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Retinal signal processing

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https://www.readbyqxmd.com/read/30310139/gravity-dependent-change-in-the-light-from-above-prior
#1
Michael Barnett-Cowan, Marc O Ernst, Heinrich H Bülthoff
In environments where orientation is ambiguous, the visual system uses prior knowledge about lighting coming from above to recognize objects, determine which way is up, and reorient the body. Here we investigated the extent with which assumed light from above preferences are affected by body orientation and the orientation of the retina relative to gravity. We tested the ability to extract shape-from-shading with seven human male observers positioned in multiple orientations relative to gravity using a modified KUKA anthropomorphic robot arm...
October 11, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30299254/range-routing-and-kinetics-of-rod-signaling-in-primate-retina
#2
William N Grimes, Jacob Baudin, Anthony W Azevedo, Fred Rieke
Stimulus- or context-dependent routing of neural signals through parallel pathways can permit flexible processing of diverse inputs. For example, work in mouse shows that rod photoreceptor signals are routed through several retinal pathways, each specialized for different light levels. This light-level-dependent routing of rod signals has been invoked to explain several human perceptual results, but it has not been tested in primate retina. Here we show, surprisingly, that rod signals traverse the primate retina almost exclusively through a single pathway - the dedicated rod bipolar pathway...
October 9, 2018: ELife
https://www.readbyqxmd.com/read/30289073/vegfr2-and-vegf-c-suppresses-the-epithelial-mesenchymal-transition-via-yap-in-retinal-pigment-epi%C3%A2-thelial-cells
#3
Y Du, Q Chen, L Huang, S Wang, X Yin, L Zhou, Z Ye, X Ren, Y Cai, X Ding, H Ouyang, X Li, R Ju
BACKGROUND: Whereas retinal pigment epithelial (RPE) cells are known to secrete VEGF-A and VEGFR2, the functions of the autocrine VEGF signaling remain unclear. Meanwhile, anti-VEGF therapies have been applied routinely to treat ocular vascular diseases. OBJECTIVE: The aim of this study was to determine the functions of the VEGF signaling in RPE cells and evaluate the consequences of its interruption. METHODS: The genes involved in the VEGF and Hippo signal pathways were knocked down with siRNAs in both ARPE-19 cell line and human primary RPE cells via transient transfection whereas overexpression of VEGFR2 was mediated via adenovirus transduction...
October 4, 2018: Current Molecular Medicine
https://www.readbyqxmd.com/read/30286168/fractional-integral-like-processing-in-retinal-cones-reduces-noise-and-improves-adaptation
#4
Antal Martinecz, Mihoko Niitsuma
In the human retina, rod and cone cells detect incoming light with a molecule called rhodopsin. After rhodopsin molecules are activated (by photon impact), these molecules activate the rest of the signalling process for a brief period of time until they are deactivated by a multistage process. First, active rhodopsin is phosphorylated multiple times. Following this, they are further inhibited by the binding of molecules called arrestins. Finally, they decay into opsins. The time required for each of these stages becomes progressively longer, and each stage further reduces the activity of rhodopsin...
2018: PloS One
https://www.readbyqxmd.com/read/30283778/validating-the-redmit-gfp-lc3-mouse-model-by-studying-mitophagy-in-autosomal-dominant-optic-atrophy-due-to-the-opa1q285stop-mutation
#5
Alan Diot, Thomas Agnew, Jeremy Sanderson, Chunyan Liao, Janet Carver, Ricardo Pires das Neves, Rajeev Gupta, Yanping Guo, Caroline Waters, Sharon Seto, Matthew J Daniels, Eszter Dombi, Tiffany Lodge, Karl Morten, Suzannah A Williams, Tariq Enver, Francisco J Iborra, Marcela Votruba, Joanna Poulton
Background: Autosomal dominant optic atrophy (ADOA) is usually caused by mutations in the essential gene, OPA1. This encodes a ubiquitous protein involved in mitochondrial dynamics, hence tissue specificity is not understood. Dysregulated mitophagy (mitochondria recycling) is implicated in ADOA, being increased in OPA1 patient fibroblasts. Furthermore, autophagy may be increased in retinal ganglion cells (RGCs) of the OPA1Q285STOP mouse model. Aims: We developed a mouse model for studying mitochondrial dynamics in order to investigate mitophagy in ADOA...
