Spatial learning, contextual fear conditioning and conditioned emotional response in Fmr1 knockout mice

Fmr1 knockout mice are an animal model for fragile X syndrome, the most com mon form of heritable mental retardation in humans. Fmr1 knockout mice exhi bit macro-orchidism and cognitive and behavioural deficits reminiscent of t he human phenotype. In the present study additional behavioural and cogniti ve testing was performed. Knockouts and control littermates were subjected to a spatial learning test using a plus-shaped water maze. Animals had to l earn the position of a hidden escape platform during training trials. The p osition of this platform was changed during subsequent reversal trials. Pre viously reported deficits in reversal learning were replicated, but we also observed significant differences during the acquisition trials. A plus-sha ped water maze experiment with daily changing platform positions failed to provide clear evidence for a working memory impairment, putatively underlyi ng the spatial learning deficits. Two different test settings were used to examine the reported deficit of Fmr1 knockout mice in fear conditioning. Co nditioned fear responses were observed in a contextual fear test, and the a bility to acquire an emotional response was tested by means of response sup pression in a conditioned emotional response procedure. Neither protocol re vealed significant differences between controls and knockouts. (C) 2000 Els evier Science B.V. All rights reserved.