Retention of a 24-hour time memory in Syrian hamsters carrying the 20-hour short circadian period mutation in casein kinase-1e (ck1etau/tau)

Sean W. Cain, Jeena Yoon, Tenjin C Shreshtha, Martin R. Ralph

Research output: Contribution to journalArticleResearchpeer-review

8 Citations (Scopus)


Circadian rhythmic expression of conditioned place avoidance (CPA) was produced in Syrian hamsters homozygous for the circadian short period mutation, tau. In constant dim red light neither the 20 h endogenous period, nor a 20 h place conditioning schedule eliminated the 24 h modulation of CPA behavior described previously for wild type (wt) hamsters and other species. Tau mutants exhibited a 20 h rhythm superimposed on the 24 h modulation. The 20 h component was removed selectively with lesions of the suprachiasmatic nucleus. Wt animals conditioned on a 20 h schedule did not produce a 20 h rhythm, but still expressed the 24 h modulation. The results show that the context entrainable oscillator (CEO) underlying memory for the timing of an unconditioned stimulus, retains a period of about 24 h regardless of clock gene background (tau mutation) and/or the conditioning schedule (24 vs 20 h). Therefore the CEO responsible for time memory is distinct from the biological clock controlling activity; the underlying circadian molecular mechanisms may differ from the ubiquitous transcription–translation feedback oscillator; and time memory itself is not classically conditioned.
Original languageEnglish
Pages (from-to)171-177
Number of pages7
JournalNeurobiology of Learning and Memory
Publication statusPublished - Oct 2014
Externally publishedYes

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