The qEEG parameters such as power spectrum and band powers are mostly used in evaluation of drug effects. Particularly, it has been tried to develop methods for screening clinical effect of centrally acting drugs.ĭrug-induced EEG changes have been used as an indicator of drug action. Quantitative electroencephalography (qEEG) has been applied to the various purposes: to characterize psychotropic drug effects in human and animals ( Herrmann, 1982), to develop sensitive biomarkers for diagnosing psychiatric disorders ( John et al., 2007 Leiser et al., in press), disease progression ( Luckhaus et al., 2008), treatment prognosis ( Hansen et al., 2003), and to predict clinical efficacy of putative psychoactive substances ( Knott et al., 1996 Parker et al., 2001 Galderisi, 2002). Then, the combination of power spectral analysis and statistical analysis may help to classify actions of centrally acting drugs. Because the distance between two locations in the canonical space (Mahalanobis distance) indicates the magnitude of difference between two different sets of EEG parameters statistically, the canonical scores and the distance may be used to quantitatively and qualitatively describe the dose-dependent and time-dependent effects and also tell similarity and dissimilarity among effects. While changes of the band powers produced by physostigmine and yohimbine were too redundant to describe the difference between two drugs, locations of two drugs in the reference canonical space represented the difference between two drug's effects on EEG. Eight relative band powers of EEG produced by either physostigmine or yohimbine were reduced to two canonical scores in the reference canonical space. We calculated factor loadings from normalized values of eight relative band powers (powers of 0.5, 1.0~2.0, 2.5~4.0, 4.5~5.5, 6.0~8.0, 8.5~12.0, 12.5~24.5, and 25~49.5 Hz bands expressed as ratios of the power of 0.5-49.5 Hz band) of EEG during pre-drug periods (11:00~12:00) by factor analysis and constructed a two-dimensional canonical space (reference canonical space) by canonical correlation analysis. It is desirable to reduce multiple EEG parameters to a few components that can be manageable in a real space as well as be considered as parameters representing drug effects.
Although quantitative EEG parameters, such as spectral band powers, are sensitive to centrally acting drugs in dose- and time-related manners, changes of the EEG parameters are redundant.
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