Send to

Choose Destination
Behav Neurosci. 1998 Aug;112(4):952-65.

The effects of cocaine, amphetamine, and the dopamine D1 receptor agonist SKF 38393 on fear extinction as measured with potentiated startle: implications for psychomotor stimulant psychosis.

Author information

Department of Psychology, University of Saskatchewan, Saskatoon, Canada.


Using Pavlovian conditioned increases in the amplitude of the acoustic startle reflex as a behavioral indicator of fear motivation, the authors previously showed a resistance to extinction after repeated associations of cocaine with the fear-evoking conditioned stimulus (CS). In Experiment 1, acute administration of cocaine, amphetamine, and the dopamine (DA) D1 receptor agonist SKF 38393 produced a similar fear enhancement. In Experiment 2, a noncontingent injection of cocaine and SKF 38393 provoked a CS potentiation of acoustic startle in fear-extinguished laboratory rats. Potential behavioral, neurochemical, and neuroendocrine explanations for the effects of psychomotor stimulants on conditional fear were discussed. It was suggested that DA agonist drugs increase fear expression possibly by activating mesoamygdaloid associative neurocircuitry involved in excitatory conditioned fear reactions.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for American Psychological Association
Loading ...
Support Center