Effects of pre or posttraining dorsal hippocampus D-AP5 injection on fear conditioning to tone, background, and foreground context

• Published in: Hippocampus 2008-11, Vol.18 (11), p.1089-1093
• Main Authors: Schenberg, Eduardo Ekman, Oliveira, Maria Gabriela Menezes
• Format: Article
• Language: English
• Subjects: 2-Amino-5-phosphonovalerate - administration & dosage; Animals; AP5; Conditioning, Classical - drug effects; Conditioning, Classical - physiology; Excitatory Amino Acid Antagonists - administration & dosage; Fear - psychology; fear conditioning; hippocampus; Hippocampus - drug effects; Hippocampus - physiology; Male; memory; NMDA receptors; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate - antagonists & inhibitors; Receptors, N-Methyl-D-Aspartate - drug effects
• ISSN: 1050-9631; 1098-1063
• DOI: 10.1002/hipo.20475

NMDA receptor antagonist D‐AP5 was injected into the dorsal hippocampus of Wistar rats before or immediately after the training session in fear conditioning. Training was conducted both with signaled (background context) or unsignaled (foreground context) footshocks. Contextual fear conditioning was assessed 24 h later and tone fear conditioning 48 h after training (only in the signaled footshock condition). Pretraining injections impaired conditioned fear to contextual features, both in background and foreground configurations, whereas tone fear conditioning was left intact. Posttraining injections were ineffective in all cases. We conclude that dorsal hippocampal NMDA receptors are required for contextual fear acquisition independently of context saliency and that they are not required to early consolidation processes. © 2008 Wiley‐Liss, Inc.