| LeDoux Lab 2005 SfN Abstracts |
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| LATERAL AMYGDALA INACTIVATION ATTENUATES LICK SUPPRESSION IN A PARTIALLY REINFORCED FEAR CONDITIONING TASK | |
| J.C.Erlich*; D.E.A.Bush; J.E.LeDoux | |
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The lateral nucleus of the amygdala (LA) is the putative
neural substrate for Pavlovian fear conditioning. Lesions and pharmacological
inactivations of LA attenuate acquisition and expression of freezing
in Pavlovian fear conditioning. Most studies have focused on the role
of the amygdala in learning the association between a neutral conditioned
stimulus (CS; e.g. a tone) and an aversive unconditioned stimulus
(US; e.g. a shock), but it is not known if the LA is required for
the expression of fear responses to a well-learned, partially-reinforced
CS. We were specifically interested in testing the role of LA in lick
suppression, since this measure allows us to clearly define the temporal
onset and offset of suppression. Cannulae were bilaterally implanted
in the LA of Sprague-Dawley rats. After recovery, rats were trained
in a partial reinforcement task designed to produce intermediate levels
of suppression. The CS (12KHz pulsiform auditory, 80 dB, 20 sec) was
paired probabilistically with the US (200ms, 0.7 mA footshock) while
rats had free access to Kool-Aid. After behavior reached asymptotic
levels (8 sessions), each rat received both vehicle and muscimol (1.1
nmoles in 0.25  L)
infusions, counter-balanced, with 3 intervening sessions between infusions.
We found that the muscimol infusions significantly attenuated CS-evoked
lick suppression. Thus, the LA is required for suppression elicited
by a well-trained, partially reinforced fear CS.Support Contributed By: R37 MH38774, P50 MH58911, K05 MH067048. Jeffrey C Erlich is an HHMI pre-doctoral fellow. |
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| Program No. 415.5 Poster presentation:Monday, Nov. 14, 8:00 AM - 9:00 AM Location: HH28 |
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