Differential effects of dark pulses on the two components of split circadian activity rhythms in golden hamsters (original) (raw)

Summary

Single 6-h pulses of dark were presented to golden hamsters displaying split circadian activity rhythms in constant light. The differential responses of the split components immediately following a 6-h dark pulse suggests that each component has a separate and similar bidirectional phase response curve, similar in shape to that described by other investigators for non-split hamster activity rhythms. The steady-state phase shifts of the split components were more variable with accompanying changes in period, changes in the time-interval between components, and the presence of transients, reflecting the gradual re-establishment of the pre-pulse 180 ° phase relationship. In addition, dark pulse presentation sometimes resulted in the replacement of a single split component by a number of smaller, frequent bursts of activity; this indicates that there may be a population of tightly coupled oscillators underlying each split component.

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Abbreviations

CT :

circadian time

DD :

constant dark

LD :

light-dark

LL :

constant light

PRC :

phase response curve

τ:

period of circadian rhythm

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Authors and Affiliations

  1. Department of Zoology, University of Toronto, Toronto, Canada
    Jodi G. Lees & N. Mrosovsky
  2. Department of Psychology, University of Toronto, Toronto, Canada
    N. Mrosovsky
  3. Department of Psychiatry, Mount Sinai Hospital and University of Toronto, Toronto, Canada
    J. D. Hallonquist

Authors

  1. Jodi G. Lees
  2. J. D. Hallonquist
  3. N. Mrosovsky

Additional information

A preliminary report of this work was given by Lees and Hallonquist (1982)

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Lees, J.G., Hallonquist, J.D. & Mrosovsky, N. Differential effects of dark pulses on the two components of split circadian activity rhythms in golden hamsters.J. Comp. Physiol. 153, 123–132 (1983). https://doi.org/10.1007/BF00610349

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