8 results
Melanopsin Vision
- Sensation and Perception Through Intrinsically Photosensitive Retinal Ganglion Cells
- Daniel S. Joyce, Kevin W. Houser, Stuart N. Peirson, Jamie M. Zeitzer, Andrew J. Zele
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- Published online:
- 15 December 2022
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- 19 January 2023
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Intrinsically photosensitive retinal ganglion cells (ipRGCs) are the most recently discovered photoreceptor class in the human retina. This Element integrates new knowledge and perspectives from visual neuroscience, psychology, sleep science and architecture to discuss how melanopsin-mediated ipRGC functions can be measured and their circuits manipulated. It reveals contemporary and emerging lighting technologies as powerful tools to set mind, brain and behaviour.
Structure and function of the gap junctional network of photoreceptive ganglion cells
- Xiwu Zhao, Kwoon Y. Wong
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- Journal:
- Visual Neuroscience / Volume 38 / 2021
- Published online by Cambridge University Press:
- 16 September 2021, E014
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Intrinsically photosensitive retinal ganglion cells (ipRGCs) signal not only anterogradely to drive behavioral responses, but also retrogradely to some amacrine interneurons to modulate retinal physiology. We previously found that all displaced amacrine cells with spiking, tonic excitatory photoresponses receive gap-junction input from ipRGCs, but the connectivity patterns and functional roles of ipRGC-amacrine coupling remained largely unknown. Here, we injected PoPro1 fluorescent tracer into all six types of mouse ipRGCs to identify coupled amacrine cells, and analyzed the latter’s morphological and electrophysiological properties. We also examined how genetically disrupting ipRGC-amacrine coupling affected ipRGC photoresponses. Results showed that ipRGCs couple with not just ON- and ON/OFF-stratified amacrine cells in the ganglion-cell layer as previously reported, but also OFF-stratified amacrine cells in both ganglion-cell and inner nuclear layers. M1- and M3-type ipRGCs couple mainly with ON/OFF-stratified amacrine cells, whereas the other ipRGC types couple almost exclusively with ON-stratified ones. ipRGCs transmit melanopsin-based light responses to at least 93% of the coupled amacrine cells. Some of the ON-stratifying ipRGC-coupled amacrine cells exhibit transient hyperpolarizing light responses. We detected bidirectional electrical transmission between an ipRGC and a coupled amacrine cell, although transmission was asymmetric for this particular cell pair, favoring the ipRGC-to-amacrine direction. We also observed electrical transmission between two amacrine cells coupled to the same ipRGC. In both scenarios of coupling, the coupled cells often spiked synchronously. While ipRGC-amacrine coupling somewhat reduces the peak firing rates of ipRGCs’ intrinsic melanopsin-based photoresponses, it renders these responses more sustained and longer-lasting. In summary, ipRGCs’ gap junctional network involves more amacrine cell types and plays more roles than previously appreciated.
The retinal pigments of the whale shark (Rhincodon typus) and their role in visual foraging ecology
- Jeffry I. Fasick, Haya Algrain, Katherine M. Serba, Phyllis R. Robinson
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- Journal:
- Visual Neuroscience / Volume 36 / 2019
- Published online by Cambridge University Press:
- 13 November 2019, E011
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The spectral tuning properties of the whale shark (Rhincodon typus) rod (rhodopsin or Rh1) and long-wavelength-sensitive (LWS) cone visual pigments were examined to determine whether these retinal pigments have adapted to the broadband light spectrum available for surface foraging or to the narrowband blue-shifted light spectrum available at depth. Recently published whale shark genomes have identified orthologous genes for both the whale shark Rh1 and LWS cone opsins suggesting a duplex retina. Here, the whale shark Rh1 and LWS cone opsin sequences were examined to identify amino acid residues critical for spectral tuning. Surprisingly, the predicted absorbance maximum (λmax) for both the whale shark Rh1 and LWS visual pigments is near 500 nm. Although Rh1 λmax values near 500 nm are typical of terrestrial vertebrates, as well as surface foraging fish, it is uncommon for a vertebrate LWS cone pigment to be so greatly blue-shifted. We propose that the spectral tuning properties of both the whale shark Rh1 and LWS cone pigments are most likely adaptations to the broadband light spectrum available at the surface. Whale shark melanopsin (Opn4) deactivation kinetics was examined to better understand the underlying molecular mechanisms of the pupillary light reflex. Results show that the deactivation rate of whale shark Opn4 is similar to the Opn4 deactivation rate from vertebrates possessing duplex retinae and is significantly faster than the Opn4 deactivation rate from an aquatic rod monochromat lacking functional cone photoreceptors. The rapid deactivation rate of whale shark Opn4 is consistent with a functional cone class and would provide the animal with an exponential increase in the number of photons required for photoreceptor signaling when transitioning from photopic to scotopic light conditions, as is the case when diving.
