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https://www.readbyqxmd.com/read/28271634/choroideremia-melanopsin-mediated-postillumination-pupil-relaxation-is-abnormally-slow
#1
Shakoor Ba-Ali, Søren Kirchhoff Christensen, Birgit Sander, Thomas Rosenberg, Michael Larsen, Henrik Lund-Andersen
PURPOSE: To investigate the rod-cone and melanopsin pupillary light response (PLR) pathways in choroideremia. METHODS: Eight patients with choroideremia and 18 healthy age-matched controls underwent chromatic pupillometry by applying blue (463 nm) and red light (643 nm) at 100 lux intensity to the right eye while recording pupil diameters. Absolute baseline pupil size (mm), normalized maximal pupil constriction and the early and late postillumination pupillary dilation, from 0 to 10 seconds and 10 to 30 seconds after the end of illumination, respectively, were determined...
March 8, 2017: Acta Ophthalmologica
https://www.readbyqxmd.com/read/28266650/pupillary-responses-to-short-wavelength-light-are-preserved-in-aging
#2
A V Rukmini, Dan Milea, Tin Aung, Joshua J Gooley
With aging, less blue light reaches the retina due to gradual yellowing of the lens. This could result in reduced activation of blue light-sensitive melanopsin-containing retinal ganglion cells, which mediate non-visual light responses (e.g., the pupillary light reflex, melatonin suppression, and circadian resetting). Herein, we tested the hypothesis that older individuals show greater impairment of pupillary responses to blue light relative to red light. Dose-response curves for pupillary constriction to 469-nm blue light and 631-nm red light were compared between young normal adults aged 21-30 years (n = 60) and older adults aged ≥50 years (normal, n = 54; mild cataract, n = 107; severe cataract, n = 18)...
March 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28264100/the-relation-between-light-induced-lacrimation-and-the-melanopsin-driven-postillumination-pupil-response
#3
Shaobo Lei, Herbert C Goltz, Xingqiao Chen, Marija Zivcevska, Agnes M F Wong
Purpose: To investigate the chromatic characteristics and intensity-response function of light-induced reflex lacrimation and its correlation with the melanopsin-driven postillumination pupil response (PIPR). Methods: Eleven visually normal participants completed the experiment. Lacrimation was measured in one eye by placing a calibrated filter paper strip in the conjunctival sac over a 1 minute-interval (Schirmer's test) during which participants received either no light stimulation (baseline trial) or one flash of blue or red light stimuli presented binocularly with a Ganzfeld stimulator, while the pupil response was recorded simultaneously from the fellow eye by using an eye tracker...
March 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28251921/clinical-implications-of-the-melanopsin-based-non-image-forming-visual-system
#4
Alexander Ksendzovsky, I Jonathan Pomeraniec, Kareem A Zaghloul, J Javier Provencio, Ignacio Provencio
Since the discovery of the non-image-forming visual system, tremendous research efforts have been dedicated to understanding its mechanisms and functional roles. Original functions associated with the melanopsin system include the photoentrainment of circadian sleep-wake cycles and the pupillary light reflex. Recent findings, however, suggest a much broader involvement of this system in an array of physiologic responses to light. This newfound insight into the underlying function of the non-image-forming system has revealed the many connections to human pathology and attendant disease states, including seasonal affective disorder, migraine, glaucoma, inherited mitochondrial optic neuropathy, and sleep dysregulation of aging...
March 1, 2017: Neurology
https://www.readbyqxmd.com/read/28223508/c-terminal-phosphorylation-regulates-the-kinetics-of-a-subset-of-melanopsin-mediated-behaviors-in-mice
#5
Preethi Somasundaram, Glenn R Wyrick, Diego Carlos Fernandez, Alireza Ghahari, Cindy M Pinhal, Melissa Simmonds Richardson, Alan C Rupp, Lihong Cui, Zhijian Wu, R Lane Brown, Tudor Constantin Badea, Samer Hattar, Phyllis R Robinson
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin and mediate several non-image-forming visual functions, including circadian photoentrainment and the pupillary light reflex (PLR). ipRGCs act as autonomous photoreceptors via the intrinsic melanopsin-based phototransduction pathway and as a relay for rod/cone input via synaptically driven responses. Under low light intensities, where only synaptically driven rod/cone input activates ipRGCs, the duration of the ipRGC response will be determined by the termination kinetics of the rod/cone circuits...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28160289/melanopsin-expressing-human-retinal-ganglion-cells-subtypes-distribution-and-intraretinal-connectivity
#6
Jens Hannibal, Anders Tolstrup Christiansen, Steffen Heegaard, Jan Fahrenkrug, Jens Folke Kiilgaard
Intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin belong to a heterogenic population of RGCs which regulate the circadian clock, masking behavior, melatonin suppression, the pupillary light reflex and sleep/wake cycles. The different functions seem to be associated to different subtypes of melanopsin cells. In rodents, subtype classification has associated subtypes to function. In primate and human retina such classification has so far, not been applied. In the present study using antibodies against N- and C-terminal parts of human melanopsin, confocal microscopy and 3D reconstruction of melanopsin immunoreactive (-ir) RGCs, we applied the criteria used in mouse on human melanopsin-ir RGCs...
