EFFECTS OF INFUSION OF CHOLINERGIC DRUGS INTO THE PREFRONTAL CORTEX AREA ON DELAYED MATCHING TO POSITION PERFORMANCE IN THE RAT

Rats trained on a Delayed Matching To Position (DMTP) task displayed m ediating behavior during delays to solve the task. Infusion of the cho linergic antagonist,scopolamine into the medial Prefrontal Cortex area (mPFC), dose dependently impaired performance independent of delay. T hese results indicate that scopolamine does not specifically affect wo rking memory. Infusion of the cholinesterase inhibitor physostigmine, muscarinic subtype receptor antagonists, the dopamine (D-1) antagonist SCH23390, and of the GABA-A receptor antagonist bicuculline, did not affect performance in the DMTP task, in a post-hoc analysis scopolamin e was found to impair discriminability in a delay-dependent manner onl y in animals that used mediating behavior in the majority of the trial s. Furthermore, a time sampling method indicated that scopolamine infu sions into the mPFC disrupted mediating behavior during the task. Resu lts suggest that cholinergic systems in the mPFC play a role in direct ing attention to task relevant behavior.