Wavelet spectra of visual evoked potentials: Time course of delta, theta, alpha and beta bands

We study spectral energy transformations in the electroencephalogram associated with visual evoked potentials initiated by red, green and yellow light flashes. With the aid of a complex continuous wavelet transform we show spectral energy changes to occur non-monotonically in delta, theta, alpha and beta bands. Each band has inherent energy flow patterns for 1s after stimulation. Energy flows in alpha and beta bands are alike and differ from those in theta and delta bands. Beta band power and energy flows are small.