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https://www.readbyqxmd.com/read/28103478/modulation-of-fast-narrowband-oscillations-in-the-mouse-retina-and-dlgn-according-to-background-light-intensity
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
Hanan Awad Alkozi, Xiaoyu Wang, Maria Jesus 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
https://www.readbyqxmd.com/read/27899883/commentary-melanopsin-regulates-both-sleep-promoting-and-arousal-promoting-responses-to-light
#10
COMMENT
Christian Cajochen, Sarah L Chellappa
No abstract text is available yet for this article.
2016: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/27893096/chemogenetic-activation-of-iprgcs-drives-changes-in-dark-adapted-scotopic-electroretinogram
#11
Nina Milosavljevic, Annette E Allen, Jasmina Cehajic-Kapetanovic, Robert J Lucas
Purpose: The purpose of this study was to investigate the impact of activating melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) on dark-adapted (scotopic) electroretinograms (ERG). Methods: We used mice (Opn4Cre/+) expressing cre recombinase in melanopsin-expressing cells for a targeted gene delivery of a chemogenetic Gq-coupled receptor, hM3Dq, to ipRGCs. Intraperitoneal injection of clozapine N-oxide (CNO) at 5 mg/kg was used for acute activation of hM3Dq and thus excitation of ipRGCs in darkness...
November 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27824104/degeneration-and-energy-shortage-in-the-suprachiasmatic-nucleus-underlies-the-circadian-rhythm-disturbance-in-apoe-mice-implications-for-alzheimer-s-disease
#12
Lan Zhou, Qian Gao, Meng Nie, Jing-Li Gu, Wei Hao, Lin Wang, Ji-Min Cao
Alzheimer's disease (AD) patients suffer sleep disorders and circadian rhythm disturbances (CRDs). The underlying mechanisms are incompletely understood, and treatments are lacking. In this study, we characterized the locomotor activity, clock gene expression, morphological degeneration and energy metabolism of suprachiasmatic nucleus (SCN), together with retinal light sensing, in ApoE(-/-) mice, a model for AD. Compared with the control C57BL/6J mice, ApoE(-/-) mice exhibited disordered circadian locomotor activity under dim light and constant darkness, with impaired re-entrainment to phase change schedules...
November 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27821359/pupillary-response-abnormalities-in-depressive-disorders
#13
Scott A Laurenzo, Randy Kardon, Johannes Ledolter, Pieter Poolman, Ashley M Schumacher, James B Potash, Jan M Full, Olivia Rice, Anna Ketcham, Cole Starkey, Jess G Fiedorowicz
Depressive disorders lack objective physiological measurements to characterize the affected population and facilitate study of relevant mechanisms. The melanopsin-mediated light signaling pathway may contribute to seasonal variation and can be measured non-invasively by pupillometry. We prospectively studied changes in melanopsin-mediated pupillary constriction in 19 participants with major depressive disorder (MDD) and 10 control across the summer and winter solstices. The melanopsin-mediated response, as measured by the pupil's sustained constriction six s after a high intensity blue light stimulus, was marginally attenuated in those with MDD relative to controls (p=0...
December 30, 2016: Psychiatry Research
https://www.readbyqxmd.com/read/27789727/horizontal-cells-expressing-melanopsin-x-are-novel-photoreceptors-in-the-avian-inner-retina
#14
Luis P Morera, Nicolás M Díaz, Mario E Guido
In the vertebrate retina, three types of photoreceptors-visual photoreceptor cones and rods and the intrinsically photosensitive retinal ganglion cells (ipRGCs)-converged through evolution to detect light and regulate image- and nonimage-forming activities such as photic entrainment of circadian rhythms, pupillary light reflexes, etc. ipRGCs express the nonvisual photopigment melanopsin (OPN4), encoded by two genes: the Xenopus (Opn4x) and mammalian (Opn4m) orthologs. In the chicken retina, both OPN4 proteins are found in ipRGCs, and Opn4x is also present in retinal horizontal cells (HCs), which connect with visual photoreceptors...
November 15, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27786307/coupling-optogenetic-stimulation-with-nanoluc-based-luminescence-bret-ca-sensing
#15
Jie Yang, Derrick Cumberbatch, Samuel Centanni, Shu-Qun Shi, Danny Winder, Donna Webb, Carl Hirschie Johnson
Optogenetic techniques allow intracellular manipulation of Ca(++) by illumination of light-absorbing probe molecules such as channelrhodopsins and melanopsins. The consequences of optogenetic stimulation would optimally be recorded by non-invasive optical methods. However, most current optical methods for monitoring Ca(++) levels are based on fluorescence excitation that can cause unwanted stimulation of the optogenetic probe and other undesirable effects such as tissue autofluorescence. Luminescence is an alternate optical technology that avoids the problems associated with fluorescence...
