Long-lasting inhibitory avoidance acquisition in rats submitted to the elevated T-maze model of anxiety.

摘要

The present study was outlined in order to provide additional behavioral validation to the elevated T-maze as a model of anxiety and memory. In this model, rats acquire an inhibitory avoidance response after successive exposures, and memory can be estimated by retesting later. Two experiments were carried out with rats initially tested at the ages of 30, 60, 90 and 120 days. Experiment 1 showed that, while 100% of subjects studied learned inhibitory avoidance, regardless of their ages, 60-day-old rats needed a higher number of trials in order to reach the criterion to stay 300 s inside the enclosed arm. Experiment 2 explored the relevancy of the aversive stimulus in maintaining the learned experience by retesting the subjects monthly. The results showed that after acquisition of inhibitory avoidance there is remarkable long-lasting memory retrieval. Risk assessment behavior, increasing in the first trial of the retest day, revealed also the approach-avoidance conflict while on the enclosed arm. The results are discussed in terms of age effects and the implications of an enduring learned emotional response in animal models of anxiety and memory.