Blockade of NMDA receptors located at the dorsomedial prefrontal cortex impairs spatial working memory in rats

WE investigated the effects of NMDA and muscarinic acetylcholine receptor b lockade in the rostral part of dorsomedial (dmPFC) and dorsolateral prefron tal cortex (dlPFC) on spatial working memory (SWM) (delayed non-matching to position task (DNMTP)). The NMDA antagonist, CPP (0.01, 0.03, 0.1 and 0.3 mu g/hemisphere) and the muscarinic antagonist, scopolamine (10 mu g/hemisp here) were locally infused into the brain of male Wistar rats. In the mPFC CPP 0.1 mu g disrupted SWM delay-dependently and CPP 0.3 mu g caused a dela y-independent performance deficit. Scopolamine disrupted non-cognitive perf ormance, but did not affect SWM accuracy. In the dlPFC, scopolamine or lowe r doses of CPP did not affect SWM accuracy, but CPP 0.3 mu g disrupted non- cognitive performance. We concluded that the NMDA receptors in the dmPFC re gulate SWM processes, whereas the muscarinic receptors in the dmPFC mediate non-cognitive performance in the DNMTP task. (C) 1999 Lippincott Williams & Wilkins.