Impaired visuospatial divided attention in the spontaneously hypertensive rat

The spontaneously hypertensive rat (SHR) is a potential rodent model for the impulsive, inattentive and hyperactive aspects of attention deficit/hyperactivity disorder. Impaired response inhibition and deficits of visual attention are demonstrable phenotypes of SHR (compared with normotensive Wistar-Kyoto rats), and alterations of catecholaminergic transmission in the prefrontal cortex are thought to contribute to aspects of the phenotypic differences. Here, we investigated the attentional performance of SHR and WKY, using a lateralized reaction time task, a behavioral measure of visuospatial divided attention. SHR acquired the conditional rule of the task normally but exhibited deficient accurate performance when stimulus durations were ultimately decreased to less than 1 s. The alpha-2 agonist guanfacine, which is used clinically to treat symptoms of AD/HD, was without effect on the performance of either SHR or Wistar-Kyoto rats. These data indicate that SHR exhibit performance deficits on a test of visual attention but do not resolve the predictive validity this putative model for AD/HD.