For the first 7–10 days rats were habituated to the experimenter. During this period, rats were handled frequently and introduced to new types of foods and flavored water which were later used as rewards in the experimental arena. The procedure was aimed to decrease stress and prevent neophobia towards rewards given during behavioral training. Rewards consisted of palatable 45 mg food tablets in six flavors: basic company flavor, banana, bacon, chocolate, peanut butter, and fruit punch (diet AIN-76A: RodTab45MG; RodTabBan45MG; RodTabBcn45MG; RodTabChoc45MG; RodTabPbtr45MG; RodTabFrtP45MG5TUL, TestDiet, Richmond, IN, USA). Rats received also 4 types of fluids: mineral water, 4% sucrose in mineral water, 0.1% saccharine in mineral water, and 1:1 mixture of 4% sucrose, and 0.1% saccharine solutions (sucrose and saccharin, Sigma-Aldrich, St. Louis, MO, USA).
In order to motivate animals to work for food, rats were food-restricted up to 85% of their ad libitum body weight. Rats were subjected also to mild water restriction before behavioral sessions (4–12h). Experiments were carried out 5 days a week. During the weekend, animals had free access to standard rodent food and unsweetened mineral water.
In order to motivate animals to work for food, rats were food-restricted up to 85% of their ad libitum body weight. Rats were subjected also to mild water restriction before behavioral sessions (4–12h). Experiments were carried out 5 days a week. During the weekend, animals had free access to standard rodent food and unsweetened mineral water.