scholarly journals Early Appearance of Nonvisual and Circadian Markers in the Developing Inner Retinal Cells of Chicken

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Nicolás M. Díaz ◽  
Luis P. Morera ◽  
Daniela M. Verra ◽  
María A. Contin ◽  
Mario E. Guido
Keyword(s):  
Developmental Stages ◽  
Clock Genes ◽  
Ganglion Cells ◽  
Primary Cultures ◽  
Retinal Ganglion ◽  
Retinal Cells ◽  
Early Appearance ◽  
Early Developmental ◽  
The Brain ◽  
Do So

The retina is a key component of the vertebrate circadian system; it is responsible for detecting and transmitting the environmental illumination conditions (day/night cycles) to the brain that synchronize the circadian clock located in the suprachiasmatic nucleus (SCN). For this, retinal ganglion cells (RGCs) project to the SCN and other nonvisual areas. In the chicken, intrinsically photosensitive RGCs (ipRGCs) expressing the photopigment melanopsin (Opn4) transmit photic information and regulate diverse nonvisual tasks. In nonmammalian vertebrates, two genes encodeOpn4: theXenopus(Opn4x) and the mammalian (Opn4m) orthologs. RGCs express bothOpn4genes but are not the only inner retinal cells expressingOpn4x: horizontal cells (HCs) also do so. Here, we further characterize primary cultures of both populations of inner retinal cells (RGCs and HCs) expressingOpn4x. The expression of this nonvisual photopigment, as well as that for different circadian markers such as the clock genesBmal1,Clock,Per2, andCry1, and the key melatonin synthesizing enzyme, arylalkylamineN-acetyltransferase (AA-NAT), appears very early in development in both cell populations. The results clearly suggest that nonvisual Opn4 photoreceptors and endogenous clocks converge all together in these inner retinal cells at early developmental stages.

Individual-Specific Modeling of Rat Optic Nerve Head Biomechanics in Glaucoma

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Stephen A. Schwaner ◽  
Robert N. Perry ◽  
Alison M. Kight ◽  
Emily Winder ◽  
Hongli Yang ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Optic Nerve Head ◽  
Ganglion Cells ◽  
Fiber Direction ◽  
Retinal Ganglion ◽  
Main Site ◽  
Specific Geometry ◽  
Specific Modeling ◽  
The Brain ◽  
Do So

Abstract Glaucoma is the second leading cause of blindness worldwide and is characterized by the death of retinal ganglion cells (RGCs), the cells that send vision information to the brain. Their axons exit the eye at the optic nerve head (ONH), the main site of damage in glaucoma. The importance of biomechanics in glaucoma is indicated by the fact that elevated intraocular pressure (IOP) is a causative risk factor for the disease. However, exactly how biomechanical insult leads to RGC death is not understood. Although rat models are widely used to study glaucoma, their ONH biomechanics have not been characterized in depth. Therefore, we aimed to do so through finite element (FE) modeling. Utilizing our previously described method, we constructed and analyzed ONH models with individual-specific geometry in which the sclera was modeled as a matrix reinforced with collagen fibers. We developed eight sets of scleral material parameters based on results from our previous inverse FE study and used them to simulate the effects of elevated IOP in eight model variants of each of seven rat ONHs. Within the optic nerve, highest strains were seen inferiorly, a pattern that was consistent across model geometries and model variants. In addition, changing the collagen fiber direction to be circumferential within the peripapillary sclera resulted in more pronounced decreases in strain than changing scleral stiffness. The results from this study can be used to interpret data from rat glaucoma studies to learn more about how biomechanics affects RGC pathogenesis in glaucoma.

scholarly journals Cytotoxic and anti-excitotoxic effects of selected plant and algal extracts using COMET and cell viability assays

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abeer Aldbass ◽  
Musarat Amina ◽  
Nawal M. Al Musayeib ◽  
Ramesa Shafi Bhat ◽  
Sara Al-Rashed ◽  
...  
Keyword(s):  
Cell Viability ◽  
Plant Extracts ◽  
Ganglion Cells ◽  
Cell Damage ◽  
Primary Cultures ◽  
Glutamate Excitotoxicity ◽  
Retinal Ganglion ◽  
Gradual Loss ◽  
The Central Nervous System ◽  
Mtt Assays

