The Single-trial Extraction Of VEP And AEP Based Lifting Wavelets Transform Method

Because evoked potentials can reflect the relationship between brain functional status and nervous system pathological changes and damage, so usually through the evaluation of evoked potentials to evaluate the brain and nervous system. Usually evoked potentials were submerged in strong background noise, traditional comparative simple and easy extract methods are based multiple or less times superposition average, although can obtain certain effect, but it to lose large details for cos,so it is essential to extract evoked potentials by single-trial.This paper based on the data acquisition from "oddball" mode, the data contain visual evoked potentials (VEP) and auditory evoked potentials (AEP), and carry on the single extraction. Using traditional Mallat method and lifting wavelet transform method to single-trial extraction the VEPs which are simulated and have different signal-to-noise ratio (SNR), through the observation of the whole waveform and investigated denoising index, confirm that lifting wavelet transform method have more advantages. Use of improved threshold of lifting wavelet transform method for VEP single-trial extraction, and obtain good whole waveforms and feature point informations (latency, amplitude), results show that single extraction obtain more informations than superposition average. This paper also have AEP single-trial extraction, and achieved good results, it still confirm that single-trial extraction have more advantages than superposition average.