Effects of chlordiazepoxide and sodium valproate in two tests of spatial behaviour

The effects of chlordiazepoxide (CDP) and sodium valproate (VPA) were studied in rats trained to asymptotic performance on two tests of spatial behaviour, the 8-arm radial maze and the 8-choice arena. The task in the 8-arm maze was to locate a single food pellet at the end of each arm. Both CDP and VPA caused an increase in errors, an increase in performance time, and the utilization of a non-spatial response strategy. The task in the 8-choice arena was to locate a single water bottle from an octagonal array of eight otherwise empty bottles. For one group the goal bottle remained in the same place from trial to trial; for a second group the position of the goal bottle was cued by a black card over the nozzle; for the third group the goal bottle was uncued and moved randomly from trial to trial. VPA had no effect on performance, but CDP impaired performance in all three groups. These patterns of effects suggest that VPA may specifically disrupt working memory, but that the impairment of spatial performance by CDP probably results from a non-specific perceptual or attentional deficit.