Melanopsin expression in the cornea
- ANTON DELWIG, SHAWNTA Y. CHANEY, ANDREA S. BERTKE, JAN VERWEIJ, SUSANA QUIRCE, DELAINE D. LARSEN, CINDY YANG, ETHAN BUHR, RUSSELL VAN GELDER, JUANA GALLAR, TODD MARGOLIS, DAVID R. COPENHAGEN
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- Journal:
- Visual Neuroscience / Volume 35 / 2018
- Published online by Cambridge University Press:
- 31 January 2018, E004
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A unique class of intrinsically photosensitive retinal ganglion cells in mammalian retinae has been recently discovered and characterized. These neurons can generate visual signals in the absence of inputs from rods and cones, the conventional photoreceptors in the visual system. These light sensitive ganglion cells (mRGCs) express the non-rod, non-cone photopigment melanopsin and play well documented roles in modulating pupil responses to light, photoentrainment of circadian rhythms, mood, sleep and other adaptive light functions. While most research efforts in mammals have focused on mRGCs in retina, recent studies reveal that melanopsin is expressed in non-retinal tissues. For example, light-evoked melanopsin activation in extra retinal tissue regulates pupil constriction in the iris and vasodilation in the vasculature of the heart and tail. As another example of nonretinal melanopsin expression we report here the previously unrecognized localization of this photopigment in nerve fibers within the cornea. Surprisingly, we were unable to detect light responses in the melanopsin-expressing corneal fibers in spite of our histological evidence based on genetically driven markers and antibody staining. We tested further for melanopsin localization in cell bodies of the trigeminal ganglia (TG), the principal nuclei of the peripheral nervous system that project sensory fibers to the cornea, and found expression of melanopsin mRNA in a subset of TG neurons. However, neither electrophysiological recordings nor calcium imaging revealed any light responsiveness in the melanopsin positive TG neurons. Given that we found no light-evoked activation of melanopsin-expressing fibers in cornea or in cell bodies in the TG, we propose that melanopsin protein might serve other sensory functions in the cornea. One justification for this idea is that melanopsin expressed in Drosophila photoreceptors can serve as a temperature sensor.
Recurrent axon collaterals of intrinsically photosensitive retinal ganglion cells
- HANNAH R. JOO, BETH B. PETERSON, DENNIS M. DACEY, SAMER HATTAR, SHIH-KUO CHEN
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- Journal:
- Visual Neuroscience / Volume 30 / Issue 4 / July 2013
- Published online by Cambridge University Press:
- 09 July 2013, pp. 175-182
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Retinal ganglion cells (RGCs), the output neurons of the retina, have axons that project via the optic nerve to diverse targets in the brain. Typically, RGC axons do not branch before exiting the retina and thus do not provide it with synaptic feedback. Although a small subset of RGCs with intraretinal axon collaterals has been previously observed in human, monkey, cat, and turtle, their function remains unknown. A small, more recently identified population of RGCs expresses the photopigment melanopsin. These intrinsically photosensitive retinal ganglion cells (ipRGCs) transmit an irradiance-coding signal to visual nuclei in the brain, contributing both to image-forming vision and to several nonimage-forming functions, including circadian photoentrainment and the pupillary light reflex. In this study, using melanopsin immunolabeling in monkey and a genetic method to sparsely label the melanopsin cells in mouse, we show that a subgroup of ipRGCs have axons that branch en route to the optic disc, forming intraretinal axon collaterals that terminate in the inner plexiform layer of the retina. The previously described collateral-bearing population identified by intracellular dye injection is anatomically indistinguishable from the collateral-bearing melanopsin cells identified here, suggesting they are a subset of the melanopsin-expressing RGC type and may therefore share its functional properties. Identification of an anatomically distinct subpopulation in mouse, monkey, and human suggests this pathway may be conserved in these and other species (turtle and cat) with intraretinal axon collaterals. We speculate that ipRGC axon collaterals constitute a likely synaptic pathway for feedback of an irradiance signal to modulate retinal light responses.
Survival and remodeling of melanopsin cells during retinal dystrophy
- ANTHONY A. VUGLER, MA'AYAN SEMO, ANNA JOSEPH, GLEN JEFFERY
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- Journal:
- Visual Neuroscience / Volume 25 / Issue 2 / March 2008
- Published online by Cambridge University Press:
- 28 April 2008, pp. 125-138
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The melanopsin positive, intrinsically photosensitive retinal ganglion cells (ipRGCs) of the inner retina have been shown to send wide-ranging projections throughout the brain. To investigate the response of this important cell type during retinal dystrophy, we use the Royal College of Surgeons (RCS) dystrophic rat, a major model of retinal degeneration. We find that ipRGCs exhibit a distinctive molecular profile that remains unaltered during early stages of outer retinal pathology (15 weeks of age). In particular, these cells express βIII tubulin, α-acetylated tubulin, and microtubule-associated proteins (MAPs), while remaining negative for other RGC markers such as neurofilaments, calretinin, and parvalbumin. By 14 months of age, melanopsin positive fibers invade ectopic locations in the dystrophic retina and ipRGC axons/dendrites become distorted (a process that may involve vascular remodeling). The morphological abnormalities in melanopsin processes are associated with elevated immunoreactivity for MAP1b and a reduction in α-acetylated tubulin. Quantification of ipRGCs in whole mounts reveals reduced melanopsin cell number with increasing age. Focusing on the retinal periphery, we find a significant decline in melanopsin cell density contrasted by a stability of melanopsin positive processes. In addition to these findings, we describe for the first time, a distinct plexus of melanopsin processes in the far peripheral retina, a structure that is coincident with a short wavelength opsin cone-enriched rim. We conclude that some ipRGCs are lost in RCS dystrophic rats as the disease progresses and that this loss may involve vascular remodeling. However, a significant number of melanopsin positive cells survive into advanced stages of retinal degeneration and show indications of remodeling in response to pathology. Our findings underline the importance of early intervention in human retinal disease in order to preserve integrity of the inner retinal photoreceptive network.
