Reinstatement of extinguished fear by beta-adrenergic arousal elicited by a conditioned context.
Five experiments examined the reinstatement of fear (freezing) produced by recent reexposure to a dangerous context. Rats were trained to fear a conditioned stimulus (CS) and a distinctive context with shock. The CS was then extinguished. A 2-min interval between reexposure to the dangerous context and presentation of the extinguished CS in a different context reinstated freezing when the CS was tested the next day. Propranolol (a beta-adrenergic antagonist) blocked reinstatement of extinguished fear without decreasing freezing to a nonextinguished CS. Administration of epinephrine (an adrenergic agonist) reinstated extinguished fear without reexposure to the dangerous context. The results suggest a role for beta-adrenergic activity elicited by exposure to a conditioned context in the reinstatement of extinguished fear.
Morris
Richard W
RW
School of Psychology, University of New South Wales, Sydney, NSW, Australia. rmorris@uvm.edu
Westbrook
R Frederick
RF
Killcross
A S
AS
D018663:Adrenergic Agents / Q000494:pharmacology*; D000818:Animals; D001245:Association Learning / Q000187:drug effects / Q000502:physiology; D001522:Behavior, Animal; D003214:Conditioning, Classical / Q000187:drug effects*; D003463:Cues; D004305:Dose-Response Relationship, Drug; D004597:Electroshock; D004837:Epinephrine / Q000494:pharmacology*; D005108:Extinction, Psychological / Q000187:drug effects*; D005239:Fear; D005795:Generalization, Stimulus; D008297:Male; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D018663:Adrenergic Agents; D011433:Propranolol; D004837:Epinephrine