Reinstatement of Extinguished Fear by β-Adrenergic Arousal Elicited by a Conditioned Context

• Published in: Behavioral neuroscience 2005-12, Vol.119 (6), p.1662-1671
• Main Authors: Morris, Richard W, Westbrook, R. Frederick, Killcross, A. S
• Format: Article
• Language: English
• Subjects: Adrenergic Agents - pharmacology; Animal; Animal behavior; Animals; Association Learning - drug effects; Association Learning - physiology; Behavior, Animal; Behavioral psychophysiology; Biological and medical sciences; Conditioned Fear; Conditioning; Conditioning, Classical - drug effects; Cues; Dose-Response Relationship, Drug; Electroshock; Epinephrine; Epinephrine - pharmacology; Experiments; Extinction (Learning); Extinction, Psychological - drug effects; Fear; Fear & phobias; Fundamental and applied biological sciences. Psychology; Generalization, Stimulus; Learning. Memory; Male; Neurology; Neurotransmission and behavior; Propranolol; Propranolol - pharmacology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Wistar; Rodents; Time Factors
• ISSN: 0735-7044; 1939-0084
• DOI: 10.1037/0735-7044.119.6.1662

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 β-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 β-adrenergic activity elicited by exposure to a conditioned context in the reinstatement of extinguished fear.