| LeDoux Lab 2005 SfN Abstracts |
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| ESCAPE FROM FEAR: A DETAILED BEHAVIORAL ANALYSIS OF TWO ATYPICAL RESPONSES REINFORCED BY CS-TERMINATION | |
| C.K.Cain*; J.E.LeDoux | |
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| In escape from fear (EFF) rats learn a response (Re)
that eliminates exposure to a fear-eliciting conditioned stimulus
(CS). The aversive nature of the CS is believed to motivate EFF learning,
and Re is negatively reinforced by CS termination. EFF learning is
important theoretically and also as a model for active coping. However,
it is controversial, partly because it has been difficult to reliably
reproduce. The goals of this study were to address past concerns about
EFF learning and to design a reliable protocol amenable to mechanistic
dissection. Two atypical EFF responses, rearing and headpoking, were examined with a novel protocol. A day after Pavlovian tone-shock pairings, rats were placed in a novel chamber for a single EFF training session. LEARN rats received 25 massed CS presentations that terminated after 60s or when the rat made the Re. YOKED rats received identical CS patterns independent of their behavior. A day later, rats were returned to the chamber for a long-term test (1 x 10-min. CS). Freezing, rearing, headpoking and grooming were analyzed for both sessions. There was strong evidence for response-specific EFF learning when rearing was reinforced by CS-termination. LEARN rats reared twice as much as YOKED rats in both the training and testing sessions, but showed equal headpoking and grooming behavior. While freezing was initially the same between the groups, LEARN rats extinguished faster and froze less the next day, suggesting that EFF learning results in faster elimination of a passive defensive reaction. Other controls demonstrated that EFF learning is aversively-motivated and controlled by the CS. Finally, when headpoking was reinforced with CS-termination, there were no differences in any of the behaviors, suggesting that not all responses can be learned with EFF training. Thus, our protocol results in robust, long-lasting EFF learning during a single 33-minute session that may be ideal for mechanistic studies. Indeed, we are presently investigating the role of forebrain regions in EFF learning. Support Contributed By: NIMH grants |
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| Program No. 415.3. Poster presentation:Monday, Nov. 14, 10:00 AM - 11:00 AM Location: HH26 |
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