title: Circadian waveform bifurcation, but not phase-shifting, leaves cued fear memory intact.
abstract: In mammals, memory acquisition and retrieval can be affected by time of day, as well as by manipulations of the light/dark cycle. Under bifurcation, a manipulation of circadian waveform, two subjective days and nights are experimentally induced in rodents. We examined the effect of bifurcation on Pavlovian fear conditioning, a prominent model of learning and memory. Here we demonstrate that bifurcation of the circadian waveform produces a small deficit in acquisition, but not on retrieval of fear memory. In contrast, repeated phase-shifting in a simulated jet-lag protocol impairs retrieval of memory for cued fear. The results have implications for those attempting to adjust to shift-work or other challenging schedules.
authors.affiliation: Center for Circadian Biology, University of San Diego, California, 9500 Gilman Dr, La Jolla, CA 92093, USA; Department of Psychology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA. Electronic address: emharrison@ucsd.edu.
authors.forename: E M
authors.initials: EM
authors.lastname: Harrison
authors.affiliation: Neurobiology of Addiction Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Carmack
authors.affiliation: Department of Psychology and Neuroscience, 417 Chapel Drive, Duke University, Durham, NC 27708-0086, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Block
authors.affiliation: Center for Circadian Biology, University of San Diego, California, 9500 Gilman Dr, La Jolla, CA 92093, USA; Department of Psychology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA.
authors.forename: J
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Psychology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA.
authors.forename: S G
authors.initials: SG
authors.lastname: Anagnostaras
authors.affiliation: Center for Circadian Biology, University of San Diego, California, 9500 Gilman Dr, La Jolla, CA 92093, USA; Department of Psychology, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Gorman
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001288:Attention / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D004597:Electroshock / Q000009:adverse effects; D005239:Fear; D005260:Female; D008297:Male; D008568:Memory / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000502:physiology*
keywords: Bifurcation; Circadian; Learning; Memory; Pavlovian fear conditioning; Waveform