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Mutti DO, Mulvihill SP, Orr DJ, Shorter PD, Hartwick ATE. The Effect of Refractive Error on Melanopsin-Driven Pupillary Responses. Invest Ophthalmol Vis Sci 2020; 61:22. [PMID: 33091116 PMCID: PMC7594593 DOI: 10.1167/iovs.61.12.22] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Human and animal studies suggest that light-mediated dopamine release may underlie the protective effect of time outdoors on myopia development. Melanopsin-containing retinal ganglion cells may be involved in this process by integrating ambient light exposure and regulating retinal dopamine levels. The study evaluates this potential involvement by examining whether melanopsin-driven pupillary responses are associated with adult refractive error. Methods Subjects were 45 young adults (73% female, 24.1 ± 1.8 years) with refractive errors ranging from –6.33 D to +1.70 D. The RAPDx (Konan Medical) pupillometer measured normalized pupillary responses to three forms of square-wave light pulses alternating with darkness at 0.1 Hz: alternating long wavelength (red, peak at 608 nm) and short wavelength (blue, peak at 448 nm), followed by red only and then blue only. Results Non-myopic subjects displayed greater pupillary constriction in the blue-only condition and slower redilation following blue light offset than subjects with myopia (P = 0.011). Pupillary responses were not significantly different between myopic and non-myopic subjects in the red-only condition (P = 0.15). More hyperopic/less myopic refractive error as a continuous variable was linearly related to larger increases in pupillary constriction in response to blue-only stimuli (r = 0.48, P = 0.001). Conclusions Repeated light exposures to blue test stimuli resulted in an adaptation in the pupillary response (more constriction and slower redilation), presumably due to increased melanopsin-mediated input in more hyperopic/less myopic adults. This adaptive property supports a possible role for these ganglion cells in the protective effects of time outdoors on myopia development.
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Affiliation(s)
- Donald O Mutti
- The Ohio State University College of Optometry, Columbus, Ohio, United States
| | | | - Danielle J Orr
- The Ohio State University College of Optometry, Columbus, Ohio, United States
| | - Patrick D Shorter
- Optical Radiation Bioeffects Branch, Tri-Service Research Laboratory, Fort Sam Houston, Texas, United States
| | - Andrew T E Hartwick
- The Ohio State University College of Optometry, Columbus, Ohio, United States
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2
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Spitschan M, Woelders T. The Method of Silent Substitution for Examining Melanopsin Contributions to Pupil Control. Front Neurol 2018; 9:941. [PMID: 30538662 PMCID: PMC6277556 DOI: 10.3389/fneur.2018.00941] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 10/17/2018] [Indexed: 01/23/2023] Open
Abstract
The human pupillary light response is driven by all classes of photoreceptors in the human eye-the three classes of cones, the rods, and the intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin. These photoreceptor classes have distinct but overlapping spectral tuning, and even a monochromatic light with a wavelength matched to the peak spectral sensitivity of a given photoreceptor will stimulate all photoreceptors. The method of silent substitution uses pairs of lights ("metamers") to selectively stimulate a given class of photoreceptors while keeping the activation of all others constant. In this primer, we describe the method of silent substitution and provide an overview of studies that have used it to examine inputs to the human pupillary light response.
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Affiliation(s)
- Manuel Spitschan
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Tom Woelders
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
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3
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Lei S, Goltz HC, Sklar JC, Wong AMF. The absence of attenuating effect of red light exposure on pre-existing melanopsin-driven post-illumination pupil response. Vision Res 2016; 124:59-65. [PMID: 27371765 DOI: 10.1016/j.visres.2016.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/01/2016] [Accepted: 06/02/2016] [Indexed: 11/18/2022]
Abstract
It has been proposed that after activation by blue light, activated melanopsin is converted back to its resting state by long wavelength red light exposure, a putative mechanism of melanopsin chromophore recovery in vivo. We tested this hypothesis by investigating whether red light attenuates the ongoing post-illumination pupil response (PIPR) induced by melanopsin-activating blue light. Pupillary light responses were tested using "Blue+Red" double flashes and "Blue Only" single flash stimuli in 10 visually normal subjects. For "Blue+Red" conditions, PIPR was induced with an intense blue flash, followed by experimental red light exposure of variable intensity and duration (Experiment 1) immediately or 9s after the offset of the blue flash (Experiment 2). For "Blue Only" conditions, only the PIPR-inducing blue stimuli were presented (reference condition). PIPR was defined as the mean pupil size from 10 to 30s (Experiment 1) and from 25 to 60s (Experiment 2) after the offset of blue light stimuli. The results showed that PIPR from "Blue+Red" conditions did not differ significantly from those of "Blue Only" conditions (p=0.55) in Experiment 1. The two stimulation conditions also did not differ in Experiment 2 (p=0.38). We therefore conclude that red light exposure does not alter the time course of PIPR induced by blue light. This finding does not support the hypothesis that long wavelength red light reverses activated melanopsin; rather it lends support to the hypothesis that the wavelengths of stimuli driving both the forward and backward reactions of melanopsin may be similar.
