Quantitative Analysis of the EEG - General Concepts and Animal Studies

Quantification of the EEG using digital computers is based on complex subjective processes of data reduction and feature extraction. In this paper, the signal characteristics of the EEG are identifred and major developments in the field of computerized electroencephalography (such as spectral analysis, compressed spectral arrays, etc.) are surveyed. Particular attention is given to signal analysis techniques used to characterize 1) background (stationary) EEG activity, and 2) interrelated multichannel EEG activity. The fast Fourier transform (FFT) has dominated approaches used to study background activity while cross-spectrum and coherence analysis have extended frequency or spectrum analysis into frequency-limited relationships between channels. In the realm of applications, the use of the digital computer-analyzed EEG to quantify 1) vigilance state dependent EEG changes, 2) the central effect of pharmacological agents, and 3) the normal ontogeny of the cortical and hippocampal EEG is described.