SCOPOLAMINE-INDUCED DEFICITS IN A 2-TRIAL OBJECT RECOGNITION TASK IN MICE

THE purpose of the present study was to design an object recognition t ask in mice and characterize the effects of scopolamine in this paradi gm. This task consisted of exposing mice for 6 or 10 min to an object in an open field (trial 1) and, after a delay (1-24 h), testing mice f or 10 min with the object and a novel object (trial 2). Mice explored the novel object more than the familiar object as the inter-trial dela y decreased and/or the duration of trial 1 increased. Administration o f scopolamine (0.3, 1 and 3 mg kg(-1), s.c.) before trial 1 reduced re cognition performance on trial 2 after a 3 h inter-trial delay and ind uced other behavioural effects, including an increase in locomotor act ivity on trial 1. Methylscopolamine (1 mg kg(-1)) had no effect on rec ognition performance. The present results show that this task is a use ful model to test recognition memory in mice and that blocking the cen tral cholinergic system impairs this form of memory.