LeDoux Lab 2009 SfN Abstracts
 
Program#/Poster#: 479.18/FF119
Title: Retrieval-induced strengthening of fear memory: Interactions with beta-adrenergic blockade
Location: South Hall A
Presentation Time: Monday, Oct 19, 2009, 2:00 PM - 3:00 PM
Authors: M. H. MONFILS1,2, L. DIAZ-MATAIX2, D. BUSH2, J. VUJOVIC2, J. DEBIEC3, V. DOYERE4, J. E. LEDOUX5,2;
1Dept. of Psychology, Univ. of Texas At Austin, Austin, TX; 2Ctr. for Neural Sci., 3Dept. of Psychiatry, New York Univ., New York, NY; 4Univ. Paris-Sud, Orsay, France; 5Emotional Brain Inst., Orangeburg, NY
Abstract: Evidence suggests that previously consolidated memories revert to a mutable state when subsequently retrieved, and that a second cycle of protein synthesis is then required to restore the stable condition of memories: a process termed reconsolidation. Pharmacologically interfering with mechanisms triggered during retrieval enables the targeted modification of memories in the lateral nucleus of the amygdala (LA). A number of studies initially focused on attenuating fear using this paradigm, yet recent evidence also suggests that fear memories can be strengthened pharmacologically at the time of retrieval (e.g., Tronson et al., 2007). We, and others, have recently shown that fear memory retrieval induces an increase in GluR1 phosphorylation at ser845 in the LA (Monfils et al., 2009 ; Ben Mamou et al., 2008). In addition, we have shown that post consolidation retrieval induces a specific increase in short-latency synaptic efficacy in the LA, above and beyond that induced by fear conditioning (Doyere et al., 2007). Here, we sought to examine the effect of a retrieval trial on the strength of a fear memory, and its susceptibility to extinction. We show that a single retrieval trial presented 24 hours prior to a session in which the CS was repeatedly presented (extinction) leads to a resistance to extinguish relative to a group that did not receive a CS retrieval. We next demonstrate that a systemic injection of propranolol at the time of retrieval leads to a reduction in freezing (reconsolidation blockade). In addition, propranolol administered at the time of retrieval shows an effect on the susceptibility to extinguish 24 hours later that is dependent on strength of conditioning. The results are discussed in the context of reconsolidation-extinction boundaries, and their interactions in mediating fear memories’ susceptibility to attenuation.
Support: NIH R37 MH038774 to JEL
NIH P50 MH058911 to JEL
NIH R01 MH046516 to JEL
AHFMR, NSERC, and CIHR to MHM
FUL to LDM