Scalp topography of photic evoked potentials. Application of wave form decomposition technique.

A new method of wave form decomposition by using an evoked potential model was applied to the study of scalp topography of photic evoked potentials in 3 normal subjects. The parameters of the evoked potential model were composed of gain, natural frequency, damping ratio and time lag, and were determined in the frequency domain to minimize the square sums of the modeling error. By using the optimal model parameters, the wave form was decomposed into basic components. At least 4 components occurring within the initial 200 msec period after the stimulus onset were identified in all subjects and were shown to have different scalp distributions, suggesting different generator sources.