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1
CAMERON, DAVID A., and MAUREEN K. POWERS. "Morphology and visual pigment content of photoreceptors from injured goldfish retina." Visual Neuroscience 17, no. 4 (July 2000): 623–30. http://dx.doi.org/10.1017/s0952523800174115.
Повний текст джерелаАнотація:
Adult teleost fish retinas can regenerate neurons following either surgical or pharmacological injury. The cellular milieu of the damaged retina within which regenerated neurons are produced might be different in these two model systems of retinal injury, and thus the phenotypic attributes of regenerated neurons in the two model systems might also differ. To determine if the phenotypic attributes of photoreceptors, and by extension the recovery of vision, are different between these two model systems, we compared the visual pigment content and morphology of photoreceptors derived from goldfish retinas of both models with control retina. Visual pigments—which consist of a protein moiety (opsin) and a chromophore—were analyzed in single, isolated photoreceptors using microspectrophotometric techniques. We report that visual pigments and photoreceptor morphologies in the surgical model closely matched those of native retina. In contrast, neither photoreceptor morphology nor visual pigment content matched closely in the pharmacological model. The results indicate that phenotypic attributes of photoreceptors can differ significantly between the two model systems of retinal regeneration, but that in both systems, rod- and cone-mediated visual functions can potentially be reestablished.
2
Strauss, Olaf. "The Retinal Pigment Epithelium in Visual Function." Physiological Reviews 85, no. 3 (July 2005): 845–81. http://dx.doi.org/10.1152/physrev.00021.2004.
Повний текст джерелаАнотація:
Located between vessels of the choriocapillaris and light-sensitive outer segments of the photoreceptors, the retinal pigment epithelium (RPE) closely interacts with photoreceptors in the maintenance of visual function. Increasing knowledge of the multiple functions performed by the RPE improved the understanding of many diseases leading to blindness. This review summarizes the current knowledge of RPE functions and describes how failure of these functions causes loss of visual function. Mutations in genes that are expressed in the RPE can lead to photoreceptor degeneration. On the other hand, mutations in genes expressed in photoreceptors can lead to degenerations of the RPE. Thus both tissues can be regarded as a functional unit where both interacting partners depend on each other.
3
Frolov, Roman, Esa-Ville Immonen, and Matti Weckström. "Visual ecology and potassium conductances of insect photoreceptors." Journal of Neurophysiology 115, no. 4 (April 1, 2016): 2147–57. http://dx.doi.org/10.1152/jn.00795.2015.
Повний текст джерелаАнотація:
Voltage-activated potassium channels (Kv channels) in the microvillar photoreceptors of arthropods are responsible for repolarization and regulation of photoreceptor signaling bandwidth. On the basis of analyzing Kv channels in dipteran flies, it was suggested that diurnal, rapidly flying insects predominantly express sustained K+ conductances, whereas crepuscular and nocturnally active animals exhibit strongly inactivating Kv conductances. The latter was suggested to function for minimizing cellular energy consumption. In this study we further explore the evolutionary adaptations of the photoreceptor channelome to visual ecology and behavior by comparing K+ conductances in 15 phylogenetically diverse insects, using patch-clamp recordings from dissociated ommatidia. We show that rapid diurnal flyers such as the blowfly ( Calliphora vicina) and the honeybee ( Apis mellifera) express relatively large noninactivating Kv conductances, conforming to the earlier hypothesis in Diptera. Nocturnal and/or slow-moving species do not in general exhibit stronger Kv conductance inactivation in the physiological membrane voltage range, but the photoreceptors in species that are known to rely more on vision behaviorally had higher densities of sustained Kv conductances than photoreceptors of less visually guided species. No statistically significant trends related to visual performance could be identified for the rapidly inactivating Kv conductances. Counterintuitively, strong negative correlations were observed between photoreceptor capacitance and specific membrane conductance for both sustained and inactivating fractions of Kv conductance, suggesting insignificant evolutionary pressure to offset negative effects of high capacitance on membrane filtering with increased conductance.
4
Peirson, Stuart N., Stephanie Halford, and Russell G. Foster. "The evolution of irradiance detection: melanopsin and the non-visual opsins." Philosophical Transactions of the Royal Society B: Biological Sciences 364, no. 1531 (October 12, 2009): 2849–65. http://dx.doi.org/10.1098/rstb.2009.0050.
