title: Memory retrieval in response to partial cues requires NMDA receptor-dependent neurotransmission in the medial prefrontal cortex.
abstract: The medial prefrontal cortex (mPFC) has been suggested to play a crucial role in retrieving detailed contextual information about a previous learning episode in response to a single retrieval cue. However, few studies investigated the neurochemical mechanisms that mediate the prefrontal retrieval process. In the current study, we examined whether N-methyl-D-aspartate receptors (NMDARs) in the mPFC were necessary for retrieval of a well-learned spatial location on the basis of partial or degraded spatial cues. Rats were initially trained to find a hidden platform in the Morris water maze using four extramaze cues in the surrounding environment. Their retrieval performance was subsequently tested under different cue conditions. Infusions of DL-2-amino-5-phosphonovaleric acid (APV), a NMDAR antagonist, significantly disrupted memory retrieval when three of the original cues were removed. By contrast, APV injections into the mPFC did not affect animals' retrieval performance when the original cues were presented or when three novels landmarks were added alongside the original cues. These results indicate that prefrontal NMDARs are required for memory retrieval when allocentric spatial information is degraded. NMDAR-dependent neurotransmission in the mPFC may facilitate an active retrieval process to reactivate complete contextual representations associated with partial retrieval cues.
authors.affiliation: Department of Psychology, Korea University, Seoul 136-701, Republic of Korea; Department of Psychology, University of Washington, Seattle, WA 98195, USA.
authors.forename: Yong Sang
authors.initials: YS
authors.lastname: Jo
authors.affiliation: Department of Psychology, Korea University, Seoul 136-701, Republic of Korea. Electronic address: j-schoi@korea.ac.kr.
authors.forename: June-Seek
authors.initials: JS
authors.lastname: Choi
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D003463:Cues; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D011939:Mental Recall / Q000187:drug effects / Q000502:physiology*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate
keywords: Memory retrieval; NMDA receptors; Prefrontal cortex; Rat; Spatial memory