October 27, 2016: Nature Communications
https://www.readbyqxmd.com/read/27784072/the-effects-of-short-term-light-adaptation-on-the-human-post-illumination-pupil-response
#16
Daniel S Joyce, Beatrix Feigl, Andrew J Zele
Purpose: We determine the effect of short-term light adaptation on the pupil light reflex and the melanopsin mediated post-illumination pupil response (PIPR). Inner and outer retinal photoreceptor contributions to the dark-adapted pupil response were estimated. Methods: In Experiment A, light adaptation was studied using short wavelength lights ranging from subthreshold to suprathreshold irradiances for melanopsin signaling that were presented before (5-60 seconds) and after (30 seconds) a melanopsin-exciting stimulus pulse...
October 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27727394/melanopsin-phototransduction-contributes-to-light-evoked-choroidal-expansion-and-rod-l-type-calcium-channel-function-in-vivo
#17
Bruce A Berkowitz, Tiffany Schmidt, Robert H Podolsky, Robin Roberts
Purpose: In humans, rodents, and pigeons, the dark → light transition signals nonretinal brain tissue to increase choroidal thickness, a major control element of choroidal blood flow, and thus of photoreceptor and retinal pigment epithelium function. However, it is unclear which photopigments in the retina relay the light signal to the brain. Here, we test the hypothesis that melanopsin (Opn4)-regulated phototransduction modulates light-evoked choroidal thickness expansion in mice. Methods: Two-month-old C57Bl/6 wild-type (B6), 4- to 5-month-old C57Bl/6/129S6 wild-type (B6 + S6), and 2-month-old melanopsin knockout (Opn4-/-) on a B6 + S6 background were studied...
October 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27717718/ovarian-steroid-withdrawal-results-in-gabaa-receptor-upregulation-in-the-photoperiodic-neuroendocrine-pathways-of-the-turkey-hen
#18
Voravasa Chaiworakul, Sunantha Kosonsiriluk, Laura J Mauro, Mohamed E El Halawani
The mechanism(s) underlying photorefractoriness in temperate zone seasonally breeding birds remains undetermined. Our recent findings reveal a link between the upregulation of GABAA receptors (GABAARs) in the premammillary nucleus (PMM) and the state of photorefractoriness. Gonadal steroid levels fluctuate during the breeding season; increasing after gonadal recrudescence and declining sharply once gonadal regression begins. Here, we examined the effect of gonadal steroid withdrawal on the expression of GABAARs in the turkey PMM...
January 1, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/27716445/suppression-of-vagal-cardiac-modulation-by-blue-light-in-healthy-subjects
#19
Emi Yuda, Hiroki Ogasawara, Yutaka Yoshida, Junichiro Hayano
BACKGROUND: In the contemporary life environments, our body is increasingly exposed to various sources of colored light, which may affect our physiological functions as non-image-forming effects. We examined the impacts of colored lights on the autonomic functions by the analysis of heart rate variability (HRV). METHODS: A lighting device consisting of four organic light-emitting diode (OLED) modules (55 × 55 mm(2)) with adjustable red-green-blue color was secured 24 cm above the eyes of subject lying supine in a light-shielded laboratory...
October 5, 2016: Journal of Physiological Anthropology
https://www.readbyqxmd.com/read/27699209/loss-of-ikbkap-causes-slow-progressive-retinal-degeneration-in-a-mouse-model-of-familial-dysautonomia
#20
Yumi Ueki, Grisela Ramirez, Ernesto Salcedo, Maureen E Stabio, Frances Lefcort
Familial dysautonomia (FD) is an autosomal recessive congenital neuropathy that is caused by a mutation in the gene for inhibitor of kappa B kinase complex-associated protein (IKBKAP). Although FD patients suffer from multiple neuropathies, a major debilitation that affects their quality of life is progressive blindness. To determine the requirement for Ikbkap in the developing and adult retina, we generated Ikbkap conditional knockout (CKO) mice using a TUBA1a promoter-Cre (Tα1-Cre). In the retina, Tα1-Cre expression is detected predominantly in retinal ganglion cells (RGCs)...
September 2016: ENeuro
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