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Author (up) Foster, R.G.; Hughes, S.; Peirson, S.N. url  doi
openurl 
  Title Circadian Photoentrainment in Mice and Humans Type Journal Article
  Year 2020 Publication Biology Abbreviated Journal Biology (Basel)  
  Volume 9 Issue 7 Pages  
  Keywords Review; Animals; Human Health; circadian; entrainment; human; melanopsin (OPN4); mouse; photoreceptor  
  Abstract Light around twilight provides the primary entrainment signal for circadian rhythms. Here we review the mechanisms and responses of the mouse and human circadian systems to light. Both utilize a network of photosensitive retinal ganglion cells (pRGCs) expressing the photopigment melanopsin (OPN4). In both species action spectra and functional expression of OPN4 in vitro show that melanopsin has a lambdamax close to 480 nm. Anatomical findings demonstrate that there are multiple pRGC sub-types, with some evidence in mice, but little in humans, regarding their roles in regulating physiology and behavior. Studies in mice, non-human primates and humans, show that rods and cones project to and can modulate the light responses of pRGCs. Such an integration of signals enables the rods to detect dim light, the cones to detect higher light intensities and the integration of intermittent light exposure, whilst melanopsin measures bright light over extended periods of time. Although photoreceptor mechanisms are similar, sensitivity thresholds differ markedly between mice and humans. Mice can entrain to light at approximately 1 lux for a few minutes, whilst humans require light at high irradiance (>100's lux) and of a long duration (>30 min). The basis for this difference remains unclear. As our retinal light exposure is highly dynamic, and because photoreceptor interactions are complex and difficult to model, attempts to develop evidence-based lighting to enhance human circadian entrainment are very challenging. A way forward will be to define human circadian responses to artificial and natural light in the “real world” where light intensity, duration, spectral quality, time of day, light history and age can each be assessed.  
  Address Sleep & Circadian Neuroscience Institute (SCNi), Nuffield Department of Clinical Neurosciences, Sir William Dunn School of Pathology, Oxford Molecular Pathology Institute, South Parks Road, University of Oxford, Oxford OX1 3RF, UK  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2079-7737 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:32708259; PMCID:PMC7408241 Approved no  
  Call Number GFZ @ kyba @ Serial 3082  
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