Residual photosensitivity in mice lacking both rod opsin and cone photoreceptor cyclic nucleotide gated channel 3 α subunit
- ALUN R. BARNARD, JOANNE M. APPLEFORD, SUMATHI SEKARAN, KRISHNA CHINTHAPALLI, AARON JENKINS, MATHEAS SEELIGER, MARTIN BIEL, PETER HUMPHRIES, RON H. DOUGLAS, ANDREAS WENZEL, RUSSELL G. FOSTER, MARK W. HANKINS, ROBERT J. LUCAS
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- Journal:
- Visual Neuroscience / Volume 21 / Issue 5 / September 2004
- Published online by Cambridge University Press:
- 01 September 2004, pp. 675-683
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The mammalian retina contains three classes of photoreceptor. In addition to the rods and cones, a subset of retinal ganglion cells that express the putative sensory photopigment melanopsin are intrinsically photosensitive. Functional and anatomical studies suggest that these inner retinal photoreceptors provide light information for a number of non-image-forming light responses including photoentrainment of the circadian clock and the pupil light reflex. Here, we employ a newly developed mouse model bearing lesions of both rod and cone phototransduction cascades (Rho−/−Cnga3−/−) to further examine the function of these non-rod non-cone photoreceptors. Calcium imaging confirms the presence of inner retinal photoreceptors in Rho−/−Cnga3−/− mice. Moreover, these animals retain a pupil light reflex, photoentrainment, and light induction of the immediate early gene c-fos in the suprachiasmatic nuclei, consistent with previous findings that pupillary and circadian responses can employ inner retinal photoreceptors. Rho−/−Cnga3−/− mice also show a light-dependent increase in the number of FOS-positive cells in both the ganglion cell and (particularly) inner nuclear layers of the retina. The average number of cells affected is several times greater than the number of melanopsin-positive cells in the mouse retina, suggesting functional intercellular connections from these inner retinal photoreceptors within the retina. Finally, however, while we show that wild types exhibit an increase in heart rate upon light exposure, this response is absent in Rho−/−Cnga3−/− mice. Thus, it seems that non-rod non-cone photoreceptors can drive many, but not all, non-image-forming light responses.
Melanopsin and non-melanopsin expressing retinal ganglion cells innervate the hypothalamic suprachiasmatic nucleus
- PATRICIA J. SOLLARS, CYNTHIA A. SMERASKI, JESSICA D. KAUFMAN, MALCOLM D. OGILVIE, IGNACIO PROVENCIO, GARY E. PICKARD
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- Journal:
- Visual Neuroscience / Volume 20 / Issue 6 / November 2003
- Published online by Cambridge University Press:
- 30 March 2004, pp. 601-610
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Retinal input to the hypothalamic suprachiasmatic nucleus (SCN) synchronizes the SCN circadian oscillator to the external day/night cycle. Retinal ganglion cells that innervate the SCN via the retinohypothalamic tract are intrinsically light sensitive and express melanopsin. In this study, we provide data indicating that not all SCN-projecting retinal ganglion cells express melanopsin. To determine the proportion of ganglion cells afferent to the SCN that express melanopsin, ganglion cells were labeled following transsynaptic retrograde transport of a recombinant of the Bartha strain of pseudorabies virus (PRV152) constructed to express the enhanced green fluorescent protein (EGFP). PRV152 injected into the anterior chamber of the eye retrogradely infects four retinorecipient nuclei in the brain via autonomic circuits to the eye, resulting in transneuronally labeled ganglion cells in the contralateral retina 96 h after intraocular infection. In animals with large bilateral lesions of the lateral geniculate body/optic tract, ganglion cells labeled with PRV152 are retrogradely infected from only the SCN. In these animals, most PRV152-infected ganglion cells were immunoreactive for melanopsin. However, a significant percentage (10–20%) of EGFP-labeled ganglion cells did not express melanopsin. These data suggest that in addition to the intrinsically light-sensitive melanopsin-expressing ganglion cells, conventional ganglion cells also innervate the SCN. Thus, it appears that the rod/cone system of photoreceptors may provide signals to the SCN circadian system independent of intrinsically light-sensitive melanopsin ganglion cells.