EFFECTS OF CHOLINERGIC DRUG INFUSIONS INTO THE DORSAL PART OF THE MEDIAL PREFRONTAL CORTEX ON DELAYED CONDITIONAL DISCRIMINATION PERFORMANCE IN THE RAT

Effects of bilateral infusions of cholinergic drugs into the dorsal pa rt of the medial prefrontal cortex (dmPFC) on performance in a delayed conditional discrimination (DCD) task were examined in rats. Scopolam ine dose-dependently impaired performance. No delay-dependent effect w as found indicating that scopolamine did not specifically affect worki ng memory (WM). Physostigmine alone induced a slight improvement of DC D performance independent of delay and co-administration of physostigm ine with scopolamine attenuated the scopolamine-induced impairment of DCD performance. Infusion of the muscarinic M(2) antagonist AQRA-471, the M(3) antagonist 4-DAMP and the mixed M(1)-M(3) antagonist UH-AH 37 did not affect performance in the DCD task, suggesting that the effec t of scopolamine is not mediated by a single muscarinic receptor subty pe. The results furthermore indicate that the cholinergic system in th e dmPFC does not play a specific role in WM processes in the DCD task. Furthermore, the results suggest that the dmPFC cholinergic system pl ays a role in the attentional processes involved in the DCD task.