The relationship between phase and period responses to light pulses

Stokes, Mark, Kent, Stephen and Armstrong, Stuart Maxwell 2002, The relationship between phase and period responses to light pulses, Biological rhythm research, vol. 33, no. 3, pp. 303-317, doi: 10.1076/brhm.33.3.303.8265.

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Title The relationship between phase and period responses to light pulses
Author(s) Stokes, MarkORCID iD for Stokes, Mark
Kent, Stephen
Armstrong, Stuart Maxwell
Journal name Biological rhythm research
Volume number 33
Issue number 3
Start page 303
End page 317
Publisher Swets and Zeitlinger BV
Place of publication Lisse, Netherlands
Publication date 2002-07
ISSN 0929-1016
Summary Current theories of stable circadian entrainment postulate phase delays should be associated with period lengthening, while phase advances should be associated with period shortening. While characterising features of the rat PRC to light, we noted substantial numbers of responses that displayed the opposite pattern. Forty-eight rats provided data for 192 phase responses. Limiting our analysis to phase shifts greater than 1 hour, we found 44 displayed the expected predicted relationship, and 33 displayed the contrary paradoxical relationship. Paradoxical responders possessed significantly shorter initial activity periods, compared to predicted responders. Activity was significantly lengthened by paradoxical responders and shortened by predicted responders following light pulse exposure. These results suggest a second mode of stable entrainment. Additionally, these results indicate entrainment mode, predicted or paradoxical, is based upon activity period duration. Short activity period durations will be associated with paradoxical responses, long durations will be associated with predicted responses. We argue that, given the dynamic changes in photoperiod, both modes of entrainment are necessary to provide stable entrainment across the year.
Language eng
DOI 10.1076/brhm.33.3.303.8265
Field of Research 170101 Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology)
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ┬ęSwets and Zeitlinger
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Document type: Journal Article
Collections: Faculty of Health
School of Psychology
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