Estimation for Spread Forms of Spindle Waves in Multichannel EEG

Abstract

AbstractThe spindle wave is one of the most important EEG signals in exploring the mechanism of sleep. There have been few reports, however, that examined the spatial properties of the spindle wave. One reason for this may be that the spindle wave is difficult to be handled as a stationary time series since it is a short‐term signal. Another reason is that a multidimensional signal processing technique has not been established for the multichannel signal, and an analysis with a tremendous amount of data has not been tried.This paper aims at the analysis of the empirical knowledge of doctors by computer processing, and proposes an algorithm which estimates the spread form of the spindle wave in the multichannel EEG. The method is based on the frequency‐wavenumber spectrum, and has features in that the two phasic dominants and the direction of spread are estimated from a smaller number of measurements, by utilizing the phase relations on the scope.The usefulness of the proposed algorithm was verified by a computer simulation. The proposed estimation method was applied to the actual spindle waves, and the following result was obtained. The phasic dominant of the spindle exists around the central field for the low‐frequency components and around the parietal field for high‐frequency components. This is a quantitative result, which agrees with the traditional qualitative findings. A new observation was also made where the spindles spread mostly from the parietal field to the frontal field.