Automation of the free-exploratory paradigm

Abstract

The free-exploratory paradigm (FEP) is currently the only proposed animal model of trait anxiety, making it highly valuable to behavioural neuroscience. However, FEP has not yet been automated, so its results depend on human scoring, which can be quite imprecise. The aim of this study was, therefore, to validate an automated version of FEP, using a commercially available video-tracking system (ANY-maze© – Stoelting Co., USA). To achieve this, two experiments were performed. The first one evaluated the reliability of the video-based automation of FEP, and the second, assessed whether the zeolites, used as a bedding material in the first experiment to facilitate video-tracking, influenced the animals’ behaviour in FEP. In experiment I, 15 drug-naive, adult, male rats were tested in FEP, while their behaviour was simultaneously evaluated by ANY-maze© and two human observers. Subsequently, the intraclass correlation coefficient (ICC) was calculated for the automated and manual results of the parameters “percentage of time in the novel side” (%TNS) and “total units visited” (TUV). The analysis resulted in high, significant values of ICC (%TNS: 0.9962 and TUV: 0.9453). In experiment II, 18 drug-naive, adult, male rats were allocated to two different groups: (1) tested in FEP with zeolites; and (2) tested in FEP with sawdust. The data obtained were analysed using the Student's t-test, which revealed no significant differences between the groups for the parameters %TNS and TUV. In conclusion, the data presented here show that automation of FEP, using a video-based tracking system, is not only possible, but also highly reliable.