Following eight weeks of two-bottle choice exposure, animals were switched to an operant setting to investigate whether prior long-term ethanol exposure would lead to the initiation of operant responding for either 20% or 10% ethanol, respectively, without the use of sucrose fading. Sessions occurred five days per week (Monday–Friday) regardless of their previous two-bottle-choice regimen. Food and water were available ad libitum at all times in the home cage throughout the training. For the first two days of training animals were placed in the operant conditioning chambers for a 14-h overnight session on an FR1 schedule of reinforcement (0.1 ml after a single active lever press) with 20% or 10% ethanol solution as the reinforcer. Once the active lever is pressed, the stimulus light above the lever was illuminated for 3 seconds and was accompanied by a 3 second tone to indicate availability of the reinforcer in the dipper receptacle. The dipper port was illuminated for 10 seconds whilst the dipper cup was available. If the cup was not actively licked during the 10 seconds, the cup fell and this
