Intra-amygdala blockade of the NR2B subunit of the NMDA receptor disrupts the acquisition but not the expression of fear conditioning

S. M. Rodrigues, G. E. Schafe, J. E. LeDoux

Research output: Contribution to journalArticle

Abstract

The lateral nucleus of the amygdala (LA) is an essential component of the neural circuitry underlying Pavlovian fear conditioning. Although blockade of NMDA receptors in LA and adjacent areas before training disrupts the acquisition of fear conditioning, blockade before testing also often disrupts the expression of fear responses. With this pattern of results, it is not possible to distinguish a contribution of NMDA receptors to plasticity from a role in synaptic transmission. In past studies, NMDA blockade has been achieved using the antagonist D,L-2-amino-5-phosphovalerate, which blocks the entire heteromeric receptor complex. The present experiments examined the effects of selective blockade of the NR2B subunit of the NMDA receptor in LA using the selective antagonist ifenprodil. Systemic injections of ifenprodil before training led to a dose-dependent impairment in the acquisition of auditory and contextual fear conditioning, whereas injections before testing had no effect. Intra-amygdala infusions of ifenprodil mirrored these results and, in addition, showed that the effects are attributable to a disruption of fear learning rather than a disruption of memory consolidation. NMDA receptors in LA are thus involved in fear conditioning, and the NR2B subunit appears to make unique contributions to the underlying plasticity.

Original languageEnglish (US)
Pages (from-to)6889-6896
Number of pages8
JournalJournal of Neuroscience
Volume21
Issue number17
DOIs
StatePublished - Sep 1 2001

Keywords

  • Amygdala
  • Fear
  • Ifenprodil
  • Learning
  • NMDA receptor
  • NR2B subunit

ASJC Scopus subject areas

  • Neuroscience(all)

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