| Program#/Poster#: |
591.20/UU7 |
| Title: |
The amygdala encodes specific sensory
features of an aversive reinforcer |
| Location: |
Washington Convention Center: Hall A-C
|
| Presentation Time: |
Tuesday, Nov 18, 2008, 11:00 AM -12:00
PM |
| Authors: |
*J. DEBIEC1,2,
V. DOYERE1,3, L. DÍAZ-MATAIX1, D. BUSH1,
J. LEDOUX1;
1Ctr. for Neural Sci., New York Univ., New York, NY; 2Dept
Psychiatry, NYUSM, New York, NY; 3Namc, CNRS-UMR8620, Univ Paris-Sud,
France |
| Abstract: |
Research on the neural basis of fear
conditioning points to the lateral amygdala (LA) as a key interface where
a harmful unconditioned stimulus (US) becomes associated with an initially
neutral conditioned stimulus (CS). Retrieval of a fear memory triggers reconsolidation
processes that require protein synthesis in the LA. In studies to date,
memories have been reactivated by presenting a CS. Little is known about
the role of the US in initiating reconsolidation processes, but it is conceivable
that a representation of the sensory properties of the US may be stored
in the amygdala and may trigger reconsolidation of the CS-US association
if activated by the US. We have previously demonstrated that reconsolidation
in LA is CS-selective. Here we asked whether reconsolidation in LA is a
US-selective process. Using two distinct USs (eyelid-shock and foot-shock)
each paired with a distinct auditory CS (1 kHz, 50 ms pips or FM sweeps,
10-15 kHz, 250 ms) and an extinction protocol, we first demonstrated that
post-extinction exposure to a US leads to the selective reinstatement of
fear responses to the CS that was paired with that US. Next we implanted
other group of rats with bilateral cannulae in the LA. Rats were conditioned
as above using two distinct USs, each paired with a distinct CS. On the
day following training, one of the two USs was presented in order to reactivate
the memory. This was followed by intra-LA infusion of protein synthesis
inhibitor (anisomycin). 24 later, rats were tested for fear retention. Fear
responses (freezing) to each of the tones were measured. We found that intra-LA
blockade of protein synthesis following an exposure to a particular US disrupts
fear responding only to the CS previously paired with that US. Together
these results suggest that independent fear memories, linked to specific
USs, are formed, stored, retrieved and reconsolidated through LA-dependent
mechanisms. Thus, LA remembers fear through encoding of specific aversive
features of the US, a finding not predicted by current amygdala-based models
of fear learning. |
| Support: |
R37 MH038774 |
|
P50 MH058911 |
|
R01 MH046516, K05 MH067048 |
|
CNRS-PICS, NSF # OISE-0340607 |
|
Fullbright Spanish Ministry |