title: Timing of extinction relative to acquisition: a parametric analysis of fear extinction in humans.
abstract: Fear extinction is a reduction in conditioned fear following repeated exposure to the feared cue in the absence of any aversive event. Extinguished fear often reappears after extinction through spontaneous recovery. Animal studies suggest that spontaneous recovery can be abolished if extinction occurs within minutes of acquisition. However, a limited number of human extinction studies have shown that short interval extinction does not prevent the return of fear. For this reason, we performed an in-depth parametric analysis of human fear extinction using fear-potentiated startle. Using separate single-cue and differential conditioning paradigms, participants were fear conditioned and then underwent extinction either 10 min (Immediate) or 72 hr (Delayed) later. Testing for spontaneous recovery occurred 96 hr after acquisition. In the single cue paradigm, the Immediate and Delayed groups exhibited differences in context, but not fear, conditioning. With differential conditioning, there were no differences in context conditioning and the Immediate group displayed less spontaneous recovery. Thus, the results remain inconclusive regarding spontaneous recovery and the timing of extinction and are discussed in terms of performing translational studies of fear in humans.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA. seth.norrholm@va.gov
authors.forename: Seth D
authors.initials: SD
authors.lastname: Norrholm
authors.forename: Bram
authors.initials: B
authors.lastname: Vervliet
authors.forename: Tanja
authors.initials: T
authors.lastname: Jovanovic
authors.forename: William
authors.initials: W
authors.lastname: Boshoven
authors.forename: Karyn M
authors.initials: KM
authors.lastname: Myers
authors.forename: Michael
authors.initials: M
authors.lastname: Davis
authors.forename: Barbara
authors.initials: B
authors.lastname: Rothbaum
authors.forename: Erica J
authors.initials: EJ
authors.lastname: Duncan
mesh_terms: D000161:Acoustic Stimulation / Q000009:adverse effects; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001362:Avoidance Learning / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D003463:Cues; D005108:Extinction, Psychological / Q000502:physiology*; D005239:Fear / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology; D013216:Reflex, Startle / Q000502:physiology*; D013997:Time Factors