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Effects of pre- or post-training entorhinal cortex AP5 injection on fear conditioning.
Physiol Behav. 2005 Nov 15; 86(4):508-15.PB

Abstract

Fear conditioning is one of the most studied paradigms to assess the neural basis of emotional memory. The circuitry involves NMDA receptor activation in the amygdala and, in the case of contextual conditioning, in the hippocampus. Entorhinal cortex is one of the major input/output structures to the hippocampus and also projects to the amygdala, both through glutamatergic transmission. Other learning tasks involving hippocampus and amygdala, such as inhibitory avoidance, require entorhinal cortex during acquisition and consolidation. However, the involvement of NMDA receptors mediated transmission in entorhinal cortex in fear conditioning acquisition and consolidation is not clear. To investigate that issue, rats were trained in fear conditioning to both contextual and tone conditioned stimulus. Immediately before, immediately, 30 or 90 min after training they received NMDA antagonist AP5 or saline injections bilaterally in the entorhinal cortex (AP-6.8 mm, L +/-5.0 mm DV-6.8 mm). Contextual fear conditioning was measured 24 h after training, and tone fear conditioning 48 h after training. AP5 injections selectively impaired contextual fear conditioning only when injected pre-training. Post-training injections had no effect. These findings suggest that entorhinal cortex NMDA receptors are necessary for acquisition, but not for consolidation, of contextual fear conditioning. On the other hand, both acquisition and consolidation of tone fear conditioning seem to be independent of NMDA receptors in the entorhinal cortex.

Authors+Show Affiliations

Psychobiology Department, Universidade Federal de São Paulo-UNIFESP, São Paulo, SP, 04024-002, Brazil.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16182326

Citation

Schenberg, Eduardo Ekman, et al. "Effects of Pre- or Post-training Entorhinal Cortex AP5 Injection On Fear Conditioning." Physiology & Behavior, vol. 86, no. 4, 2005, pp. 508-15.
Schenberg EE, Soares JC, Oliveira MG. Effects of pre- or post-training entorhinal cortex AP5 injection on fear conditioning. Physiol Behav. 2005;86(4):508-15.
Schenberg, E. E., Soares, J. C., & Oliveira, M. G. (2005). Effects of pre- or post-training entorhinal cortex AP5 injection on fear conditioning. Physiology & Behavior, 86(4), 508-15.
Schenberg EE, Soares JC, Oliveira MG. Effects of Pre- or Post-training Entorhinal Cortex AP5 Injection On Fear Conditioning. Physiol Behav. 2005 Nov 15;86(4):508-15. PubMed PMID: 16182326.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of pre- or post-training entorhinal cortex AP5 injection on fear conditioning. AU - Schenberg,Eduardo Ekman, AU - Soares,Juliana Carlota Kramer, AU - Oliveira,Maria Gabriela Menezes, Y1 - 2005/09/21/ PY - 2005/05/05/received PY - 2005/07/18/revised PY - 2005/08/02/accepted PY - 2005/9/27/pubmed PY - 2006/1/18/medline PY - 2005/9/27/entrez SP - 508 EP - 15 JF - Physiology & behavior JO - Physiol Behav VL - 86 IS - 4 N2 - Fear conditioning is one of the most studied paradigms to assess the neural basis of emotional memory. The circuitry involves NMDA receptor activation in the amygdala and, in the case of contextual conditioning, in the hippocampus. Entorhinal cortex is one of the major input/output structures to the hippocampus and also projects to the amygdala, both through glutamatergic transmission. Other learning tasks involving hippocampus and amygdala, such as inhibitory avoidance, require entorhinal cortex during acquisition and consolidation. However, the involvement of NMDA receptors mediated transmission in entorhinal cortex in fear conditioning acquisition and consolidation is not clear. To investigate that issue, rats were trained in fear conditioning to both contextual and tone conditioned stimulus. Immediately before, immediately, 30 or 90 min after training they received NMDA antagonist AP5 or saline injections bilaterally in the entorhinal cortex (AP-6.8 mm, L +/-5.0 mm DV-6.8 mm). Contextual fear conditioning was measured 24 h after training, and tone fear conditioning 48 h after training. AP5 injections selectively impaired contextual fear conditioning only when injected pre-training. Post-training injections had no effect. These findings suggest that entorhinal cortex NMDA receptors are necessary for acquisition, but not for consolidation, of contextual fear conditioning. On the other hand, both acquisition and consolidation of tone fear conditioning seem to be independent of NMDA receptors in the entorhinal cortex. SN - 0031-9384 UR - https://www.unboundmedicine.com/medline/citation/16182326/Effects_of_pre__or_post_training_entorhinal_cortex_AP5_injection_on_fear_conditioning_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0031-9384(05)00349-5 DB - PRIME DP - Unbound Medicine ER -