Classification of psychotropic drugs by rat EEG analysis: the anxiolytic profile in comparison to the antidepressant and neuroleptic profile.

Electroencephalograms were recorded from the parietal and frontal cortex of freely moving rats held in constant vigilance by placing them in a slowly turning drum. The effects of 5 clinically effective anxiolytics, buspirone, meprobamate, phenobarbital, chlordiazepoxide and diazepam, were studied after intraperitoneal injection of different doses. After on-line fast Fourier transformation of the EEG signal, the drug effects were quantified by an Analysis of Variance. This resulted in a t profile for each drug dosage. Averaging the t profiles of all dosages of a drug results in a 'drug profile'. Averaging the drug profiles of the 5 anxiolytic drugs tested results in an 'anxiolytic profile'. This profile is characterized by a power decrease from 8 to 11 Hz and above 70 Hz and a power increase from 20 to 60 Hz. The anxiolytic profile is compared with the formerly defined antidepressant and neuroleptic profiles and can be clearly distinguished from the latter two.