2018: Frontiers in Cell and Developmental Biology
https://www.readbyqxmd.com/read/30279732/g%C3%AE-i1-and-g%C3%AE-i3mediate-vegf-induced-vegfr2-endocytosis-signaling-and-angiogenesis
#6
Jian Sun, Wei Huang, Shuo-Fei Yang, Xiao-Pei Zhang, Qing Yu, Zhi-Qing Zhang, Jin Yao, Ke-Ran Li, Qin Jiang, Cong Cao
VEGF binding to VEGFR2 leads to VEGFR2 endocytosis and downstream signaling activation to promote angiogenesis. Methods: Using genetic strategies, we tested the requirement of α subunits of heterotrimeric G proteins (Gαi1/3) in the process. Results: Gαi1/3 are located in the VEGFR2 endocytosis complex (VEGFR2-Ephrin-B2-Dab2-PAR-3), where they are required for VEGFR2 endocytosis and downstream signaling transduction. Gαi1/3 knockdown, knockout or dominant negative mutation inhibited VEGF-induced VEGFR2 endocytosis, and downstream Akt-mTOR and Erk-MAPK activation...
2018: Theranostics
https://www.readbyqxmd.com/read/30266148/temporal-coding-of-visual-space
#7
REVIEW
Michele Rucci, Ehud Ahissar, David Burr
Establishing a representation of space is a major goal of sensory systems. Spatial information, however, is not always explicit in the incoming sensory signals. In most modalities it needs to be actively extracted from cues embedded in the temporal flow of receptor activation. Vision, on the other hand, starts with a sophisticated optical imaging system that explicitly preserves spatial information on the retina. This may lead to the assumption that vision is predominantly a spatial process: all that is needed is to transmit the retinal image to the cortex, like uploading a digital photograph, to establish a spatial map of the world...
October 2018: Trends in Cognitive Sciences
https://www.readbyqxmd.com/read/30258702/baseline-detrending-for-the-photopic-negative-response
#8
Jessica Tang, Flora Hui, Michael Coote, Jonathan G Crowston, Xavier Hadoux
Purpose: The photopic negative response (PhNR) of the light-adapted electroretinogram (ERG) holds promise as an objective marker of retinal ganglion cell function. We compared baseline detrending methods to improve PhNR repeatability without compromising its diagnostic ability in glaucoma. Methods: Photopic ERGs were recorded in 20 glaucoma and 18 age-matched control participants. A total of 50 brief, red-flashes (1.6 cd.s/m2 ) on a blue background (10 photopic cd/m2 ) were delivered using the RETeval device...
September 2018: Translational Vision Science & Technology
https://www.readbyqxmd.com/read/30255622/young-bone-marrow-sca-1-cells-protect-aged-retina-from-ischaemia-reperfusion-injury-through-activation-of-fgf2
#9
Zhengbo Shao, Jie Wu, Guoqing Du, Huifang Song, Shu-Hong Li, Sheng He, Jiao Li, Jun Wu, Richard D Weisel, Huiping Yuan, Ren-Ke Li
Retinal ganglion cell apoptosis and optic nerve degeneration are prevalent in aged patients, which may be related to the decrease in bone marrow (BM) stem cell number/function because of the possible cross-talk between the two organs. This pathological process is accelerated by retinal ischaemia-reperfusion (I/R) injury. This study investigated whether young BM stem cells can regenerate and repair the aged retina after acute I/R injury. Young BM stem cell antigen 1 positive (Sca-1+ ) or Sca-1- cells were transplanted into lethally irradiated aged recipient mice to generate Sca-1+ and Sca-1- chimaeras, respectively...
September 25, 2018: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/30252955/a-ferroelectric-electrochemical-modulated-organic-synapse-for-ultraflexible-artificial-visual-perception-system
#10
Hanlin Wang, Qiang Zhao, Zhenjie Ni, Qingyuan Li, Hongtao Liu, Yunchang Yang, Lifeng Wang, Yang Ran, Yunlong Guo, Wenping Hu, Yunqi Liu
Human eyes undertake the majority of information assimilation for learning and memory. Transduction of the color and intensity of the incident light into neural signals is the main process for visual perception. Besides light-sensitive elements that function as rods and cones, artificial retinal systems require neuromorphic devices to transform light stimuli into post-synaptic signals. In terms of plasticity timescale, synapses with short-term plasticity (STP) and long-term potentiation (LTP) represent the neural foundation for experience acquisition and memory formation...