February 3, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28153865/mechanisms-creating-transient-and-sustained-photoresponses-in-mammalian-retinal-ganglion-cells
#7
Xiwu Zhao, Aaron N Reifler, Melanie M Schroeder, Elizabeth R Jaeckel, Andrew P Chervenak, Kwoon Y Wong
Retinal neurons use sustained and transient light responses to encode visual stimuli of different frequency ranges, but the underlying mechanisms remain poorly understood. In particular, although earlier studies in retinal ganglion cells (RGCs) proposed seven potential mechanisms, all seven have since been disputed, and it remains unknown whether different RGC types use different mechanisms or how many mechanisms are used by each type. Here, we conduct a comprehensive survey in mice and rats of 12 candidate mechanisms that could conceivably produce tonic rod/cone-driven ON responses in intrinsically photosensitive RGCs (ipRGCs) and transient ON responses in three types of direction-selective RGCs (TRHR+, Hoxd10+ ON, and Hoxd10+ ON-OFF cells)...
March 6, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28143576/enhancement-of-autonomic-and-psychomotor-arousal-by-exposures-to-blue-wavelength-light-importance-of-both-absolute-and-relative-contents-of-melanopic-component
#8
Emi Yuda, Hiroki Ogasawara, Yutaka Yoshida, Junichiro Hayano
BACKGROUND: Blue light containing rich melanopsin-stimulating (melanopic) component has been reported to enhance arousal level, but it is unclear whether the determinant of the effects is the absolute or relative content of melanopic component. We compared the autonomic and psychomotor arousal effects of melanopic-enriched blue light of organic light-emitting diode (OLED) with those of OLED lights with lesser absolute amount of melanopic component (green light) and with greater absolute but lesser relative content (white light)...
January 31, 2017: Journal of Physiological Anthropology
https://www.readbyqxmd.com/read/28135360/retinal-architecture-and-melanopsin-mediated-pupillary-response-characteristics-a-putative-pathophysiologic-signature-for-the-retino-hypothalamic-tract-in-multiple-sclerosis
#9
Ethan Meltzer, Peter V Sguigna, Adnan Subei, Shin Beh, Eric Kildebeck, Darrel Conger, Amy Conger, Marlen Lucero, Benjamin S Frohman, Ashley N Frohman, Shiv Saidha, Steven Galetta, Peter A Calabresi, Robert Rennaker, Teresa C Frohman, Randy H Kardon, Laura J Balcer, Elliot M Frohman
Importance: A neurophysiologic signature of the melanopsin-mediated persistent constriction phase of the pupillary light reflex may represent a surrogate biomarker for the integrity of the retinohypothalamic tract, with potential utility for investigating alterations in homeostatic mechanisms associated with brain disorders and implications for identifying new treatments. Objective: To characterize abnormalities of retinal architecture in patients with multiple sclerosis (MS) and corresponding alterations in the melanopsin-mediated sustained pupillary constriction response...
January 30, 2017: JAMA Neurology
https://www.readbyqxmd.com/read/28135345/melanopsin-effects-on-pupil-responses-is-the-eye-the-window-to-the-weary-soul
#10
Owen B White, Fiona Costello
No abstract text is available yet for this article.
