300, and late positive complex. However, the heterogeneous nature of these components has been strongly emphasized due to simultaneously occ urring processes. The wavelet transform (WT), which decomposes the signal o nto the time-frequency plane, allows the time-dependent and frequency-relat ed information in ERPs to be captured and precisely measured. A four-octave quadratic B-spline wavelet transform was applied to single-sweep ERPs reco rded in an auditory oddball paradigm. Frequency components in delta, theta, and alpha ranges reflected specific aspects of cognitive information proce ssing. Furthermore, the temporal position of these components was related t o specific cognitive processes. (C) 1999 Academic Press.