The working memory capabilities of the spontaneously hypertensive rat

This study addresses the working memory capabilities of the male spontaneously hypertensive rat (SHR) strain as compared to the normotensive inbred strain, Wistar Kyoto (WKY), and the out bred Sprague Dawley (SD) rat as a normal control. The objective was to use two working memory tasks in the water maze with different strategic demands: forced alternation (FA) which allows the use of either an allocentric ("place") or egocentric ("response") localisation strategy and delayed matching-to-place (DMP) which requires an allocentric strategy. In the FA task, SHR reached criterion at the same rate as WKY and SD controls and were impaired to the same extent as WKY at the long (1 h) delay. Furthermore, both SHR and WKY were impaired relative to SD when the memory load was increased through the use of massed trials. In the DMP task, the performance of SHR did not differ from that of either of the control strains, either during training or in response to delay. These findings do not provide evidence of short-term memory impairments in the SHR, which is a commonly-used animal model of Attention Deficit Hyperactivity Disorder (ADHD) in humans.