Impaired spatial processing in a mouse model of fragile X syndrome.

Abstract

Fragile X syndrome (FXS) is the most common form of inherited intellectual impairment. The Fmr1mouse model has been previously shown to have deficits in context discrimination tasks but not in the elevated plus-maze. To further characterize this FXS mouse model and determine whether hippocampal-mediated behaviours are affected in these mice, dentate gyrus (DG)-dependent spatial processing and Cornu ammonis 1 (CA1)-dependent temporal order discrimination tasks were evaluated. In agreement with previous findings of long-term potentiation deficits in the DG of this transgenic model of FXS, the results reported here demonstrate that Fmr1mice perform poorly in the DG-dependent metric change spatial processing task. However, Fmr1mice did not present deficits in the CA1-dependent temporal order discrimination task, and were able to remember the order in which objects were presented to them to the same extent as their wild-type littermate controls. These data suggest that the previously reported subregional-specific differences in hippocampal synaptic plasticity observed in the Fmr1mouse model may manifest as selective behavioural deficits in hippocampal-dependent tasks.