All mice were maintained in a temperature-controlled colony room (21–23°C) on a 12-h light–dark cycle and were allowed free access to food and water. Details concerning the formation of the HS4 colony are found elsewhere (Malmanger et al. 2006). Briefly, the colony is maintained as 48 families; the standard circle design is used for breeding. G19 animals were used as the founding population for STSB. Three to four males and females from each of 48 families were used for selection; details of the selection phenotypes (acute ethanol withdrawal and ethanol consumption) follow. The HS4 animals were divided into two cohorts of approximately equal size; one cohort was used to select for ethanol withdrawal, and the other was used to select for ethanol consumption. However, all animals were phenotyped for both traits, with ethanol consumption always preceding acute withdrawal. The order of testing is important; in the B6, D2, and C inbred strains, testing first for ethanol consumption does not affect the withdrawal response. However, the reverse is not true; ethanol consumption is significantly decreased in the B6 and C strains after exposure to acute withdrawal (unpublished observations).