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Affiliation(s)
- Shaobo Lei
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada
| | - Herbert C Goltz
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada; Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
| | - Jaime C Sklar
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada
| | - Agnes M F Wong
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Canada; Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada; Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada.
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4
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Walch OJ, Zhang LS, Reifler AN, Dolikian ME, Forger DB, Wong KY. Characterizing and modeling the intrinsic light response of rat ganglion-cell photoreceptors. J Neurophysiol 2015; 114:2955-66. [PMID: 26400257 PMCID: PMC4737408 DOI: 10.1152/jn.00544.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/18/2015] [Indexed: 12/20/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) mediate both image-forming vision and non-image-forming visual responses such as pupillary constriction and circadian photoentrainment. Five types of ipRGCs, named M1-M5, have been discovered in rodents. To further investigate their photoresponse properties, we made multielectrode array spike recordings from rat ipRGCs, classified them into M1, M2/M4, and M3/M5 clusters, and measured their intrinsic, melanopsin-based responses to single and flickering light pulses. Results showed that ipRGC spiking can track flickers up to ∼0.2 Hz in frequency and that flicker intervals between 5 and 14 s evoke the most spikes. We also learned that melanopsin's integration time is intensity and cluster dependent. Using these data, we constructed a mathematical model for each cluster's intrinsic photoresponse. We found that the data for the M1 cluster are best fit by a model that assumes a large photoresponse, causing the cell to enter depolarization block. Our models also led us to hypothesize that the M2/M4 and M3/M5 clusters experience comparable photoexcitation but that the M3/M5 cascade decays significantly faster than the M2/M4 cascade, resulting in different response waveforms between these clusters. These mathematical models will help predict how each ipRGC cluster might respond to stimuli of any waveform and could inform the invention of lighting technologies that promote health through melanopsin stimulation.
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Affiliation(s)
- Olivia J Walch
- Department of Mathematics, University of Michigan, Ann Arbor, Michigan
| | - L Samantha Zhang
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Aaron N Reifler
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Michael E Dolikian
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan
| | - Daniel B Forger
- Department of Mathematics, University of Michigan, Ann Arbor, Michigan; Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, Michigan; and
| | - Kwoon Y Wong
- Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan; Department of Molecular, Cellular & Developmental Biology, University of Michigan, Ann Arbor, Michigan
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5
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Zabiliūtė A, Vaicekauskas R, Vitta P, Zukauskas A. Phosphor-converted LEDs with low circadian action for outdoor lighting. OPTICS LETTERS 2014; 39:563-566. [PMID: 24487866 DOI: 10.1364/ol.39.000563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Dichromatic phosphor-converted (pc) light-emitting diodes (LEDs) with low circadian action are proposed for low-luminance photobiologically safe outdoor illumination. The LEDs feature the partial conversion of blue radiation in an orange phosphor with the resulting correlated color temperature in the "firelight" range of 1700-2500 K. The circadian action factor, which is the ratio of the biological efficacy of radiation due to the excitation of intrinsically photosensitive retinal ganglion cells to the mesopic luminous efficacy of radiation, is considerably lower than that of commercial white pc LEDs. The equivalent general color-rendering index estimated with regard to the reduced color-discrimination ability of human vision at low luminances has appropriate values in between those of common white pc LEDs and high-pressure sodium lamp.
