Cognitive effects of psychotomimetic drugs in rats discriminating number cues.
Psychopharmacology November 1, 2009 C B Willmore, D M Krall, F M Spears et al.
Deficits in memory and attention are known in psychosis, but experiments often test working memory without systematically varying attentional demands. This study used rats trained on operant ratio discrimination tasks to determine whether attention or memory contributes more to drug-induced performance deficits. Four psychotomimetic drugs—a serotonin agonist, the NMDA antagonist PCP, and two cannabinoid agonists—were assessed. A signal detection analysis dissociated cognitive from noncognitive disruptions. At least one dose of each drug decreased accuracy without affecting response rates, and task difficulty determined the specificity of accuracy effects. PCP and one cannabinoid biased animals toward the lever associated with denser reinforcement and produced peculiar response patterns during distracter light sessions, suggesting performance enhancement. Overall, sustained attention and transient information management were significantly impaired, while selective attention was less affected.