September 25, 2018: Advanced Materials
https://www.readbyqxmd.com/read/30250425/clinical-impact-of-spontaneous-hyperactivity-in-degenerating-retinas-significance-for-diagnosis-symptoms-and-treatment
#11
Steven F Stasheff
Hereditary retinal degenerations result from varied pathophysiologic mechanisms, all ultimately characterized by photoreceptor dysfunction and death. Hence, much research on these diseases has concentrated on the outer retina. Over the past decade or so increasing attention has focused on concomitant changes in complex inner retinal neural circuits that process visual signals for transmission to the brain. One striking abnormality develops before the ultimately profound anatomic disruption of the inner retina...
2018: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/30225342/visual-temporal-contrast-sensitivity-in-the-behaving-mouse-shares-fundamental-properties-with-human-psychophysics
#12
Yumiko Umino, Rose Pasquale, Eduardo Solessio
The mammalian visual system has a remarkable capacity to detect differences in contrast across time, which is known as temporal contrast sensitivity (TCS). Details of the underlying neural mechanisms are rapidly emerging as a result of a series of elegant electrophysiological studies performed largely with the mouse as an experimental model. However, rigorous psychophysical methods are necessary to pair the electrophysiology with temporal visual behavior in mouse. The optomotor response is frequently used as a proxy for retinal temporal processing in rodents...
July 2018: ENeuro
https://www.readbyqxmd.com/read/30208636/extract-of-the-blood-circulation-promoting-recipe-84-can-protect-rat-retinas-by-inhibiting-the-%C3%AE-catenin-signaling-pathway
#13
Qiu-Fang Qin, Min Liu, Gui-Hua Tian, Jian Chen, Yu-Sang Li
Extract of the Blood Circulation-Promoting Recipe (EBR-84) from the Chinese Herbal medicine "Blood Circulation Promoting Recipe" could retard retinopathy development. This study investigated whether EBR-84 protects retinas by inhibiting the β-catenin pathway using a rat model of retinopathy and a retinal ganglion cell 5 (RGC-5) cell death model. RGC death was induced by either N -methyl-d-aspartic acid (NMDA) or TWS119 (an activator of the β-catenin pathway). After the corresponding treatment with EBR-84, RGC death and the protein expression levels of β-catenin, cyclooxygenase-2 (COX-2), and vascular endothelial growth factor (VEGF) in rat retinas were examined...
September 11, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/30188320/receptive-field-center-surround-interactions-mediate-context-dependent-spatial-contrast-encoding-in-the-retina
#14
Maxwell H Turner, Gregory W Schwartz, Fred Rieke
Antagonistic receptive field surrounds are a near-universal property of early sensory processing. A key assumption in many models for retinal ganglion cell encoding is that receptive field surrounds are added only to the fully formed center signal. But anatomical and functional observations indicate that surrounds are added before the summation of signals across receptive field subunits that creates the center. Here, we show that this receptive field architecture has an important consequence for spatial contrast encoding in the macaque monkey retina: the surround can control sensitivity to fine spatial structure by changing the way the center integrates visual information over space...
September 6, 2018: ELife
https://www.readbyqxmd.com/read/30187432/a-virtual-reality-approach-identifies-flexible-inhibition-of-motion-aftereffects-induced-by-head-rotation
#15
Jianying Bai, Min Bao, Tao Zhang, Yi Jiang
As we move in space, our retinae receive motion signals from two causes: those resulting from motion in the world and those resulting from self-motion. Mounting evidence has shown that vestibular self-motion signals interact with visual motion processing profoundly. However, most contemporary methods arguably lack portability and generality and are incapable of providing measurements during locomotion. Here we developed a virtual reality approach, combining a three-space sensor with a head-mounted display, to quantitatively manipulate the causality between retinal motion and head rotations in the yaw plane...
