LeDoux Lab 2008 SfN Abstracts
 
Program#/Poster#: 591.21/UU8
Title: Does the US reactivation trigger a reconsolidation of a CS representation in the LA?
Location: Washington Convention Center: Hall A-C
Presentation Time: Tuesday, Nov 18, 2008, 8:00 AM - 9:00 AM
Authors: *L. DIAZ-MATAIX1, J. DEBIEC2,1, J. E. LEDOUX1, V. DOYERE3;
1Ctr. Neural Sci., New York Univ., New York, NY; 2Dept. of Psychiatry, New York Univ. Sch. of Med., New York, NY; 3Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication (NAMC), Ctr. Natl. de la Recherche Scientifique (CNRS), UMR8620, Univ. Paris-Sud, Orsay, France
Abstract: When a neutral stimulus, such as tone conditioned stimulus (CS), is paired with a noxious unconditioned stimulus (US), such as footshock, it acquires the ability to elicit fear responses through a Pavlovian associative learning process. Fear memories, once consolidated in a long-term stable state, are, when reactivated, updated through a reconsolidation process. Recently, we have shown that fear memory retrieval triggered by a CS presentation produces a synaptic potentiation in the lateral amygdala (LA) that is selective to the reactivated memory, and that disruption of reconsolidation is selective to the reactivated CS and is correlated with a reduction of synaptic potentiation in the LA (Doyère et al., 2007). Here, we ask whether, as does the CS, the US, as with the CS, can reactivate the CS representation in the LA and trigger its reconsolidation of the CS-US association in the LA. Rats were chronically implanted with bilateral cannulae in the LA, a recording electrode attached to the left cannula, and a stimulating electrode in the left auditory thalamus (MGm/PIN). Rats were then submitted to a training protocol in which one tone (1 kHz, 50 ms pips) was paired with eyelid shocks (USeye) and another tone (FM sweeps, 10-15 kHz, 250 ms) was paired with footshocks (USfoot). Rats were habituated, conditioned, and reactivated with USeye 30 min after intra-LA infusion of a MAP kinase inhibitor (U0126). Following reactivation, rats were tested for fear retention both at 3hr and ~24h later. Behavioral (freezing) and short-latency neurophysiological responses (field potentials in the LA and in the MGM/PIN) evoked by each of the tones were recorded and analysed during each phase of the experiment. Preliminary results show a selective deficit in long-term memory for the tone associated with the USeye reactivated in the presence of U0126. This selective behavioral deficit was accompanied by a long-term, but not a short-term, decrease in the potentiation of neurophysiological responses in the LA evoked by that tone. The question of whether the US presentation triggers a potentiation in the LA and whether the responses in the auditory thalamus show a similar pattern of results is under investigation. Thus the deficit in behavioral long-term memory is paralleled with by a the decrease in LA synapse plasticity suggests that the US triggers a reconsolidation of the associated-CS representation in the LA.
Support: Fullbright / Spanish Ministry of Science
R37 MH038774
P50 MH058911
R01 MH046516; K05 MH067048
CNRS-PICS, NSF # OISE-0340607