Document Detail

Conditioned suppression and freezing as measures of aversive Pavlovian conditioning: effects of discrete amygdala lesions and overtraining.
MedLine Citation:
PMID:  15817185     Owner:  NLM     Status:  MEDLINE    
Freezing and suppression are measures of conditioned fear that correlate in unlesioned animals. Both the basolateral (BLA) and central (CeN) nuclei of the amygdala are required for conditioned freezing, though there can be recovery with overtraining. The neuroanatomical substrates of conditioned suppression are less clear, with evidence both for a specific requirement of the CeN and for disruption by BLA lesions. The present study investigated the impact of selective excitotoxic lesions of the BLA and CeN upon the acquisition and expression of conditioned fear, measured by freezing and both on-baseline and off-baseline conditioned suppression in the same rats. BLA and CeN lesions both abolished all measures of conditioned fear after 9 trials of fear conditioning. However, when conditioning was extended to 33 trials, whereas rats with combined lesions of both the BLA and CeN continued to show no conditioned fear responses, there was a pattern of recovery observed after selective lesions. There was a partial recovery of freezing with both lesions, and full recovery of conditioned suppression, except for off-baseline suppression in CeN lesioned rats. These results indicate that with few conditioning trials, both the BLA and CeN are required in a serial manner for conditioned fear responses, but that overtraining can mitigate such impairments, likely involving parallel pathways in and through the amygdala.
Jonathan L C Lee; Anthony Dickinson; Barry J Everitt
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-12-09
Journal Detail:
Title:  Behavioural brain research     Volume:  159     ISSN:  0166-4328     ISO Abbreviation:  Behav. Brain Res.     Publication Date:  2005 Apr 
Date Detail:
Created Date:  2005-04-08     Completed Date:  2005-07-19     Revised Date:  2014-02-19    
Medline Journal Info:
Nlm Unique ID:  8004872     Medline TA:  Behav Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  221-33     Citation Subset:  IM    
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MeSH Terms
Amygdala / physiology*
Avoidance Learning / physiology*
Conditioning, Classical / physiology*
Fear / physiology
Freezing Reaction, Cataleptic / physiology*
Rats, Inbred Strains
Reactive Inhibition*
Grant Support
G9537855//Medical Research Council

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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