If mice are offered a single bottle of a high concentration of alcohol (20%) for 2–4 h starting soon after the onset of their circadian dark cycle, some will drink a great deal of alcohol and achieve measurable BECs (Rhodes et al. 2005). Strains differ markedly in DID, with C57BL/6J drinking the most and DBA/2J among the least; the trait is heritable, as inbred strains differ markedly in their BECs after a DID test (Rhodes et al. 2007). The DID phenotype, and the selected lines developed based upon high BECs during this test (see next section), are not intended as an animal model of alcoholism. Rather, we have targeted a single deficiency of the older models, i.e., the failure to show a pattern of binge-like drinking that leads to intoxication. A principal limitation of the phenotype is that during the DID test, no choice is offered—the animals, for a 2 or 4 h period, have only access to ethanol. While they do not have to drink in order to maintain a normal physiological state [i.e., they are not fluid-deprived (Toth
