Document Detail

Posttraining lesion of the superior colliculus interferes with feature-negative discrimination of fear-potentiated startle.
MedLine Citation:
PMID:  12798272     Owner:  NLM     Status:  MEDLINE    
Though much is known about the neural circuits involved in the elicitation of fear, little is known about the neural circuits responsible for the reduction of fear. The present experiments investigated the contribution of the superior colliculus (SC) and the dorsal periacquaductal gray (dPAG) in the reduction of conditioned fear produced by an auditory feature trained in a feature-negative discrimination procedure. In this procedure, light plus foot shock training trials are interspersed with trials in which the light is preceded by a noise and this noise and light compound is not followed by foot shock. At the end of this feature-negative discrimination training, rats were given excitotoxic lesions of the SC or dPAG. Feature-negative discrimination of fear was assessed with the fear-potentiated startle effect in which conditioned fear is operationally defined as potentiated startle amplitude in the presence versus the absence of the light. Feature-negative discrimination of fear is evidenced by a reduction in fear-potentiated startle to the light when the noise feature accompanies the light. Lesions of the SC, but not the dPAG, interfered with feature-negative discrimination of fear-potentiated startle suggesting that the SC plays a role in feature-negative discrimination of fear. Both SC and dPAG lesions facilitated startle amplitude in the absence of the light suggesting that these structures may exert a tonic inhibition on the acoustic startle reflex. The SC receives polymodal sensory information and is known to project forebrain areas involved in the production of conditioned fear. Thus, the SC may be an important component of the feature-negative discrimination circuit.
Jaylyn Waddell; Scott Heldt; William A Falls
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Behavioural brain research     Volume:  142     ISSN:  0166-4328     ISO Abbreviation:  Behav. Brain Res.     Publication Date:  2003 Jun 
Date Detail:
Created Date:  2003-06-11     Completed Date:  2003-09-30     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8004872     Medline TA:  Behav Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  115-24     Citation Subset:  IM    
Department of Psychology, The University of Vermont, John Dewey Hall, 2 Colchester Ave., Burlington, VT 05405, USA.
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MeSH Terms
Acoustic Stimulation / psychology
Conditioning, Classical / drug effects
Discrimination Learning / drug effects,  physiology*
Fear / physiology*
Photic Stimulation
Rats, Sprague-Dawley
Startle Reaction / physiology*
Strychnine / pharmacology
Superior Colliculi / physiology*,  surgery
Time Factors
Grant Support
Reg. No./Substance:

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

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