Standardization vs. normalization in the power spectral analysis of the EEG signal.

Data from power analysis of the human EEG were processed statistically, and an area within the power spectrum was identified, limited by the abscissa and by an exponential curve, the parameters of which could be defined by a moving linear regression after logarithmic transform of the spectral data. The EEG signal of normal subjects and epileptics with borderline EEG tracings was studied before and after administration of neuroactive compounds. The exponential curve was found to be negative in all subjects; its parameters were symmetrical and were not modified by the drugs administered, though these were active on the spectral profile. The area limited by the curve was used as a reference for the standardization of the power values with respect to a constant to the signal. The method allowed a better definition of the spectral profile than it is obtained by normalization vs. the total power value.