Electroencephalographic correlates of marihuana-induced euphoria.

The present study was conducted to determine if there is a neurophysiological correlate of marihuana-induced good effects or euphoria. Three groups of 6 male occasional marihuana smokers were prepared for electroencephalographic (EEG) recording and smoked either placebo or marihuana cigarettes containing 1.26% or 2.53% delta 9-tetrahydrocannabinol (delta 9-THC) in a controlled laboratory setting. Using a continuously available non-verbal joystick device and a questionnaire, subjects reported changes in their subjective mood state while EEG activity was continuously recorded. Subjects reported multiple episodes of intense good effects or euphoria during the first 15 min after marihuana. These episodes of euphoria occurred while plasma delta 9-THC levels were rapidly rising. EEG alpha power during these discrete episodes of euphoria was significantly higher suggesting that these transient EEG changes may reflect a neurophysiological correlate of the reinforcing effects of marihuana.