Research report Differential learning strategies in spatial and nonspatial versions of the Morris water maze in the C57BL/6J inbred mouse strain Amy Jo Stavnezer a,1 , Lynn A. Hyde a,2 , Heather A. Bimonte a,3 , Cary M. Armstrong a , Victor H. Denenberg a,b, * a Biobehavioral Sciences Graduate Degree Program, U-154, University of Connecticut, 3107 Horsebarn Hill Road, Storrs, CT 06269-4154, USA b Department of Psychology, University of Connecticut, Storrs, CT 06269, USA Received 2 July 2001; received in revised form 2 January 2002; accepted 2 January 2002 Abstract We recently developed a new nonspatial version of the Morris water maze that requires the use of four visually distinct intra-maze patterns to efficiently locate a hidden platform. The nonspatial version was designed to match the spatial version on complexity of cue usage, and differs only on spatiality of cues, thereby allowing more meaningful comparisons between the two versions. Following a previous experiment that demonstrated nonspatial learning with the BXSB inbred mouse strain, C57 inbred mice were tested in this study. They received spatial and nonspatial training in a counter-balanced order so that Test Order and information transfer could be assessed. Subjects that received spatial training first had superior performance in both the spatial and the nonspatial tasks when compared to mice that received nonspatial training first. The mice that received spatial training first used extra-maze cues as a spatial strategy. However, during nonspatial testing they did not use the intra-maze cues to locate the platform; instead, the mice used an egocentric strategy of circling through the platform annulus. Subjects that received spatial testing first were superior on the nonspatial task to those subjects that received nonspatial training first. Moreover, subjects that received nonspatial testing first were unable to learn the spatial version. Overall, C57 mice can learn both the spatial and nonspatial versions of the Morris maze presented here; however, the nonspatial version is more difficult and is solved using an egocentric strategy. # 2002 Elsevier Science B.V. All rights reserved. Keywords: C57BL/6J mice; BXSB mice; Learning; Transfer of training; Allocentric; Intra-maze cues; Extra-maze cues 1. Introduction The Morris maze can be used to study spatial and nonspatial learning in both rats and mice. In the spatial version, the subject is required to locate a submerged platform in a pool of water from various start locations, using stable extra-maze cues. The most widely used nonspatial Morris maze is the visible platform, a much easier task to solve than the hidden platform spatial version [13,15]. This task requires the use of only one intra-maze visible cue. Other nonspatial versions con- tain two visibly distinct platforms, have various stimuli attached to the platforms, or present a visible cue along the interior surface of the maze [10,11,14,17,18]. These versions, however, still differ from the spatial version in complexity (some are much easier than a hidden plat- form version and some are too difficult to learn), they often add tactile cues, and in general have a fewer number of cues that need to be integrated than the spatial version. Therefore, a direct comparison between these mazes and the hidden platform version is con- founded by factors other than cue usage. In an attempt to rectify this situation, we developed a nonspatial version of the Morris maze which makes extra-maze cues irrelevant and requires the use of complex intra-maze visual patterns to locate a hidden platform [22]. No tactile cues were placed inside the * Corresponding author. Tel.: 1-860-486-3826; fax: 1-860-486- 3827 E-mail address: dberg@uconnvm.uconn.edu (V.H. Denenberg). 1 Present address: Department of Psychology, Skidmore College, Saratoga Springs, NY 12866, USA. 2 Present address: CNS/CV Biological Research Department, Schering-Plough Research Institute, Kenilworth, NJ 07033, USA. 3 Present address: Departments of Physiology and Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA. Behavioural Brain Research 133 (2002) 261 /270 www.elsevier.com/locate/bbr 0166-4328/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0166-4328(02)00021-9