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Sleep. 2009 Jan;32(1):19-26.

Sleep promotes generalization of extinction of conditioned fear.

Author information

1
Harvard Medical School, Department of Psychiatry, Center for Sleep & Cognition, Beth Israel Deaconess Medical Center Boston, MA 02215, USA. epacesch@bidmc.harvard.edu

Abstract

STUDY OBJECTIVE:

To examine the effects of sleep on fear conditioning, extinction, extinction recall, and generalization of extinction recall in healthy humans.

DESIGN:

During the Conditioning phase, a mild, 0.5-sec shock followed conditioned stimuli (CS+s), which consisted of 2 differently colored lamps. A third lamp color was interspersed but never reinforced (CS-). Immediately after Conditioning, one CS+ was extinguished (CS+E) by presentation without shocks (Extinction phase). The other CS+ went unextinguished (CS+U). Twelve hours later, following continuous normal daytime waking (Wake group, N=27) or an equal interval containing a normal night's sleep (Sleep group, N=26), conditioned responses (CRs) to all CSs were measured (Extinction Recall phase). It was hypothesized that the Sleep versus Wake group would show greater extinction recall and/or generalization of extinction recall from the CS+E to the CS+U.

SETTING:

Academic medical center.

SUBJECTS:

Paid normal volunteers.

MEASUREMENTS AND RESULTS:

Square-root transformed skin conductance response (SCR) measured conditioned responding. During Extinction Recall, the Group (Wake or Sleep) x CS+ Type (CS+E or CS+U) interaction was significant (P = 0.04). SCRs to the CS+E did not differ between groups, whereas SCRs to the CS+U were significantly smaller in the Sleep group. Additionally, SCRs were significantly larger to the CS+U than CS+E in the Wake but not the Sleep group.

CONCLUSIONS:

After sleep, extinction memory generalized from an extinguished conditioned stimulus to a similarly conditioned but unextinguished stimulus. Clinically, adequate sleep may promote generalization of extinction memory from specific stimuli treated during exposure therapy to similar stimuli later encountered in vivo.

PMID:
19189775
PMCID:
PMC2625320
[Indexed for MEDLINE]
Free PMC Article

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