Behavioural Brain Research 286 (2015) 80–84 Contents lists available at ScienceDirect Behavioural Brain Research jou rn al hom epage: www.elsevier.com/locate/bbr Short Communication Time decay of object, place and temporal order memory in a paradigm assessing simultaneously episodic-like memory components in mice Hassina Belblidia a,b , Abdelmalek Abdelouadoud b , Christelle Jozet-Alves a , Hélène Dumas a , Thomas Freret a , Marianne Leger a , Pascale Schumann-Bard a,∗ a Normandie Universités, Université de Caen Basse-Normandie, Groupe Mémoire et Plasticité comportementale (GMPc), EA 4259, F-14032 Caen, France b Université des Sciences et de la Technologie Houari Boumediene, Laboratoire de Neurosciences Comportementales et Cognitives, 16111 Alger, Algeria h i g h l i g h t s • Mice successfully performed the three-trial object recognition task up to 2 h ITI. • The different components of episodic-like memory display a similar time course decay. • This paradigm may provide a usefulness tool for the screening of promnesic drugs. a r t i c l e i n f o Article history: Received 15 December 2014 Received in revised form 15 February 2015 Accepted 20 February 2015 Available online 28 February 2015 Keywords: Episodic-like memory NMRI mice Object recognition a b s t r a c t A common trait of numerous memory disorders is the impairment of episodic memory. Episodic memory is a delay-dependant memory, especially associating three components, the “what”, “where” and “when” of a unique event. To investigate underlying mechanisms of such memory, several tests, mainly based on object exploration behaviour, have been set up in rodents. Recently, a three-trial object recognition task has been proposed to evaluate simultaneously the different components of episodic-like memory in rodents. However, to date, the time course of each memory component in this paradigm is not known. We characterised here the time course of memory decay in adult mice during the three-trial object recognition task, with inter-trial interval (ITI) ranging from 1 h to 4 h. We found that, with 1 h and 2 h, but not 4 h ITI, mice spent more time to explore the displaced “old object” relative to the displaced “recent object”, reflecting memory for “what and when”. Concomitantly, animals exhibited more exploration time for the displaced “old object” relative to the stationary “old object”, reflecting memory for “what and where”. These results provide strong evidence that mice establish an integrated memory for unique experience consisting of the “what”, “where” and “when” that can persist until 2 h ITI. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Episodic memory is one form of declarative memory that is early impaired in Alzheimer disease [1]. It is defined as the ability of recollecting the three components of a unique personal experi- ence: “what” happened, “where” and “when” it occurred [2–4]. It also requires autonoetic consciousness (i.e. conscious experience Abbreviations: ELM, episodic-like memory; ITI, inter-trial interval; Os , stationary old object; O d , displaced old object; Rs , stationary recent object; R d , displaced recent object. ∗ Corresponding author at: Université de Caen Basse-Normandie, Groupe Mémoire et Plasticité comportementale (GMPc), EA 4259, Campus Santé, Bd Henri Becquerel, F-CS 14032 Caen, Cedex 5, France. Tel: +33 2 31 56 68 75. E-mail address: pascale.schumann-bard@unicaen.fr (P. Schumann-Bard). of recollection) and involves mental time travel. As non-linguistic behavioural markers of autonoetics consciousness are missing, it is difficult to bring evidence of such capacity in non-human animals. To solve this issue, behavioural paradigms were described to test this memory in animal models, which is referred to as episodic-like memory (ELM, [5]) and based on the “what”, “where” and “when” content of a unique episode. Clayton and Dickinson were the first to demonstrate ELM in animals. Indeed, they have shown that food- caching scrub jays are able to remember what kind of food was hidden, its location, and for how long they have stored it [5]. Oth- erwise, such a kind of memory has thereafter been reported in different animals species, for instance in meadow voles [6], great apes [7] and very recently in an invertebrate animal species, the common cuttlefish [8]. As rodents are the most used laboratory animals, several pro- cedures have been described in those species. In rats, Babb and http://dx.doi.org/10.1016/j.bbr.2015.02.043 0166-4328/© 2015 Elsevier B.V. All rights reserved.