Shannon_2004_Eur.J.Pharmacol_498_125

Higher levels of cognition, such as executive functions, are known to be disrupted in psychiatric disorders such as schizophrenia. As a potential model of executive function, rats were trained in a three-lever operant conditioning chamber to respond on two of the three levers in one of six possible correct sequences. When the rat completed a two-response sequence correctly for 10 consecutive trials, the correct sequence was randomly changed to another two-response sequence without signaling the rat. Rats readily acquired the behavioral baseline and completed all six response-sequences within a 60-min session. Phencyclidine, MK-801 ((5S,10R)-(+)-5-Methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine), apomorphine, scopolamine and triazolam all produced dose-related decreases in the total number of sequences completed. Phencyclidine and MK-801 markedly increased all errors while scopolamine produced modest increases; triazolam increased only total and intrarule errors, while apomorphine had no significant effect on errors. The present results suggest that within-session repeated acquisition of response sequences has the potential to be a useful model for studying executive function in rats.