AbstractExcess glutamate in the central nervous system may be a major cause of neurodegenerative diseases with gradual loss and dysfunction of neurons. Primary or secondary metabolites from medicinal plants and algae show potential for treatment of glutamate-induced excitotoxicity. Three plant extracts were evaluated for impact on glutamate excitotoxicity-induced in primary cultures of retinal ganglion cells (RGC). These cells were treated separately in seven groups: control; Plicosepalus. curviflorus treated; Saussurea lappa treated; Cladophora glomerate treated. Cells were treated independently with 5, 10, 50, or 100 µg/ml of extracts of plant or alga material, respectively, for 2 h. Glutamate-treated cells (48 h with 5, 10, 50, or 100 µM glutamate); and P. curviflorus/glutamate; S. lappa/glutamate; C. glomerata/glutamate [pretreatment with extract for 2 h (50 and 100 µg/ml) before glutamate treatment with 100 µM for 48 h]. Comet and MTT assays were used to assess cell damage and cell viability. The number of viable cells fell significantly after glutamate exposure. Exposure to plant extracts caused no notable effect of viability. All tested plants extracts showed a protective effect against glutamate excitotoxicity-induced RGC death. Use of these extracts for neurological conditions related to excitotoxicity and oxidative stress might prove beneficial.

scholarly journals Photoreceptive retinal ganglion cells control the information rate of the optic nerve

2018 ◽  
Vol 115 (50) ◽  
pp. E11817-E11826 ◽  
Author(s):  
Nina Milosavljevic ◽  
Riccardo Storchi ◽  
Cyril G. Eleftheriou ◽  
Andrea Colins ◽  
Rasmus S. Petersen ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Retinal Ganglion Cells ◽  
Information Flow ◽  
Information Transfer ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Ambient Light ◽  
Visual Responses ◽  
Light Irradiance ◽  
The Brain

Information transfer in the brain relies upon energetically expensive spiking activity of neurons. Rates of information flow should therefore be carefully optimized, but mechanisms to control this parameter are poorly understood. We address this deficit in the visual system, where ambient light (irradiance) is predictive of the amount of information reaching the eye and ask whether a neural measure of irradiance can therefore be used to proactively control information flow along the optic nerve. We first show that firing rates for the retina’s output neurons [retinal ganglion cells (RGCs)] scale with irradiance and are positively correlated with rates of information and the gain of visual responses. Irradiance modulates firing in the absence of any other visual signal confirming that this is a genuine response to changing ambient light. Irradiance-driven changes in firing are observed across the population of RGCs (including in both ON and OFF units) but are disrupted in mice lacking melanopsin [the photopigment of irradiance-coding intrinsically photosensitive RGCs (ipRGCs)] and can be induced under steady light exposure by chemogenetic activation of ipRGCs. Artificially elevating firing by chemogenetic excitation of ipRGCs is sufficient to increase information flow by increasing the gain of visual responses, indicating that enhanced firing is a cause of increased information transfer at higher irradiance. Our results establish a retinal circuitry driving changes in RGC firing as an active response to alterations in ambient light to adjust the amount of visual information transmitted to the brain.

Treatment In vitro of Retinal Cells with IL-4 Increases the Survival of Retinal Ganglion Cells: The Involvement of BDNF

2012 ◽  
Vol 38 (1) ◽  
pp. 162-173 ◽  
Author(s):  
Leandro de Araujo-Martins ◽  
Raphael Monteiro de Oliveira ◽  
Gabriela Velozo Gomes dos Santos ◽  
Renata Cláudia Celestino dos Santos ◽  
Aline Araujo dos Santos ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Retinal Cells

scholarly journals Blindfold learning of an accurate neural metric

2018 ◽  
Vol 115 (13) ◽  
pp. 3267-3272 ◽  
Author(s):  
Christophe Gardella ◽  
Olivier Marre ◽  
Thierry Mora
Keyword(s):  
Ganglion Cells ◽  
Direct Access ◽  
Retinal Ganglion ◽  
Boltzmann Machine ◽  
Correlated Responses ◽  
Population Activity ◽  
Spatiotemporal Structure ◽  
Distance Map ◽  
Physical Stimuli ◽  
The Brain

The brain has no direct access to physical stimuli but only to the spiking activity evoked in sensory organs. It is unclear how the brain can learn representations of the stimuli based on those noisy, correlated responses alone. Here we show how to build an accurate distance map of responses solely from the structure of the population activity of retinal ganglion cells. We introduce the Temporal Restricted Boltzmann Machine to learn the spatiotemporal structure of the population activity and use this model to define a distance between spike trains. We show that this metric outperforms existing neural distances at discriminating pairs of stimuli that are barely distinguishable. The proposed method provides a generic and biologically plausible way to learn to associate similar stimuli based on their spiking responses, without any other knowledge of these stimuli.

