EEG alpha activity increases during transient episodes of ethanol-induced euphoria

The effects of acute ethanol administration were studied in 18 men to determine the electroencephalographic (EEG) correlates of ethanol-induced behavioral changes. Subjects were instructed to operate an instrumental device to indicate changes in their subjective mood state while EEG activity and plasma ethanol levels were continuously measured. Three groups of 6 subjects consumed either placebo, 0.347 g/kg ethanol or 0.695 g/kg ethanol over a 15 min period. EEG and behavioral changes were directly correlated with plasma ethanol levels during the ascending limb of the plasma ethanol curve. Theta EEG activity increased proportionally as plasma ethanol levels increased during the 2 hr recording session. Alpha EEG activity increased during the first hour and then returned to control levels. The increased alpha activity was most prominent when subjects reported feeling intense pleasure or euphoria. Power spectral analysis of discrete samples of EEG activity revealed that transient increases in alpha activity paralleled the onset of ethanol-induced euphoria. These data suggest that ethanol-induced behavioral effects are associated with discrete changes in brain electrical activity.