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Glutamate receptors in the medial geniculate nucleus are necessary for expression and extinction of conditioned fear in rats.
Neurobiol Learn Mem. 2009 Nov; 92(4):581-9.NL

Abstract

Auditory fear conditioning requires anatomical projections from the medial geniculate nucleus (MGN) of the thalamus to the amygdala. Several lines of work indicate that the MGN is a critical sensory relay for auditory information during conditioning, but is not itself involved in the encoding of long-term fear memories. In the present experiments, we examined whether the MGN plays a similar role in the extinction of conditioned fear. Twenty-four hours after Pavlovian fear conditioning, rats received bilateral intra-thalamic infusions of either with NBQX (an AMPA receptor antagonist; Experiment 1) or MK-801 (an NMDA receptor antagonist; Experiment 1), anisomycin (a protein synthesis inhibitor; Experiment 2) or U0126 (a MEK inhibitor; Experiment 3) immediately prior to an extinction session in a novel context. The next day rats received a tone test in a drug-free state to assess their extinction memory; freezing served as an index of fear. Glutamate receptor antagonism prevented both the expression and extinction of conditioned fear. In contrast, neither anisomycin nor U0126 affected extinction. These results suggest that the MGN is a critical sensory relay for auditory information during extinction training, but is not itself a site of plasticity underlying the formation of the extinction memory.

Authors+Show Affiliations

Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109, United States.No affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

19632347

Citation

Orsini, Caitlin A., and Stephen Maren. "Glutamate Receptors in the Medial Geniculate Nucleus Are Necessary for Expression and Extinction of Conditioned Fear in Rats." Neurobiology of Learning and Memory, vol. 92, no. 4, 2009, pp. 581-9.
Orsini CA, Maren S. Glutamate receptors in the medial geniculate nucleus are necessary for expression and extinction of conditioned fear in rats. Neurobiol Learn Mem. 2009;92(4):581-9.
Orsini, C. A., & Maren, S. (2009). Glutamate receptors in the medial geniculate nucleus are necessary for expression and extinction of conditioned fear in rats. Neurobiology of Learning and Memory, 92(4), 581-9. https://doi.org/10.1016/j.nlm.2009.07.007
Orsini CA, Maren S. Glutamate Receptors in the Medial Geniculate Nucleus Are Necessary for Expression and Extinction of Conditioned Fear in Rats. Neurobiol Learn Mem. 2009;92(4):581-9. PubMed PMID: 19632347.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Glutamate receptors in the medial geniculate nucleus are necessary for expression and extinction of conditioned fear in rats. AU - Orsini,Caitlin A, AU - Maren,Stephen, Y1 - 2009/07/24/ PY - 2009/04/28/received PY - 2009/07/14/revised PY - 2009/07/21/accepted PY - 2009/7/28/entrez PY - 2009/7/28/pubmed PY - 2009/12/16/medline SP - 581 EP - 9 JF - Neurobiology of learning and memory JO - Neurobiol Learn Mem VL - 92 IS - 4 N2 - Auditory fear conditioning requires anatomical projections from the medial geniculate nucleus (MGN) of the thalamus to the amygdala. Several lines of work indicate that the MGN is a critical sensory relay for auditory information during conditioning, but is not itself involved in the encoding of long-term fear memories. In the present experiments, we examined whether the MGN plays a similar role in the extinction of conditioned fear. Twenty-four hours after Pavlovian fear conditioning, rats received bilateral intra-thalamic infusions of either with NBQX (an AMPA receptor antagonist; Experiment 1) or MK-801 (an NMDA receptor antagonist; Experiment 1), anisomycin (a protein synthesis inhibitor; Experiment 2) or U0126 (a MEK inhibitor; Experiment 3) immediately prior to an extinction session in a novel context. The next day rats received a tone test in a drug-free state to assess their extinction memory; freezing served as an index of fear. Glutamate receptor antagonism prevented both the expression and extinction of conditioned fear. In contrast, neither anisomycin nor U0126 affected extinction. These results suggest that the MGN is a critical sensory relay for auditory information during extinction training, but is not itself a site of plasticity underlying the formation of the extinction memory. SN - 1095-9564 UR - https://www.unboundmedicine.com/medline/citation/19632347/Glutamate_receptors_in_the_medial_geniculate_nucleus_are_necessary_for_expression_and_extinction_of_conditioned_fear_in_rats_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1074-7427(09)00144-0 DB - PRIME DP - Unbound Medicine ER -