Повний текст джерелаАнотація:
Circadian rhythms are endogenous 24 h cycles that persist in the absence of external time cues. These rhythms provide an internal representation of day length and optimize physiology and behaviour to the varying demands of the solar cycle. These clocks require daily adjustment to local time and the primary time cue (zeitgeber) used by most vertebrates is the daily change in the amount of environmental light (irradiance) at dawn and dusk, a process termed photoentrainment. Attempts to understand the photoreceptor mechanisms mediating non-image-forming responses to light, such as photoentrainment, have resulted in the discovery of a remarkable array of different photoreceptors and photopigment families, all of which appear to use a basic opsin/vitamin A-based photopigment biochemistry. In non-mammalian vertebrates, specialized photoreceptors are located within the pineal complex, deep brain and dermal melanophores. There is also strong evidence in fish and amphibians for the direct photic regulation of circadian clocks in multiple tissues. By contrast, mammals possess only ocular photoreceptors. However, in addition to the image-forming rods and cones of the retina, there exists a third photoreceptor system based on a subset of melanopsin-expressing photosensitive retinal ganglion cells (pRGCs). In this review, we discuss the range of vertebrate photoreceptors and their opsin photopigments, describe the melanopsin/pRGC system in some detail and then finally consider the molecular evolution and sensory ecology of these non-image-forming photoreceptor systems.
5
Immonen, Esa-Ville, Irina Ignatova, Anna Gislen, Eric Warrant, Mikko Vähäsöyrinki, Matti Weckström, and Roman Frolov. "Large variation among photoreceptors as the basis of visual flexibility in the common backswimmer." Proceedings of the Royal Society B: Biological Sciences 281, no. 1795 (November 22, 2014): 20141177. http://dx.doi.org/10.1098/rspb.2014.1177.
Повний текст джерелаАнотація:
The common backswimmer, Notonecta glauca , uses vision by day and night for functions such as underwater prey animal capture and flight in search of new habitats. Although previous studies have identified some of the physiological mechanisms facilitating such flexibility in the animal's vision, neither the biophysics of Notonecta photoreceptors nor possible cellular adaptations are known. Here, we studied Notonecta photoreceptors using patch-clamp and intracellular recording methods. Photoreceptor size (approximated by capacitance) was positively correlated with absolute sensitivity and acceptance angles. Information rate measurements indicated that large and more sensitive photoreceptors performed better than small ones. Our results suggest that backswimmers are adapted for vision in both dim and well-illuminated environments by having open-rhabdom eyes with large intrinsic variation in absolute sensitivity among photoreceptors, exceeding those found in purely diurnal or nocturnal species. Both electrophysiology and microscopic analysis of retinal structure suggest two retinal subsystems: the largest peripheral photoreceptors provide vision in dim light and the smaller peripheral and central photoreceptors function primarily in sunlight, with light-dependent pigment screening further contributing to adaptation in this system by dynamically recruiting photoreceptors with varying sensitivity into the operational pool.
6
Chen, Pei-Ju, Gregor Belušič, and Kentaro Arikawa. "Chromatic information processing in the first optic ganglion of the butterfly Papilio xuthus." Journal of Comparative Physiology A 206, no. 2 (December 14, 2019): 199–216. http://dx.doi.org/10.1007/s00359-019-01390-w.
Повний текст джерелаАнотація:
AbstractThe butterfly Papilio xuthus has acute tetrachromatic color vision. Its eyes are furnished with eight spectral classes of photoreceptors, situated in three types of ommatidia, randomly distributed in the retinal mosaic. Here, we investigated early chromatic information processing by recording spectral, angular, and polarization sensitivities of photoreceptors and lamina monopolar cells (LMCs). We identified three spectral classes of LMCs whose spectral sensitivities corresponded to weighted linear sums of the spectral sensitivities of the photoreceptors present in the three ommatidial types. In ~ 25% of the photoreceptor axons, the spectral sensitivities differed from those recorded at the photoreceptor cell bodies. These axons showed spectral opponency, most likely mediated by chloride ion currents through histaminergic interphotoreceptor synapses. The opponency was most prominent in the processes of the long visual fibers in the medulla. We recalculated the wavelength discrimination function using the noise-limited opponency model to reflect the new spectral sensitivity data and found that it matched well with the behaviorally determined function. Our results reveal opponency at the first stage of Papilio’s visual system, indicating that spectral information is preprocessed with signals from photoreceptors within each ommatidium in the lamina, before being conveyed downstream by the long visual fibers and the LMCs.