January 30, 2017: JAMA Neurology
https://www.readbyqxmd.com/read/28119450/ectopic-expression-of-mouse-melanopsin-in-drosophila-photoreceptors-reveals-fast-response-kinetics-and-persistent-dark-excitation
#11
Bushra Yasin, Elkana Kohn, Maximilian Peters, Rachel Zaguri, Shirley Weiss, Krystina Schopf, Ben Katz, Armin Huber, Baruch Minke
The intrinsically photosensitive retinal ganglion cells (ipRGC) initiate non-image forming light-dependent activities and express the melanopsin (OPN4) photopigment. Several features of ipRGC photosensitivity are characteristic of fly photoreceptors. However, the light-response kinetics of ipRGC is much slower due to unknown reasons. Here we used transgenic Drosophila, in which the mouse OPN4 replaced the native Rh1 photopigment of Drosophila R1-6 photoreceptors, resulting in deformed rhabdomeric structure...
January 24, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28103478/modulation-of-fast-narrowband-oscillations-in-the-mouse-retina-and-dlgn-according-to-background-light-intensity
#12
Riccardo Storchi, Robert A Bedford, Franck P Martial, Annette E Allen, Jonathan Wynne, Marcelo A Montemurro, Rasmus S Petersen, Robert J Lucas
Background light intensity (irradiance) substantially impacts the visual code in the early visual system at synaptic and single-neuron levels, but its influence on population activity is largely unexplored. We show that fast narrowband oscillations, an important feature of population activity, systematically increase in amplitude as a function of irradiance in both anesthetized and awake, freely moving mice and at the level of the retina and dorsal lateral geniculate nucleus (dLGN). Narrowband coherence increases with irradiance across large areas of the dLGN, but especially for neighboring units...
January 18, 2017: Neuron
https://www.readbyqxmd.com/read/28097654/melanopsin-expressing-ganglion-cells-in-human-retina-morphology-distribution-and-synaptic-connections
#13
Subha Nasir-Ahmad, Sammy C S Lee, Paul R Martin, Ulrike Grünert
Melanopsin-expressing retinal ganglion cells are intrinsically photosensitive cells that are involved in non-image forming visual processes such as the pupillary light reflex and circadian entrainment but also contribute to visual perception. Here we used immunohistochemistry to study the morphology, density, distribution and synaptic connectivity of melanopsin-expressing ganglion cells in four post mortem human donor retinas. Two types of melanopsin-expressing ganglion cells were distinguished based on their dendritic stratification near either the outer or the inner border of the inner plexiform layer...
January 18, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28061512/assessment-of-rod-cone-and-intrinsically-photosensitive-retinal-ganglion-cell-contributions-to-the-canine-chromatic-pupillary-response
#14
Connie Y Yeh, Kristin L Koehl, Christine D Harman, Simone Iwabe, José M Guzman, Simon M Petersen-Jones, Randy H Kardon, András M Komáromy
Purpose: The purpose of this study was to evaluate a chromatic pupillometry protocol for specific functional assessment of rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) in dogs. Methods: Chromatic pupillometry was tested and compared in 37 dogs in different stages of primary loss of rod, cone, and combined rod/cone and optic nerve function, and in 5 wild-type (WT) dogs. Eyes were stimulated with 1-s flashes of dim (1 cd/m2) and bright (400 cd/m2) blue light (for scotopic conditions) or bright red (400 cd/m2) light with 25-cd/m2 blue background (for photopic conditions)...
January 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28031289/attenuated-pupillary-light-responses-and-downregulation-of-opsin-expression-parallel-decline-in-circadian-disruption-in-two-different-mouse-models-of-huntington-s-disease
#15
Koliane Ouk, Steven Hughes, Carina A Pothecary, Stuart N Peirson, A Jennifer Morton
Circadian deficits in Huntington's disease (HD) are recapitulated in both fragment (R6/2) and full-length (Q175) mouse models of HD. Circadian rhythms are regulated by the suprachiasmatic nuclei (SCN) in the hypothalamus, which are primarily entrained by light detected by the retina. The SCN receives input from intrinsically photosensitive retinal ganglion cells (ipRGCs) that express the photopigment melanopsin, but also receive input from rods and cones. In turn, ipRGCs mediate a range of non-image forming responses to light including circadian entrainment and the pupillary light response (PLR)...
