Background
The startle reflex is potentiated by aversive states. It has been proposed that phasic
startle potentiation to a threat cue and sustained startle potentiation to contextual
stimuli reflect distinct processes mediated by different brain structures. The present
study tested the hypothesis that alprazolam would reduce the sustained startle potentiation
to contextual threats but not the startle potentiation to a threat cue.
Methods
Sixteen healthy subjects received each of four treatments: placebo, .5 mg of alprazolam,
1 mg of alprazolam, and 50 mg of diphenhydramine (Benadryl) in a crossover design.
Participants were exposed to three conditions, including one in which predictable
aversive shocks were signaled by a cue, a second in which shocks were administered
unpredictably, and a third condition in which no shocks were anticipated. Acoustic
startle were delivered regularly across conditions.
Results
Phasic startle potentiation to the threat cue in the predictable condition was not
affected by alprazolam. In contrast, the sustained increase in startle in the predictable
and unpredictable conditions was reduced significantly by the high dose of alprazolam.
Conclusions
Startle responses to an explicit threat cue and to an aversive context are psychopharmacologically
distinct, suggesting that they may represent functionally dissociable aversive states.
Key Words
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Article info
Publication history
Published online: April 24, 2006
Accepted:
November 11,
2006
Received in revised form:
October 27,
2005
Received:
July 12,
2005
Identification
Copyright
© 2006 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
