For experiments using voluntary ethanol intake, subjects were acclimated to ethanol gradually, using a variant of the two-bottle choice paradigm (Martinetti et al., 2000). Animals were exposed to unsweetened ethanol in plastic bottles for 12 h each day, starting 4 h into the dark cycle. Unless otherwise stated, every four days, the concentration of ethanol was increased in the following manner: 1%, 2%, 4%, 7% and, in some cases, 9% (v/v).