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Lucas RJ, Peirson SN, Berson DM, Brown TM, Cooper HM, Czeisler CA, Figueiro MG, Gamlin PD, Lockley SW, O'Hagan JB, Price LLA, Provencio I, Skene DJ, Brainard GC. Measuring and using light in the melanopsin age. Trends Neurosci 2014; 37:1-9. [PMID: 24287308 PMCID: PMC4699304 DOI: 10.1016/j.tins.2013.10.004] [Citation(s) in RCA: 491] [Impact Index Per Article: 49.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 01/17/2023]
Abstract
Light is a potent stimulus for regulating circadian, hormonal, and behavioral systems. In addition, light therapy is effective for certain affective disorders, sleep problems, and circadian rhythm disruption. These biological and behavioral effects of light are influenced by a distinct photoreceptor in the eye, melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), in addition to conventional rods and cones. We summarize the neurophysiology of this newly described sensory pathway and consider implications for the measurement, production, and application of light. A new light-measurement strategy taking account of the complex photoreceptive inputs to these non-visual responses is proposed for use by researchers, and simple suggestions for artificial/architectural lighting are provided for regulatory authorities, lighting manufacturers, designers, and engineers.
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Affiliation(s)
- Robert J Lucas
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
| | - Stuart N Peirson
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, UK
| | - David M Berson
- Department of Neuroscience, Brown University, Box G-LN, Providence, RI, USA
| | - Timothy M Brown
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Howard M Cooper
- INSERM 846 Stem Cell and Brain Research Institute, Department of Chronobiology, 18 Avenue du Doyen Lépine, 69500 Bron, France
| | - Charles A Czeisler
- Division of Sleep Medicine, Harvard Medical School, and Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Mariana G Figueiro
- Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Paul D Gamlin
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Steven W Lockley
- Division of Sleep Medicine, Harvard Medical School, and Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | | | | | - Ignacio Provencio
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Debra J Skene
- Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - George C Brainard
- Department of Neurology, Thomas Jefferson University, Philidelphia, PA, USA.
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7
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Roecklein K, Wong P, Ernecoff N, Miller M, Donofry S, Kamarck M, Wood-Vasey WM, Franzen P. The post illumination pupil response is reduced in seasonal affective disorder. Psychiatry Res 2013; 210:150-8. [PMID: 23809464 PMCID: PMC3795919 DOI: 10.1016/j.psychres.2013.05.023] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 05/15/2013] [Accepted: 05/19/2013] [Indexed: 10/26/2022]
Abstract
Individuals with seasonal affective disorder (SAD) may have a decreased retinal sensitivity in the non-image forming light-input pathway. We examined the post illumination pupil response (PIPR) among individuals with SAD and healthy controls to identify possible differences in the melanopsin signaling pathway. We also investigated whether melanopsin gene (OPN4) variations would predict variability in the PIPR. Fifteen SAD and 15 control participants (80% women, mean age 36.7 years, S.D.=14.5) were assessed in the fall/winter. Participants were diagnosed based on DSM-IV-TR criteria. Infrared pupillometry was used to measure pupil diameter prior to, during, and after red and blue stimuli. In response to blue light, the SAD group had a reduced PIPR and a lower PIPR percent change relative to controls. The PIPR after the blue stimulus also varied on the basis of OPN4 I394T genotype, but not OPN4 P10L genotype. These findings may indicate that individuals with SAD have a less sensitive light input pathway as measured by the PIPR, leading to differences in neurobiological and behavioral responses such as alertness, circadian photoentrainment, and melatonin release. In addition, this sensitivity may vary based on sequence variations in OPN4, although a larger sample and replication is needed.
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Affiliation(s)
- Kathryn Roecklein
- Department of Psychology, University of Pittsburgh, 201S Bouquet St, Pittsburgh, PA 15260, USA.
