In order for genetic studies using the endophenotype approach to be successful, it is extremely important to select well characterized (endo) phenotypes that meet the criteria of Gottesman and Gould [43]. Neuroelectric phenotypes (brain oscillations, such as EEG and those EROs underlying ERPs, including the P3 component) meet these criteria for endophenotypes for alcoholism, as they are heritable, and characterize not only those who are affected, but also offspring at risk [42]. The data on the heritability of EEG frequencies are quite compelling. High concordance rates in the spectral characteristics of resting eyes-closed EEG have been reported from monozygotic twin pairs compared to dizygotic twin pairs. A large twin study indicates that power in all frequency bands of the resting EEG is highly heritable: delta 76%, theta 89%, alpha 89%, and beta 86% [57,58]. The power estimates of frequency bands may be more heritable than ERP components giving them a slight edge as endophenotypes [178]. As reviewed in the previous sections, event-related oscillations (EROs) meet the criteria of endophenotypes for alcoholism, as reduced delta, theta and gamma oscillations not only
