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


METHODS
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.


METHODS
Academic medical center.


METHODS
Paid normal volunteers.


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.
Pace-Schott
Edward F
EF
Harvard Medical School, Department of Psychiatry, Center for Sleep & Cognition, Beth Israel Deaconess Medical Center Boston, MA 02215, USA. epacesch@bidmc.harvard.edu
Milad
Mohammed R
MR
Orr
Scott P
SP
Rauch
Scott L
SL
Stickgold
Robert
R
Pitman
Roger K
RK
D000293:Adolescent; D000328:Adult; D001143:Arousal; D001245:Association Learning; D003214:Conditioning, Classical; D004597:Electroshock; D005108:Extinction, Psychological; D005239:Fear; D005260:Female; D005712:Galvanic Skin Response; D005795:Generalization, Stimulus; D006801:Humans; D008297:Male; D011939:Mental Recall; D012890:Sleep; D014851:Wakefulness; D055815:Young Adult