7
van der Kooi, Casper J., Doekele G. Stavenga, Kentaro Arikawa, Gregor Belušič, and Almut Kelber. "Evolution of Insect Color Vision: From Spectral Sensitivity to Visual Ecology." Annual Review of Entomology 66, no. 1 (January 7, 2021): 435–61. http://dx.doi.org/10.1146/annurev-ento-061720-071644.
Повний текст джерелаАнотація:
Color vision is widespread among insects but varies among species, depending on the spectral sensitivities and interplay of the participating photoreceptors. The spectral sensitivity of a photoreceptor is principally determined by the absorption spectrum of the expressed visual pigment, but it can be modified by various optical and electrophysiological factors. For example, screening and filtering pigments, rhabdom waveguide properties, retinal structure, and neural processing all influence the perceived color signal. We review the diversity in compound eye structure, visual pigments, photoreceptor physiology, and visual ecology of insects. Based on an overview of the current information about the spectral sensitivities of insect photoreceptors, covering 221 species in 13 insect orders, we discuss the evolution of color vision and highlight present knowledge gaps and promising future research directions in the field.
8
Dalton, Brian E., Ellis R. Loew, Thomas W. Cronin, and Karen L. Carleton. "Spectral tuning by opsin coexpression in retinal regions that view different parts of the visual field." Proceedings of the Royal Society B: Biological Sciences 281, no. 1797 (December 22, 2014): 20141980. http://dx.doi.org/10.1098/rspb.2014.1980.
Повний текст джерелаАнотація:
Vision frequently mediates critical behaviours, and photoreceptors must respond to the light available to accomplish these tasks. Most photoreceptors are thought to contain a single visual pigment, an opsin protein bound to a chromophore, which together determine spectral sensitivity. Mechanisms of spectral tuning include altering the opsin, changing the chromophore and incorporating pre-receptor filtering. A few exceptions to the use of a single visual pigment have been documented in which a single mature photoreceptor coexpresses opsins that form spectrally distinct visual pigments, and in these exceptions the functional significance of coexpression is unclear. Here we document for the first time photoreceptors coexpressing spectrally distinct opsin genes in a manner that tunes sensitivity to the light environment. Photoreceptors of the cichlid fish, Metriaclima zebra , mix different pairs of opsins in retinal regions that view distinct backgrounds. The mixing of visual pigments increases absorbance of the corresponding background, potentially aiding the detection of dark objects. Thus, opsin coexpression may be a novel mechanism of spectral tuning that could be useful for detecting prey, predators and mates. However, our calculations show that coexpression of some opsins can hinder colour discrimination, creating a trade-off between visual functions.
9
Zheng, Lei, Gonzalo G. de Polavieja, Verena Wolfram, Musa H. Asyali, Roger C. Hardie, and Mikko Juusola. "Feedback Network Controls Photoreceptor Output at the Layer of First Visual Synapses in Drosophila." Journal of General Physiology 127, no. 5 (April 24, 2006): 495–510. http://dx.doi.org/10.1085/jgp.200509470.
Повний текст джерелаАнотація:
At the layer of first visual synapses, information from photoreceptors is processed and transmitted towards the brain. In fly compound eye, output from photoreceptors (R1–R6) that share the same visual field is pooled and transmitted via histaminergic synapses to two classes of interneuron, large monopolar cells (LMCs) and amacrine cells (ACs). The interneurons also feed back to photoreceptor terminals via numerous ligand-gated synapses, yet the significance of these connections has remained a mystery. We investigated the role of feedback synapses by comparing intracellular responses of photoreceptors and LMCs in wild-type Drosophila and in synaptic mutants, to light and current pulses and to naturalistic light stimuli. The recordings were further subjected to rigorous statistical and information-theoretical analysis. We show that the feedback synapses form a negative feedback loop that controls the speed and amplitude of photoreceptor responses and hence the quality of the transmitted signals. These results highlight the benefits of feedback synapses for neural information processing, and suggest that similar coding strategies could be used in other nervous systems.
