Assessment of Exploratory Activity and Anxiety in Rats with Different Levels of Impulsive Behavior

Selection of a pedal to obtain reinforcement depending on its value and delay time was used to divide rats into three groups. Animals selecting the valuable but delayed reinforcement in more than 70% of cases were assigned to the self-controlled groups, while those making this choice in fewer than 30% of case were assigned to the impulsive group and rats showing no preference in choosing reinforcement were members of the ambivalent group. The levels of orientational-exploratory activity and anxiety in rats with different types of behavior were then assessed in an elevated plus maze, on acquisition of a conditioned fear reaction (fear conditioning), and in a neophagophobia test (novelty suppressed feeding). The animals which were least active and most anxious in all tests were those of the self-controlled group. Ambivalent rats were the least anxious in the elevated plus maze test and produced the greatest number of successful trials in terms of finding and eating food in the novel context, as compared with rats of the other groups. Impulsive animals demonstrated more marked freezing reactions on acquisition of the conditioned fear reaction in the fear conditioning test and found food more quickly in the novel context.