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The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN)

Electrophysiological responses of SCN neurons to light steps are well established, but responses to more natural modulations in irradiance have been much less studied. We address this deficit first by showing that variations in irradiance for human subjects are biased towards low temporal frequencie...

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Autores principales: Dobb, Rachel, Martial, Franck, Elijah, Daniel, Storchi, Riccardo, Brown, Timothy M., Lucas, Robert J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5585163/
https://www.ncbi.nlm.nih.gov/pubmed/28874778
http://dx.doi.org/10.1038/s41598-017-11184-2
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author Dobb, Rachel
Martial, Franck
Elijah, Daniel
Storchi, Riccardo
Brown, Timothy M.
Lucas, Robert J.
author_facet Dobb, Rachel
Martial, Franck
Elijah, Daniel
Storchi, Riccardo
Brown, Timothy M.
Lucas, Robert J.
author_sort Dobb, Rachel
collection PubMed
description Electrophysiological responses of SCN neurons to light steps are well established, but responses to more natural modulations in irradiance have been much less studied. We address this deficit first by showing that variations in irradiance for human subjects are biased towards low temporal frequencies and small magnitudes. Using extracellular recordings we show that neurons in the mouse SCN are responsive to stimuli with these characteristics, tracking sinusoidal modulations in irradiance best at lower temporal frequencies and responding to abrupt changes in irradiance over a range of commonly encountered contrasts. The spectral sensitivity of these light adapted responses indicates that they are driven primarily by cones, but with melanopsin (and/or rods) contributing under more gradual changes. Higher frequency modulations in irradiance increased time averaged firing of SCN neurons (typically considered to encode background light intensity) modestly over that encountered during steady exposure, but did not have a detectable effect on the circadian phase resetting efficiency of light. Our findings highlight the SCN’s ability to encode naturalistic temporal modulations in irradiance, while revealing that the circadian system can effectively integrate such signals over time such that phase-resetting responses remain proportional to the mean light exposure.
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spelling pubmed-55851632017-09-06 The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN) Dobb, Rachel Martial, Franck Elijah, Daniel Storchi, Riccardo Brown, Timothy M. Lucas, Robert J. Sci Rep Article Electrophysiological responses of SCN neurons to light steps are well established, but responses to more natural modulations in irradiance have been much less studied. We address this deficit first by showing that variations in irradiance for human subjects are biased towards low temporal frequencies and small magnitudes. Using extracellular recordings we show that neurons in the mouse SCN are responsive to stimuli with these characteristics, tracking sinusoidal modulations in irradiance best at lower temporal frequencies and responding to abrupt changes in irradiance over a range of commonly encountered contrasts. The spectral sensitivity of these light adapted responses indicates that they are driven primarily by cones, but with melanopsin (and/or rods) contributing under more gradual changes. Higher frequency modulations in irradiance increased time averaged firing of SCN neurons (typically considered to encode background light intensity) modestly over that encountered during steady exposure, but did not have a detectable effect on the circadian phase resetting efficiency of light. Our findings highlight the SCN’s ability to encode naturalistic temporal modulations in irradiance, while revealing that the circadian system can effectively integrate such signals over time such that phase-resetting responses remain proportional to the mean light exposure. Nature Publishing Group UK 2017-09-05 /pmc/articles/PMC5585163/ /pubmed/28874778 http://dx.doi.org/10.1038/s41598-017-11184-2 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Dobb, Rachel
Martial, Franck
Elijah, Daniel
Storchi, Riccardo
Brown, Timothy M.
Lucas, Robert J.
The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN)
title The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN)
title_full The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN)
title_fullStr The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN)
title_full_unstemmed The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN)
title_short The impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (SCN)
title_sort impact of temporal modulations in irradiance under light adapted conditions on the mouse suprachiasmatic nuclei (scn)
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5585163/
https://www.ncbi.nlm.nih.gov/pubmed/28874778
http://dx.doi.org/10.1038/s41598-017-11184-2
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