| 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 |