September 5, 2018: Behavior Research Methods
https://www.readbyqxmd.com/read/30186230/succinate-as-a-regulator-of-hepatic-stellate-cells-in-liver-fibrosis
#16
REVIEW
Eun-Hee Cho
The rapid increase of obesity rates worldwide is associated with chronic liver injury due to non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. Chronic liver inflammation drives hepatic fibrosis, which is a highly conserved and coordinated protective response to tissue injury, and is a reversible process. Hepatocytes, immune cells, and hepatic stellate cells (HSCs) have been identified as key players in the mechanisms of hepatic fibrosis and inflammation. During the last decade, succinate, an intermediate of the tricarboxylic acid cycle in mitochondrial ATP production, has emerged as an important signaling molecule in various diseases...
2018: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/30174136/prpf4-is-essential-for-cell-survival-and-posterior-lateral-line-primordium-migration-in-zebrafish
#17
Yixia Wang, Yanchao Han, Pengfei Xu, Shihui Ding, Guangyuan Li, Hongbin Jin, Yaping Meng, Anming Meng, Shunji Jia
Prpf4 (pre-mRNA processing factor 4), a key component of spliceosome, plays critical roles in pre-mRNA splicing and its mutations result in retinitis pigmentosa due to photoreceptor defects. In this study, we characterized a zebrafish prpf4t243 mutant harboring a Tol2 transposon-based gene trap cassette in the third intron of the prpf4 gene. Cells in the brain and spinal cord gradually undergo p53-dependent apoptosis after 28 hpf in prpf4t243 mutants, suggesting that a widespread function of prpf4 in neural cell survival...
August 7, 2018: Journal of Genetics and Genomics, Yi Chuan Xue Bao
https://www.readbyqxmd.com/read/30171858/can-an-in-vivo-imaging-system-be-used-to-determine-localization-and-biodistribution-of-aav5-mediated-gene-expression-following-subretinal-and-intravitreal-delivery-in-mice
#18
Raaya Ezra-Elia, Alexey Obolensky, Ayala Ejzenberg, Maya Ross, Dvir Mintz, Eyal Banin, Ron Ofri
Recombinant adeno associated viruses (AAV) are the most commonly used vectors in animal model studies of gene therapy for retinal diseases. The ability of a vector to localize and remain in the target tissue, and in this manner to avoid off-target effects beyond the site of delivery, is critical to the efficacy and safety of the treatment. The in vivo imaging system (IVIS) is a non-invasive imaging tool used for detection and quantification of bioluminescence activity in rodents. Our aim was to investigate whether IVIS can detect localization and biodistribution of AAV5 vector in mice following subretinal (SR) and intravitreal (IVT) injections...
August 29, 2018: Experimental Eye Research
https://www.readbyqxmd.com/read/30161079/visualization-of-the-lamina-cribrosa-microvasculature-in-normal-and-glaucomatous-eyes-a-swept-source-optical-coherence-tomography-angiography-study
#19
Shogo Numa, Tadamichi Akagi, Akihito Uji, Kenji Suda, Hideo Nakanishi, Takanori Kameda, Hanako Ohashi Ikeda, Akitaka Tsujikawa
PURPOSE: The purpose of this study was to investigate the lamina cribrosa (LC) microvasculature using swept-source (SS) optical coherence tomography angiography (OCTA) images that have been processed using multiple image averaging and a projection-resolved algorithm. OCTA has recently gained popularity for assessing retinal and choroidal microvasculature. However, it is not known if the LC microvasculature, which likely holds important information for further understanding of glaucoma, can be visualized with OCTA...
August 29, 2018: Journal of Glaucoma
https://www.readbyqxmd.com/read/30158523/revisiting-the-functional-significance-of-binocular-cues-for-perceiving-motion-in-depth
#20
Peter J Kohler, Wesley J Meredith, Anthony M Norcia
Binocular differencing of spatial cues required for perceiving depth relationships is associated with decreased sensitivity to the corresponding retinal image displacements. However, binocular summation of contrast signals increases sensitivity. Here, we investigated this divergence in sensitivity by making direct neural measurements of responses to suprathreshold motion in human adults and 5-month-old infants using steady-state visually evoked potentials. Interocular differences in retinal image motion generated suppressed response functions and correspondingly elevated perceptual thresholds compared to motion matched between the two eyes...
August 29, 2018: Nature Communications
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