Previous maze experience required to increase open arms avoidance in rats submitted to the elevated plus-maze model of anxiety

Abstract

Studies have shown an increased open arm avoidance in rats re-exposed to the elevated plus-maze (EPM), which suggests a qualitative shift in emotional states from an unconditioned (Trial 1) to a learned (Trial 2) form of fear response, but a precise source of aversion has not been determined. Using rats submitted to the EPM or various EPM-derived configurations, this study was designed to investigate what previous maze experiences in Trial 1 are required to increase avoidance of open arms in EPM Trial 2. Results obtained from rats submitted to the EPM or EPM-derived configurations confirmed the increased open arms avoidance in Trial 2. Rats confined to either open or enclosed arms failed to show the increased avoidance of open arms in Trial 2. The results are discussed in terms of the minimum prerequisite in Trial 1 to elicit an avoidance learning response to open arms in Trial 2, and also the implications of an acquired fear response in rats for the study of the biological basis of anxiety.