December 27, 2016: Human Molecular Genetics
https://www.readbyqxmd.com/read/28003454/modulation-of-recognition-memory-performance-by-light-requires-both-melanopsin-and-classical-photoreceptors
#16
Shu K E Tam, Sibah Hasan, Steven Hughes, Mark W Hankins, Russell G Foster, David M Bannerman, Stuart N Peirson
Acute light exposure exerts various effects on physiology and behaviour. Although the effects of light on brain network activity in humans are well demonstrated, the effects of light on cognitive performance are inconclusive, with the size, as well as direction, of the effect depending on the nature of the task. Similarly, in nocturnal rodents, bright light can either facilitate or disrupt performance depending on the type of task employed. Crucially, it is unclear whether the effects of light on behavioural performance are mediated via the classical image-forming rods and cones or the melanopsin-expressing photosensitive retinal ganglion cells...
December 28, 2016: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/27997691/survey-of-retinal-ganglion-cell-morphology-in-marmoset
#17
Rania A Masri, Kumiko A Percival, Amane Koizumi, Paul R Martin, Ulrike Grünert
In primate retina, the midget, parasol, and small bistratified cell populations form the large majority of ganglion cells. In addition, there is a variety of low-density wide-field ganglion cell types, which are less well characterized. Here we studied retinal ganglion cells in the common marmoset, Callithrix jacchus, using particle-mediated gene-transfer. Ganglion cells were transfected with an expression plasmid for the postsynaptic density 95-green fluorescent protein. The retinas were processed with established immunohistochemical markers for bipolar and/or amacrine cells in order to determine ganglion cell dendritic stratification...
December 20, 2016: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/27992553/intrinsically-photosensitive-retinal-ganglion-cells-iprgcs-are-necessary-for-light-entrainment-of-peripheral-clocks
#18
Paulo Kofuji, Ludovic S Mure, Logan J Massman, Nicole Purrier, Satchidananda Panda, William C Engeland
Light is a powerful entrainer of circadian clocks in almost all eukaryotic organisms promoting synchronization of internal circadian rhythms with external environmental light-dark (LD) cycles. In mammals, the circadian system is organized in a hierarchical manner, in which a central pacemaker in the suprachiasmatic nucleus (SCN) synchronizes oscillators in peripheral tissues. Recent evidence demonstrates that photoentrainment of the SCN proceeds via signaling from a subpopulation of retinal ganglion cells (RGCs) which are melanopsin-expressing and intrinsically photosensitive (ipRGCs)...
2016: PloS One
https://www.readbyqxmd.com/read/27930778/melanopsin-containing-or-non-melanopsin-containing-retinal-ganglion-cells-response-to-acute-ocular-hypertension-with-or-without-brain-derived-neurotrophic-factor-neuroprotection
#19
Giuseppe Rovere, Francisco M Nadal-Nicolás, Jiawei Wang, Jose M Bernal-Garro, Nuria García-Carrillo, Maria Paz Villegas-Pérez, Marta Agudo-Barriuso, Manuel Vidal-Sanz
Purpose: To analyze the responses of different retinal ganglion cell (RGC) types to acute ocular hypertension (AOH) and intravitreal administration of brain-derived neurotrophic factor (BDNF). Methods: In adult albino rats, the anterior chamber of the left eye was cannulated with a needle connected to a saline container elevated 1½ meters above the eye for 75 minutes. Rats received 12 hours before a 5 μl intravitreal injection containing 5 μg BDNF in 1% albumin PBS or vehicle and were analyzed 3, 7, 14, or 45 days later...
December 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27914990/presence-of-melanopsin-in-human-crystalline-lens-epithelial-cells-and-its-role-in-melatonin-synthesis
#20
Hanan Awad Alkozi, Xiaoyu Wang, Maria J Perez de Lara, Jesus Pintor
Melanopsin is a non-image forming photoreceptor known to be present in the retina and it is considered to have light regulated tasks among other functions. In the present work, melanopsin presence in human lens epithelial cells as well as in human lens tissue is described for the first time. Moreover, studying the concentration of melatonin and its synthesising enzyme AANAT proved a clear link between melanopsin activation and the suppression of melatonin synthesis. Melanopsin sensitivity to specific wavelength (465-480 nm, blue) was confirmed after making temporal studies incubating lens epithelial cells under light, red, green, blue and total darkness for 2, 4, 8, 12 h and analysing the concentration of both melatonin and its synthesising enzyme AANAT, discovering that melatonin levels after submitting cells to total darkness are significantly higher to ones submitted to white or specifically blue light (***p < 0...
November 30, 2016: Experimental Eye Research
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