AN ANALYSIS OF INTERCORRELATIONS AMONG SPECTRAL AMPLITUDES IN EEG - A GENERATOR STUDY

The objective of this study is to explore the physiological sources of covariation between multiple narrow-band EEG spectral amplitudes with an aim toward parsimonious modeling of the observed intercorrelations. Specifically, a factor-analytic model describing the intercorrelations among 25 spectral amplitudes, at 1-Hz increments from 1 to 25 Hz, is presented. This method is applied to the EEGs obtained from a group of five subjects controlled for age, sex, state of consciousness, and recording dipole. The subjects were studied in waking and sleeping states in order to examine how this model would represent such physiological changes. It is concluded that only four factors are necessary to account for all the variability in either condition, and that only two factors per state of consciousness are of great importance. Constant and state-of-consciousness specific features of the factors are discussed. It is hypothesized that the frequencies significantly loaded within a given factor are related because of their correlation to a common hypothetical generator. Some implications for broad-band EEG analysis are discussed. Copyright © 1969 by The Institute of Electrical and Electronics Engineers, Inc.