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Ozaki, Ema, Luke Gibbons, Nuno GB Neto, Paul Kenna, Michael Carty, Marian Humphries, Pete Humphries, et al. "SARM1 deficiency promotes rod and cone photoreceptor cell survival in a model of retinal degeneration." Life Science Alliance 3, no. 5 (April 20, 2020): e201900618. http://dx.doi.org/10.26508/lsa.201900618.
Повний текст джерелаАнотація:
Retinal degeneration is the leading cause of incurable blindness worldwide and is characterised by progressive loss of light-sensing photoreceptors in the neural retina. SARM1 is known for its role in axonal degeneration, but a role for SARM1 in photoreceptor cell degeneration has not been reported. SARM1 is known to mediate neuronal cell degeneration through depletion of essential metabolite NAD and induction of energy crisis. Here, we demonstrate that SARM1 is expressed in photoreceptors, and using retinal tissue explant, we confirm that activation of SARM1 causes destruction of NAD pools in the photoreceptor layer. Through generation of rho−/−sarm1−/− double knockout mice, we demonstrate that genetic deletion of SARM1 promotes both rod and cone photoreceptor cell survival in the rhodopsin knockout (rho−/−) mouse model of photoreceptor degeneration. Finally, we demonstrate that SARM1 deficiency preserves cone visual function in the surviving photoreceptors when assayed by electroretinography. Overall, our data indicate that endogenous SARM1 has the capacity to consume NAD in photoreceptor cells and identifies a previously unappreciated role for SARM1-dependent cell death in photoreceptor cell degeneration.
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Yao, Xincheng, and Tae-Hoon Kim. "Fast intrinsic optical signal correlates with activation phase of phototransduction in retinal photoreceptors." Experimental Biology and Medicine 245, no. 13 (June 19, 2020): 1087–95. http://dx.doi.org/10.1177/1535370220935406.
Повний текст джерелаАнотація:
Quantitative assessment of physiological condition of retinal photoreceptors is desirable for better detection and treatment evaluation of eye diseases that can cause photoreceptor dysfunctions. Functional intrinsic optical signal (IOS) imaging, also termed as optoretinography (ORG) or optophysiology, has been proposed as a high-resolution method for objective assessment of retinal physiology. Fast IOS in retinal photoreceptors shows a time course earlier than that of electroretinography a-wave, promising an objective marker for noninvasive ORG of early phototransduction process in retinal photoreceptors. In this article, recent observations of fast photoreceptor-IOS in animal and human retinas are summarized, and the correlation of fast photoreceptor-IOS to five steps of phototransduction process is discussed. Transient outer segment conformational change, due to inter-disc space shrinkage correlated with activation phase of phototransduction, has been disclosed as a primary source of the fast photoreceptor-IOS. Impact statement As the center of phototransduction, retinal photoreceptors are responsible for capturing and converting photon energy to bioelectric signals for following visual information processing in the retina. This article summarizes experimental observation and discusses biophysical mechanism of fast photoreceptor-intrinsic optical signal (IOS) correlated with early phase of phototransduction. Quantitative imaging of fast photoreceptor-IOS may provide objective optoretinography to advance the study and diagnosis of age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy, and other eye diseases that can cause photoreceptor dysfunctions.
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Morera, Luis P., Nicolás M. Díaz, and Mario E. Guido. "Horizontal cells expressing melanopsin x are novel photoreceptors in the avian inner retina." Proceedings of the National Academy of Sciences 113, no. 46 (October 27, 2016): 13215–20. http://dx.doi.org/10.1073/pnas.1608901113.
Повний текст джерелаАнотація:
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. Here we investigate the intrinsic photosensitivity and functioning of HCs from primary cultures of embryonic retinas at day 15 by using calcium fluorescent fluo4 imaging, pharmacological inhibitory treatments, and Opn4x knockdown. Results show that HCs are avian photoreceptors with a retinal-based OPN4X photopigment conferring intrinsic photosensitivity. Light responses in HCs appear to be driven through an ancient type of phototransduction cascade similar to that in rhabdomeric photoreceptors involving a G-protein q, the activation of phospholipase C, calcium mobilization, and the release of the inhibitory neurotransmitter GABA. Based on their intrinsic photosensitivity, HCs may have a key dual function in the retina of vertebrates, potentially regulating nonvisual tasks together with their sister cells, ipRGCs, and with visual photoreceptors, modulating lateral interactions and retinal processing.
