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The effect of repeated pulses of light at the same time on period responses of the rat circadian pacemaker.
journal contribution
posted on 2001-03-01, 00:00 authored by Mark StokesMark Stokes, S Kent, S ArmstrongA consequence of simple velocity-based models is that, in response to light pulses, the circadian period should adjust inversely to phase. In addition, because of the interaction of circadian period and phase response, earlier circadian period changes should modify later circadian period changes. The literature contains few mentions of response curves of circadian period responses following light pulses. Rats were exposed to four pulses of light (60 minutes, 1000 lux) at the same circadian time, a minimum of 26 days apart; we assessed period responses and possible bias in the period-response curve. Modulation of circadian period following light-induced phase responses was examined by assessing the period of running wheel activity onset. Phase and circadian period were not consistently found to share an inverse relationship. Moreover, biases in initial period tended to be increased by the experimental protocol regardless of circadian time of pulse. Rats with a short initial (highvelocity) period had a lengthened period, while rats with a long initial period (low velocity) tended to have a reduce period. However, rats with a long initial period were phase delay biased, not phase advance biased. These results do not support a simple velocity model of the pacemaker.
History
Journal
Chronobiology internationalVolume
18Issue
2Pagination
187 - 201Publisher
Pergamon PressLocation
Oxford, EnglandPublisher DOI
ISSN
0742-0528eISSN
1525-6073Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2001, by Marcel Dekker, Inc.Usage metrics
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Science & TechnologyLife Sciences & BiomedicineBiologyPhysiologyLife Sciences & Biomedicine - Other Topicscircadian rhythmslight pulsesmultiple light pulsesperiod responsesphase response curvesRUNNING-WHEEL ACTIVITYFUNCTIONAL-ANALYSISNOCTURNAL RODENTSPHASE-RESPONSEDJUNGARIAN HAMSTERSACTIVITY RHYTHMSSYRIAN-HAMSTERENTRAINMENTCLOCKFREQUENCY
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