| | - Patricia Wong
- Department of Psychology, University of Pittsburgh, 201 S Bouquet St, Pittsburgh, PA 15260, USA
| | - Natalie Ernecoff
- Department of Psychology, University of Pittsburgh, 201 S Bouquet St, Pittsburgh, PA 15260, USA
| | - Megan Miller
- Department of Psychology, University of Pittsburgh, 201 S Bouquet St, Pittsburgh, PA 15260, USA
| | - Shannon Donofry
- Department of Psychology, University of Pittsburgh, 201 S Bouquet St, Pittsburgh, PA 15260, USA
| | - Marissa Kamarck
- Department of Psychology, University of Pittsburgh, 201 S Bouquet St, Pittsburgh, PA 15260, USA
| | | | - Peter Franzen
- Department of Psychiatry, University of Pittsburgh Medical Center, Pittsburgh PA, USA
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8
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Brown TM, Allen AE, al-Enezi J, Wynne J, Schlangen L, Hommes V, Lucas RJ. The melanopic sensitivity function accounts for melanopsin-driven responses in mice under diverse lighting conditions. PLoS One 2013; 8:e53583. [PMID: 23301090 PMCID: PMC3536742 DOI: 10.1371/journal.pone.0053583] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 12/03/2012] [Indexed: 12/19/2022] Open
Abstract
In addition to rods and cones, photoreception in mammals extends to a third retinal cell type expressing the photopigment melanopsin. The influences of this novel opsin are widespread, ranging from pupillary and circadian responses to brightness perception, yet established approaches to quantifying the biological effects of light do not adequately account for melanopsin sensitivity. We have recently proposed a novel metric, the melanopic sensitivity function (V(Z)λ), to address this deficiency. Here, we further validate this new measure with a variety of tests based on potential barriers to its applicability identified in the literature or relating to obvious practical benefits. Using electrophysiogical approaches and pupillometry, initially in rodless+coneless mice, our data demonstrate that under a very wide range of different conditions (including switching between stimuli with highly divergent spectral content) the V(Z)λ function provides an accurate prediction of the sensitivity of melanopsin-dependent responses. We further show that V(Z)λ provides the best available description of the spectral sensitivity of at least one aspect of the visual response in mice with functional rods and cones: tonic firing activity in the lateral geniculate nuclei. Together, these data establish V(Z)λ as an important new approach for light measurement with widespread practical utility.
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Affiliation(s)
- Timothy M. Brown
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Annette E. Allen
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Jazi al-Enezi
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Jonathan Wynne
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | | | - Vanja Hommes
- Philips Consumer Lifestyle, Drachten, The Netherlands
| | - Robert J. Lucas
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail:
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9
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Roecklein KA, Wong PM, Miller MA, Donofry SD, Kamarck ML, Brainard GC. Melanopsin, photosensitive ganglion cells, and seasonal affective disorder. Neurosci Biobehav Rev 2012; 37:229-39. [PMID: 23286902 DOI: 10.1016/j.neubiorev.2012.12.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 11/05/2012] [Accepted: 12/21/2012] [Indexed: 02/05/2023]
Abstract
In two recent reports, melanopsin gene variations were associated with seasonal affective disorder (SAD), and in changes in the timing of sleep and activity in healthy individuals. New studies have deepened our understanding of the retinohypothalamic tract, which translates environmental light received by the retina into neural signals sent to a set of nonvisual nuclei in the brain that are responsible for functions other than sight including circadian, neuroendocrine and neurobehavioral regulation. Because this pathway mediates seasonal changes in physiology, behavior, and mood, individual variations in the pathway may explain why approximately 1-2% of the North American population develops mood disorders with a seasonal pattern (i.e., Major Depressive and Bipolar Disorders with a seasonal pattern, also known as seasonal affective disorder/SAD). Components of depression including mood changes, sleep patterns, appetite, and cognitive performance can be affected by the biological and behavioral responses to light. Specifically, variations in the gene sequence for the retinal photopigment, melanopsin, may be responsible for significant increased risk for mood disorders with a seasonal pattern, and may do so by leading to changes in activity and sleep timing in winter. The retinal sensitivity of SAD is hypothesized to be decreased compared to controls, and that further decrements in winter light levels may combine to trigger depression in winter. Here we outline steps for new research to address the possible role of melanopsin in seasonal affective disorder including chromatic pupillometry designed to measure the sensitivity of melanopsin containing retinal ganglion cells.
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Affiliation(s)
- Kathryn A Roecklein
- Department of Psychology, University of Pittsburgh, 3500 Sennott Square, 210 South Bouquet St., Pittsburgh, PA 15260, USA.
