Assessment of CNS drug activity in rhesus monkeys by analysis of the EEG.

The data generated from the application of spectral analytical techniques to the analysis of electroencephalograms (EEG) provide a reliable base for the quantification of such data. Drugs with a wide range of central nervous system (CNS) activities were characterized by their effects on neocortical EEGs of Macaca mulatta monkeys according to the specificity of autospectral changes at different anatomical sites. Changes in total spectral power, in the shape of the spectral envelope, and in the relative stability of the drug-induced EEG were assessed at various doses. Electroencephalograms were recorded from epidural electrodes under resting conditions and under the influence of CNS drugs. Autospectra representing sequential 4-second samples of EEG were generated successively over a nominal frequency band of 0-64 Hz. Averages of sequential autospectra were computed over specified time periods. Spectral power over the entire bandwidth and selected frequency regions was calculated and compared. This facilitated the grouping of drugs with similar activities, as well as the distinguishing of changes not readily detectable by visual inspection of the conventional EEG in the time domain.