To understand the effects of cocaine on the cerebral cortex, 14 male polydrug abusers were enrolled in a study on the effects of cocaine on the electroencephalogram (EEG). The experimental treatments were placebo, 20 mg cocaine or 40 mg cocaine IV administered in a double blind, pseudorandom design. The EEG was recorded from 13 electrode positions over the left hemisphere during a 3-minute baseline recording and for 30 minutes after initiation of the IV injection. The spectral power for delta, theta, alpha and beta EEG bands was calculated KEY WORDS: Cocaine; EEG; Drug abuse Despite the epidemic of cocaine abuse during the past two decades, little is known about the neurophysiolog ical effects of this drug in humans. Berger, the frrst to study effects of cocaine on the human EEG, noted that 30 mg of subcutaneous cocaine increased EEG alpha abundance in two subjects (Berger 1931). Using an am plifter that allowed the recording of EEG in the beta fre quency range, he later observed an increase in EEG beta

Little is known about the effects of cocaine on cognitive tasks. Event-related potentials (ERP) were recorded in 7 cocaine abusers during the performance of the auditory oddball task before and after the intravenous injections of saline and cocaine (60–80 mg). The P3B and slow wave components of the ERP were significantly larger 60–210 min after the cocaine than after the placebo injection. The results suggest that cocaine abusers have difficulty in maintaining optimal stimulus processing during extended testing. Cocaine blocks this decrement in stimulus processing.

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