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10
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Provencio I, Warthen DM. Melanopsin, the photopigment of intrinsically photosensitive retinal ganglion cells. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/wmts.29] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Enezi JA, Revell V, Brown T, Wynne J, Schlangen L, Lucas R. A "melanopic" spectral efficiency function predicts the sensitivity of melanopsin photoreceptors to polychromatic lights. J Biol Rhythms 2011; 26:314-23. [PMID: 21775290 DOI: 10.1177/0748730411409719] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Photoreception in the mammalian retina is not restricted to rods and cones but extends to a small number of intrinsically photosensitive retinal ganglion cells expressing the photopigment melanopsin. These mRGCs are especially important contributors to circadian entrainment, the pupil light reflex, and other so-called nonimage-forming (NIF) responses. The spectral sensitivity of melanopsin phototransduction has been addressed in several species by comparing responses to a range of monochromatic stimuli. The resultant action spectra match the predicted profile of an opsin:vitamin A-based photopigment (nomogram) with a peak sensitivity (λ(max)) around 480 nm. It would be most useful to be able to use this spectral sensitivity function to predict melanopsin's sensitivity to broad-spectrum, including "white," lights. However, evidence that melanopsin is a bistable pigment with an intrinsic light-dependent bleach recovery mechanism raises the possibility of a more complex relationship between spectral quality and photoreceptor response. Here, we set out to empirically determine whether simply weighting optical power at each wavelength according to the 480-nm nomogram and integrating across the spectrum could predict melanopsin sensitivity to a variety of polychromatic stimuli. We show that pupillomotor and circadian responses of mice relying solely on melanopsin for their photosensitivity (rd/rd cl) can indeed be accurately predicted using this methodology. Our data therefore suggest that the 480-nm nomogram may be employed as the basis for a new photometric measure of light intensity (which we term "melanopic") relevant for melanopsin photoreception. They further show that measuring light in these terms predicts the melanopsin response to light of divergent spectral composition much more reliably than other methods for quantifying irradiance or illuminance currently in widespread use.
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Affiliation(s)
- Jazi al Enezi
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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12
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Lall GS, Revell VL, Momiji H, Al Enezi J, Altimus CM, Güler AD, Aguilar C, Cameron MA, Allender S, Hankins MW, Lucas RJ. Distinct contributions of rod, cone, and melanopsin photoreceptors to encoding irradiance. Neuron 2010; 66:417-28. [PMID: 20471354 PMCID: PMC2875410 DOI: 10.1016/j.neuron.2010.04.037] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2010] [Indexed: 12/04/2022]
Abstract
Photoreceptive, melanopsin-expressing retinal ganglion cells (mRGCs) encode ambient light (irradiance) for the circadian clock, the pupillomotor system, and other influential behavioral/physiological responses. mRGCs are activated both by their intrinsic phototransduction cascade and by the rods and cones. However, the individual contribution of each photoreceptor class to irradiance responses remains unclear. We address this deficit using mice expressing human red cone opsin, in which rod-, cone-, and melanopsin-dependent responses can be identified by their distinct spectral sensitivity. Our data reveal an unexpectedly important role for rods. These photoreceptors define circadian responses at very dim “scotopic” light levels but also at irradiances at which pattern vision relies heavily on cones. By contrast, cone input to irradiance responses dissipates following light adaptation to the extent that these receptors make a very limited contribution to circadian and pupillary light responses under these conditions. Our data provide new insight into retinal circuitry upstream of mRGCs and optimal stimuli for eliciting irradiance responses.
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Affiliation(s)
- Gurprit S Lall
- Faculty of Life Sciences, AV Hill Building, University of Manchester, Manchester M13 9PT, UK
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Mure LS, Cornut PL, Rieux C, Drouyer E, Denis P, Gronfier C, Cooper HM. Melanopsin bistability: a fly's eye technology in the human retina. PLoS One 2009; 4:e5991. [PMID: 19551136 PMCID: PMC2695781 DOI: 10.1371/journal.pone.0005991] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 05/06/2009] [Indexed: 11/18/2022] Open
Abstract
In addition to rods and cones, the human retina contains light-sensitive ganglion cells that express melanopsin, a photopigment with signal transduction mechanisms similar to that of invertebrate rhabdomeric photopigments (IRP). Like fly rhodopsins, melanopsin acts as a dual-state photosensitive flip-flop in which light drives both phototransduction responses and chromophore photoregeneration that bestows independence from the retinoid cycle required by rods and cones to regenerate photoresponsiveness following bleaching by light. To explore the hypothesis that melanopsin in humans expresses the properties of a bistable photopigment in vivo we used the pupillary light reflex (PLR) as a tool but with methods designed to study invertebrate photoreceptors. We show that the pupil only attains a fully stabilized state of constriction after several minutes of light exposure, a feature that is consistent with typical IRP photoequilibrium spectra. We further demonstrate that previous exposure to long wavelength light increases, while short wavelength light decreases the amplitude of pupil constriction, a fundamental property of IRP difference spectra. Modelling these responses to invertebrate photopigment templates yields two putative spectra for the underlying R and M photopigment states with peaks at 481 nm and 587 nm respectively. Furthermore, this bistable mechanism may confer a novel form of "photic memory" since information of prior light conditions is retained and shapes subsequent responses to light. These results suggest that the human retina exploits fly-like photoreceptive mechanisms that are potentially important for the modulation of non-visual responses to light and highlights the ubiquitous nature of photoswitchable photosensors across living organisms.
