Automation of the social interaction test by a video-tracking system: behavioural effects of repeated phencyclidine treatment.

The social interaction test is a valuable behavioural model for testing anxiolytic and neuroleptic drugs. The test quantifies the level of social behaviour between pairs of rats and it is usually based on manual analysis of behaviour. Advances in computer technology have made it possible to track the movements of pairs of rats in an arena, and the present paper describes the automation of the social interaction test by the commercial video-tracking programme, the EthoVision system. The ability of the automated system to correctly measure the social behaviour of rats is demonstrated by determining a dose-response relationship in the social interaction test for phencyclidine, a psychotomimetic drug that reduces social behaviour between pairs of rats. These data are subsequently analysed by the manual and automated data-acquisition methods and the results are compared. The study shows that the automated data-acquisition method best describes the behavioural effects of phencyclidine in the social interaction test by the locomotor activity of the rats, how much time the rats spend in different sections of the testing arena, and the level of social behaviour. Correlation analysis of the results from the manual and automated data-acquisition methods shows that the social behaviour measured by the automated system corresponds correctly to the social behaviour measured by the manual analysis. The present study has shown that the automated data-acquisition method can quantify locomotor activity, how rats use a testing arena and the level of social behaviour between rats in the social interaction test. The system cannot distinguish between social and aggressive behaviours, and therefore the rats should be tested in an unfamiliar arena to reduce territorial behaviour. Taking this limitation into consideration, the social interaction test can be automated by this computer-based video-tracking system and can be used as a routine test for quantifying the effects of drugs on the social behaviour of rats.