13
Grenell, Allison, Yekai Wang, Michelle Yam, Aditi Swarup, Tanya L. Dilan, Allison Hauer, Jonathan D. Linton, et al. "Loss of MPC1 reprograms retinal metabolism to impair visual function." Proceedings of the National Academy of Sciences 116, no. 9 (February 11, 2019): 3530–35. http://dx.doi.org/10.1073/pnas.1812941116.
Повний текст джерелаАнотація:
Glucose metabolism in vertebrate retinas is dominated by aerobic glycolysis (the “Warburg Effect”), which allows only a small fraction of glucose-derived pyruvate to enter mitochondria. Here, we report evidence that the small fraction of pyruvate in photoreceptors that does get oxidized by their mitochondria is required for visual function, photoreceptor structure and viability, normal neuron–glial interaction, and homeostasis of retinal metabolism. The mitochondrial pyruvate carrier (MPC) links glycolysis and mitochondrial metabolism. Retina-specific deletion of MPC1 results in progressive retinal degeneration and decline of visual function in both rod and cone photoreceptors. Using targeted-metabolomics and 13C tracers, we found that MPC1 is required for cytosolic reducing power maintenance, glutamine/glutamate metabolism, and flexibility in fuel utilization.
14
Sun, Ye, Zhiqiang Lin, Chi-Hsiu Liu, Yan Gong, Raffael Liegl, Thomas W. Fredrick, Steven S. Meng, et al. "Inflammatory signals from photoreceptor modulate pathological retinal angiogenesis via c-Fos." Journal of Experimental Medicine 214, no. 6 (May 2, 2017): 1753–67. http://dx.doi.org/10.1084/jem.20161645.
Повний текст джерелаАнотація:
Pathological neovessels growing into the normally avascular photoreceptors cause vision loss in many eye diseases, such as age-related macular degeneration and macular telangiectasia. Ocular neovascularization is strongly associated with inflammation, but the source of inflammatory signals and the mechanisms by which these signals regulate the disruption of avascular privilege in photoreceptors are unknown. In this study, we found that c-Fos, a master inflammatory regulator, was increased in photoreceptors in a model of pathological blood vessels invading photoreceptors: the very low-density lipoprotein receptor–deficient (Vldlr−/−) mouse. Increased c-Fos induced inflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor (TNF), leading to activation of signal transducer and activator of transcription 3 (STAT3) and increased TNFα–induced protein 3 (TNFAIP3) in Vldlr−/− photoreceptors. IL-6 activated the STAT3/vascular endothelial growth factor A (VEGFA) pathway directly, and elevated TNFAIP3 suppressed SOCS3 (suppressor of cytokine signaling 3)–activated STAT3/VEGFA indirectly. Inhibition of c-Fos using photoreceptor-specific AAV (adeno-associated virus)-hRK (human rhodopsin kinase)–sh_c-fos or a chemical inhibitor substantially reduced the pathological neovascularization and rescued visual function in Vldlr−/− mice. These findings suggested that the photoreceptor c-Fos controls blood vessel growth into the normally avascular photoreceptor layer through the inflammatory signal–induced STAT3/VEGFA pathway.
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Lee, Joo Yeun, Rachel A. Care, Luca Della Santina, and Felice A. Dunn. "Impact of Photoreceptor Loss on Retinal Circuitry." Annual Review of Vision Science 7, no. 1 (September 15, 2021): 105–28. http://dx.doi.org/10.1146/annurev-vision-100119-124713.
Повний текст джерелаАнотація:
Our sense of sight relies on photoreceptors, which transduce photons into the nervous system's electrochemical interpretation of the visual world. These precious photoreceptors can be disrupted by disease, injury, and aging. Once photoreceptors start to die, but before blindness occurs, the remaining retinal circuitry can withstand, mask, or exacerbate the photoreceptor deficit and potentially be receptive to newfound therapies for vision restoration. To maximize the retina's receptivity to therapy, one must understand the conditions that influence the state of the remaining retina. In this review, we provide an overview of the retina's structure and function in health and disease. We analyze a collection of observations on photoreceptor disruption and generate a predictive model to identify parameters that influence the retina's response. Finally, we speculate on whether the retina, with its remarkable capacity to function over light levels spanning nine orders of magnitude, uses these same adaptational mechanisms to withstand and perhaps mask photoreceptor loss.
