Effects of pre- or post-training entorhinal cortex AP5 injection on fear conditioning

Effects of pre- or post-training entorhinal cortex AP5 injection on fear conditioning

Author Schenberg, E. E. Google Scholar
Soares, JCK Google Scholar
Oliveira, MGM Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract Fear conditioning is one of the most studied paradigms to assess the neural basis of emotional memory. the circuitry involves NNMA 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. (c) 2005 Elsevier Inc. All fights reserved.
Keywords acquisition
AP5
consolidation
entorhinal cortex
fear conditioning
memory
NMDA
Language English
Date 2005-11-15
Published in Physiology & Behavior. Oxford: Pergamon-Elsevier B.V., v. 86, n. 4, p. 508-515, 2005.
ISSN 0031-9384 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 508-515
Origin http://dx.doi.org/10.1016/j.physbeh.2005.08.032
Access rights Closed access
Type Article
Web of Science ID WOS:000233479800012
URI http://repositorio.unifesp.br/handle/11600/28550

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