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Affiliation(s)
- Ludovic S. Mure
- Department of Chronobiology, INSERM, U846, Stem Cell and Brain Research Institute, Bron, France
- University of Lyon, Lyon I, UMR-S 846, Lyon, France
| | - Pierre-Loic Cornut
- Department of Chronobiology, INSERM, U846, Stem Cell and Brain Research Institute, Bron, France
- University of Lyon, Lyon I, UMR-S 846, Lyon, France
- Department of Ophthalmology, CHU de Lyon Hopital Edouard Herriot, Lyon, France
| | - Camille Rieux
- Department of Chronobiology, INSERM, U846, Stem Cell and Brain Research Institute, Bron, France
- University of Lyon, Lyon I, UMR-S 846, Lyon, France
| | - Elise Drouyer
- Department of Chronobiology, INSERM, U846, Stem Cell and Brain Research Institute, Bron, France
- University of Lyon, Lyon I, UMR-S 846, Lyon, France
| | - Philippe Denis
- Department of Chronobiology, INSERM, U846, Stem Cell and Brain Research Institute, Bron, France
- University of Lyon, Lyon I, UMR-S 846, Lyon, France
- Department of Ophthalmology, CHU de Lyon Hopital Edouard Herriot, Lyon, France
| | - Claude Gronfier
- Department of Chronobiology, INSERM, U846, Stem Cell and Brain Research Institute, Bron, France
- University of Lyon, Lyon I, UMR-S 846, Lyon, France
| | - Howard M. Cooper
- Department of Chronobiology, INSERM, U846, Stem Cell and Brain Research Institute, Bron, France
- University of Lyon, Lyon I, UMR-S 846, Lyon, France
- * E-mail:
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Brainard GC, Sliney D, Hanifin JP, Glickman G, Byrne B, Greeson JM, Jasser S, Gerner E, Rollag MD. Sensitivity of the human circadian system to short-wavelength (420-nm) light. J Biol Rhythms 2008; 23:379-86. [PMID: 18838601 DOI: 10.1177/0748730408323089] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The circadian and neurobehavioral effects of light are primarily mediated by a retinal ganglion cell photoreceptor in the mammalian eye containing the photopigment melanopsin. Nine action spectrum studies using rodents, monkeys, and humans for these responses indicate peak sensitivities in the blue region of the visible spectrum ranging from 459 to 484 nm, with some disagreement in short-wavelength sensitivity of the spectrum. The aim of this work was to quantify the sensitivity of human volunteers to monochromatic 420-nm light for plasma melatonin suppression. Adult female (n=14) and male (n=12) subjects participated in 2 studies, each employing a within-subjects design. In a fluence-response study, subjects (n=8) were tested with 8 light irradiances at 420 nm ranging over a 4-log unit photon density range of 10(10) to 10(14) photons/cm(2)/sec and 1 dark exposure control night. In the other study, subjects (n=18) completed an experiment comparing melatonin suppression with equal photon doses (1.21 x 10(13) photons/cm(2)/sec) of 420 nm and 460 nm monochromatic light and a dark exposure control night. The first study demonstrated a clear fluence-response relationship between 420-nm light and melatonin suppression (p<0.001) with a half-saturation constant of 2.74 x 10(11) photons/cm(2)/sec. The second study showed that 460-nm light is significantly stronger than 420-nm light for suppressing melatonin (p<0.04). Together, the results clarify the visible short-wavelength sensitivity of the human melatonin suppression action spectrum. This basic physiological finding may be useful for optimizing lighting for therapeutic and other applications.
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Affiliation(s)
- George C Brainard
- Department of Neurology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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