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Fayzrakhmanov, R. R., and A. V. Sukhanova. "Foveal bulge as a predictor of high visual function in rhegmatogenous retinal detachment." Modern technologies in ophtalmology, no. 1 (May 29, 2021): 234–38. http://dx.doi.org/10.25276/2312-4911-2021-1-234-238.
Повний текст джерелаАнотація:
Introduction. The integrity of photoreceptor's inner segment/outer segment connection plays great importance in predicting visual acuity in eyes with retinal pathology. However, even optical coherence tomographic study showed the intact of retinal layers, including photoreceptor's inner segment/outer segment line, after surgery due to rhegmatogenous retinal detachment (RRD), low visual acuity is observed. Purpose. to identify predictors of high visual acuity in the foveolar zone in patients after successful RRD repair according to SD-OCT. Material and methods. Group 1 consisted of 20 cases – eyes after successful primary RRD repair performed through pars plana vitrectomy using silicone oil tamponade (1300 cSt), followed by removal of silicone oil with a replacement for sterile air. Group 2 – control, followed eyes without ophthalmopathology and visualisation of foveolar bulge according to OCT. All patients underwent a standard ophthalmological examination and OCT on the 30th day after silicone oil removal. OCT examination was performed by Retina Map and Cross Line modes. The lengths of the outer segments of photoreceptors, inner segments of photoreceptors and the outer nuclear layer of the layer were measured in manual mode. Retina Map was used to measure retinal foveolar thickness. Results. During the study, the data of the foveolar thickness of the retina, the outer nuclear layer and the length of the outer segment of photoreceptors in the main group showed a significant decrease in comparison with the control group (p=0.002, p=0.006, p=0.02, respectively). In this case, a strong correlation was obtained only between the length of the outer segments of photoreceptors and visual acuity (r=0.68). Conclusion. The length of the outer segments of the cones in the central retinal area, or foveolar bulge, should considers a predictor of high visual acuity twostage surgical treatment of primary RRD using silicone oil. Key words: retinal detachment, foveolar bulge, ellipsoid zone, vitrectomy, OCT.
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Kusakabe, Takehiro G., Noriko Takimoto, Minghao Jin, and Motoyuki Tsuda. "Evolution and the origin of the visual retinoid cycle in vertebrates." Philosophical Transactions of the Royal Society B: Biological Sciences 364, no. 1531 (October 12, 2009): 2897–910. http://dx.doi.org/10.1098/rstb.2009.0043.
Повний текст джерелаАнотація:
Absorption of a photon by visual pigments induces isomerization of 11- cis -retinaldehyde (RAL) chromophore to all- trans -RAL. Since the opsins lacking 11- cis -RAL lose light sensitivity, sustained vision requires continuous regeneration of 11- cis -RAL via the process called ‘visual cycle’. Protostomes and vertebrates use essentially different machinery of visual pigment regeneration, and the origin and early evolution of the vertebrate visual cycle is an unsolved mystery. Here we compare visual retinoid cycles between different photoreceptors of vertebrates, including rods, cones and non-visual photoreceptors, as well as between vertebrates and invertebrates. The visual cycle systems in ascidians, the closest living relatives of vertebrates, show an intermediate state between vertebrates and non-chordate invertebrates. The ascidian larva may use retinochrome-like opsin as the major isomerase. The entire process of the visual cycle can occur inside the photoreceptor cells with distinct subcellular compartmentalization, although the visual cycle components are also present in surrounding non-photoreceptor cells. The adult ascidian probably uses RPE65 isomerase, and trans -to- cis isomerization may occur in distinct cellular compartments, which is similar to the vertebrate situation. The complete transition to the sophisticated retinoid cycle of vertebrates may have required acquisition of new genes, such as interphotoreceptor retinoid-binding protein, and functional evolution of the visual cycle genes.
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Frolov, Roman, and Matti Weckström. "Developmental changes in biophysical properties of photoreceptors in the common water strider (Gerris lacustris): better performance at higher cost." Journal of Neurophysiology 112, no. 4 (August 15, 2014): 913–22. http://dx.doi.org/10.1152/jn.00239.2014.
