POWER SPECTRAL-ANALYSIS OF ELECTROENCEPHALOGRAPHIC DESYNCHRONIZATION INDUCED BY COCAINE IN THE RAT

Whereas it is well-known that cocaine induces EEG desynchronization an d behavioral excitation in animals and human subjects, the detailed ef fect of cocaine on EEG activity remains to be fully elucidated. This c ommunication reports our attempts in quantifying the effect of cocaine on EEG signals recorded from the somatosensory cortex of adult male S prague-Dawley rats under chloral hydrate anesthesia (400 mg/kg i.p.). Continuous, on-line and real-time power spectral analysis revealed tha t i.v. administration of two doses of cocaine (1.5 or 3.0 mg/kg) dose- dependently induced EEG desynchronization, as indicated by a decrease in the root mean square and an increase in the mean power frequency va lues. More interestingly, whereas both doses of cocaine promoted a red uction in the alpha (8-13 Hz), Theta (4-8 Hz) and delta (1-4 Hz) spect ral components, the beta band (13-32 Hz) underwent differential altera tions. The lower dose of cocaine elicited a transient increase, follow ed by a decrease in the power of the beta band. A prolonged increase i n the power of the beta band, on the other hand, was observed after th e higher dose of cocaine. These results suggest that subtle changes in the individual EEG spectral components, which are dose-dependent, may underlie the EEG desynchronization induced by cocaine.