Functional connectivity during eyes-closed EEG was different between light and heavy drinkers in a study on EEG synchronization in heavy-drinking college students, defined as those who consume more than 30 units containing 12 grams of alcohol per week (de Bruin et al., 2004). Heavy drinkers exhibited abnormally increased synchronization in theta (4–8 Hz) and gamma (30–45 Hz) bands. These frequency bands have been associated with memory formation involving hippocampo-neocortical connections (Buzsaki, 1996). Altered synchronization could reflect structural changes in neural networks involving the hippocampus and cortex, as observed in pathological studies (Harper, 2009). EEG synchronization in six frequency bands (delta, theta, alpha, slow beta, fast beta, and gamma) when compared between low, moderate, and heavy drinkers revealed a loss of lateralization in alpha and slow beta bands in male and female heavy drinkers (de Bruin et al., 2006). In addition, moderately and heavily drinking males had lower fast beta (20–30 Hz) synchronization than light-drinking males; synchronization in alpha and beta frequencies was impaired during rest and mental rehearsal in those drinking in excess of 21 alcoholic drinks per week.
