Testing for Synchronization in Evoked Potentials Using Higher Order Spectra Technique

Abstract

Ensemble averaging is commonly employed to estimate brain activity evoked by known stimulus. Similar distorted average responses will be obtained whether there is a partial blocking of the nerve, or synchronization disorders. Two algorithms for detecting the responses and the amount of synchronization, which are insensitive to asynchronization problems, are introduced. The first is based on estimating the spectrum of the recorded evoked response, and the other on estimating its bispectrum. In the spectral method, the background noise spectrum should be known or estimated. In the bispectral method, no additional estimation is required, if the signal has a zero dc-component, and the background noise is zero-mean and white, of any symmetric distribution.