Subjects subsequently participated in both alcohol and placebo MEG sessions in a counterbalanced manner. The within-subject design minimized influence of individual differences in anatomy, alcohol metabolism, and brain activation patterns, resulting in reduced error variance and increased statistical power. Placebo and alcohol sessions were 32±26 days apart on average. Urine pregnancy test administered to women in the beginning of each session ascertained that none were pregnant. All subjects were asked about their compliance with requirement to abstain from food for 3 hours and from alcohol at least 48 hours prior to each experimental session. Breath alcohol concentration (BrAC) was measured with a breathalyzer (Draeger, Inc.) upon arrival and throughout the session when the subjects were outside the recording chamber. Since no electronic device can be used in the magnetically shielded room, BrAC was estimated with Q.E.D. Saliva Alcohol Test (OraSure Techn, Inc.) during the recording. The subjects rated their momentary moods and feelings with the Biphasic Alcohol Effects Scale, BAES [72] prior to drinking (at baseline), on the ascending BrAC and descending BrAC limbs. The mood ratings were obtained for