scholarly journals A method for single-neuron chronic recording from the retina in awake mice

Science ◽  
2018 ◽  
Vol 360 (6396) ◽  
pp. 1447-1451 ◽  
Author(s):  
Guosong Hong ◽  
Tian-Ming Fu ◽  
Mu Qiao ◽  
Robert D. Viveros ◽  
Xiao Yang ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Visual Information ◽  
Single Neuron ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Neural Circuitry ◽  
Retinal Ganglion ◽  
Chronic Recording ◽  
The Brain

The retina, which processes visual information and sends it to the brain, is an excellent model for studying neural circuitry. It has been probed extensively ex vivo but has been refractory to chronic in vivo electrophysiology. We report a nonsurgical method to achieve chronically stable in vivo recordings from single retinal ganglion cells (RGCs) in awake mice. We developed a noncoaxial intravitreal injection scheme in which injected mesh electronics unrolls inside the eye and conformally coats the highly curved retina without compromising normal eye functions. The method allows 16-channel recordings from multiple types of RGCs with stable responses to visual stimuli for at least 2 weeks, and reveals circadian rhythms in RGC responses over multiple day/night cycles.

Intrinsic physiological properties of rat retinal ganglion cells with a comparative analysis

2012 ◽  
Vol 108 (7) ◽  
pp. 2008-2023 ◽  
Author(s):  
Raymond C. S. Wong ◽  
Shaun L. Cloherty ◽  
Michael R. Ibbotson ◽  
Brendan J. O'Brien
Keyword(s):  
Ganglion Cells ◽  
Mammalian Species ◽  
Cell Types ◽  
Retinal Ganglion ◽  
Intrinsic Properties ◽  
Cat Retina ◽  
Physiological Properties ◽  
Behavioral Needs ◽  
Mammalian Retina ◽  
Do So

Mammalian retina contains 15–20 different retinal ganglion cell (RGC) types, each of which is responsible for encoding different aspects of the visual scene. The encoding is defined by a combination of RGC synaptic inputs, the neurotransmitter systems used, and their intrinsic physiological properties. Each cell's intrinsic properties are defined by its morphology and membrane characteristics, including the complement and localization of the ion channels expressed. In this study, we examined the hypothesis that the intrinsic properties of individual RGC types are conserved among mammalian species. To do so, we measured the intrinsic properties of 16 morphologically defined rat RGC types and compared these data with cat RGC types. Our data demonstrate that in the rat different morphologically defined RGC types have distinct patterns of intrinsic properties. Variation in these properties across cell types was comparable to that found for cat RGC types. When presumed morphological homologs in rat and cat retina were compared directly, some RGC types had very similar properties. The rat A2 cell exhibited patterns of intrinsic properties nearly identical to the cat alpha cell. In contrast, rat D2 cells (ON-OFF directionally selective) had a very different pattern of intrinsic properties than the cat iota cell. Our data suggest that the intrinsic properties of RGCs with similar morphology and suspected visual function may be subject to variation due to the behavioral needs of the species.

The Biomechanical Response of Normal and Glaucoma Human Sclera

2010 ◽  
Author(s):  
Baptiste Coudrillier ◽  
Kristin M. Myers ◽  
Thao D. Nguyen
Keyword(s):  
Retinal Ganglion Cells ◽  
Material Properties ◽  
Visual Information ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Progressive Degeneration ◽  
Biomechanical Response ◽  
Elevated Intraocular Pressure ◽  
The Relationship ◽  
The Brain

By 2010, 60 million people will have glaucoma, the second leading cause of blindness worldwide [1]. The disease is characterized by a progressive degeneration of the retinal ganglion cells (RGC), a type of neuron that transmits visual information to the brain. It is well know that elevated intraocular pressure (IOP) is a risk factor in the damage to the RGCs [3–5], but the relationship between the mechanical properties of the ocular connective tissue and how it affects cellular function is not well characterized. The cornea and the sclera are collage-rich structures that comprise the outer load-bearing shell of the eye. Their preferentially aligned collagen lamellae provide mechanical strength to resist ocular expansion. Previous uniaxial tension studies suggest that altered viscoelastic material properties of the eye wall play a role in glaucomatous damage [6].

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