HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 286/3/R539    most recent 00456.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Evans, J. A. Articles by Gorman, M. R. Search for Related Content PubMed PubMed Citation Articles by Evans, J. A. Articles by Gorman, M. R.

COMPLEX FUNCTION OF THE CENTRAL NERVOUS SYSTEM, SLEEP AND LOCOMOTION

Photoperiod differentially modulates photic and nonphotic phase response curves of hamsters

Departments of ¹Psychology and ²Psychiatry, University of California, San Diego, La Jolla, California 92093

Submitted 12 August 2003 ; accepted in final form 21 November 2003

Circadian pacemakers respond to light pulses with phase adjustments that allow for daily synchronization to 24-h light-dark cycles. In Syrian hamsters, Mesocricetus auratus, light-induced phase shifts are larger after entrainment to short daylengths (e.g., 10 h light:14 h dark) vs. long daylengths (e.g., 14 h light:10 h dark). The present study assessed whether photoperiodic modulation of phase resetting magnitude extends to nonphotic perturbations of the circadian rhythm and, if so, whether the relationship parallels that of photic responses. Male Syrian hamsters, entrained for 31 days to either short or long daylengths, were transferred to novel wheel running cages for 2 h at times spanning the entire circadian cycle. Phase shifts induced by this stimulus varied with the circadian time of exposure, but the amplitude of the resulting phase response curve was not markedly influenced by photoperiod. Previously reported photoperiodic effects on photic phase resetting were verified under the current paradigm using 15-min light pulses. Photoperiodic modulation of phase resetting magnitude is input specific and may reflect alterations in the transmission of photic stimuli.

circadian rhythm; novel wheel running; free running period; tau response curve; pacemaker amplitude

This article has been cited by other articles:

				B. J. Prendergast and L. M. Pyter Photoperiod History Differentially Impacts Reproduction and Immune Function in Adult Siberian Hamsters J Biol Rhythms, December 1, 2009; 24(6): 509 - 522. [Abstract] [PDF]

				J. B. Zawilska, A. Lorenc, M. Berezinska, B. Vivien-Roels, P. Pevet, and D. J. Skene Photoperiod-Dependent Changes in Melatonin Synthesis in the Turkey Pineal Gland and Retina Poult. Sci., July 1, 2007; 86(7): 1397 - 1405. [Abstract] [Full Text] [PDF]