Повний текст джерелаАнотація:
Although the dependence of invertebrate photoreceptor biophysical properties on visual ecology has already been investigated in some cases, developmental aspects have largely been ignored due to the general research emphasis on holometabolous insects. Here, using the patch-clamp method, we examined changes in biophysical properties and performance of photoreceptors in the common water strider Gerris lacustris during postembryonic development. We identified two types of peripheral photoreceptors, green and blue sensitive. Whole cell capacitance (a measure of cell size) of blue photoreceptors was significantly higher than the capacitance of green photoreceptors (69 ± 20 vs. 43 ± 12 pF, respectively). Most of the measured morphological and biophysical parameters changed with development. Photoreceptor capacitance increased progressively and was positively correlated with sensitivity to light, magnitudes and densities of light-induced (LIC) and delayed rectifier K+ ( IDR) currents, membrane corner frequency, and maximal information rate [Spearman rank correlation coefficients: 0.70 (sensitivity), 0.79 (LIC magnitude), 0.79 ( IDR magnitude), 0.48 (corner frequency), and 0.57 (information rate)]. Transient K+ current increased to a smaller extent, while its density decreased. We found no significant changes in the properties of single photon responses or levels of light-induced depolarization, the latter indicating a balanced channelome expansion associated with IDR expression. However, the dramatic ∼7.6-fold increase in IDR from first instars to adults indicated a development-related rise in the metabolic cost of information. In conclusion, this study provides novel insights into functional photoreceptor adaptations with development and illustrates remarkable variability in patterns of postembryonic retinal development in hemimetabolous insects with dissimilar visual ecologies and behaviors.
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Loew, E. R., V. I. Govardovskii, P. Röhlich, and Á. Szél. "Microspectrophotometric and immunocytochemical identification of ultraviolet photoreceptors in geckos." Visual Neuroscience 13, no. 2 (March 1996): 247–56. http://dx.doi.org/10.1017/s0952523800007483.
Повний текст джерелаАнотація:
AbstractRetinas of the nocturnal geckos, Hemidactylus turcicus, Hemidactylus garnotii, and Teratoscincus scincus, were studied with microspectrophotometry and immunocytochemistry against various visual pigment epitopes to reveal UV-sensitive photoreceptors. From 6–20% of the thinner members of type C double photoreceptors, earlier believed to be blue-sensitive, were found to contain a UV-absorbing visual pigment with λmax at 363–366 nm. The pigment had bleaching and dichroic properties typical of other photoreceptor cell types of the retina. Presumptive UV-sensitive cells in retinal sections were “negatively” labeled as they did not react with either the cone-specific monoclonal antibody COS-1 or with the anti-rhodopsin polyclonal serum AO, which together labeled all of the remaining photoreceptor types (green-sensitive A singles, B doubles, and thicker members of C doubles, as well as the blue-sensitive majority of thinner members of C doubles). UV cells were moderately stained with the mAb K42–41 produced against the 5–6 loop of bovine rhodopsin, which also moderately labeled blue-sensitive cells. mAb OS-2 strongly stained all outer segments, including the UV-sensitive ones. Similarities between gecko UV visual pigments, and UV visual pigments of other vertebrates, as well as possible functional significance of these cells are discussed.
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Simões, Bruno F., Filipa L. Sampaio, Ellis R. Loew, Kate L. Sanders, Robert N. Fisher, Nathan S. Hart, David M. Hunt, Julian C. Partridge, and David J. Gower. "Multiple rod–cone and cone–rod photoreceptor transmutations in snakes: evidence from visual opsin gene expression." Proceedings of the Royal Society B: Biological Sciences 283, no. 1823 (January 27, 2016): 20152624. http://dx.doi.org/10.1098/rspb.2015.2624.
Повний текст джерелаАнотація:
In 1934, Gordon Walls forwarded his radical theory of retinal photoreceptor ‘transmutation’. This proposed that rods and cones used for scotopic and photopic vision, respectively, were not fixed but could evolve into each other via a series of morphologically distinguishable intermediates. Walls' prime evidence came from series of diurnal and nocturnal geckos and snakes that appeared to have pure-cone or pure-rod retinas (in forms that Walls believed evolved from ancestors with the reverse complement) or which possessed intermediate photoreceptor cells. Walls was limited in testing his theory because the precise identity of visual pigments present in photoreceptors was then unknown. Subsequent molecular research has hitherto neglected this topic but presents new opportunities. We identify three visual opsin genes, rh1 , sws1 and lws , in retinal mRNA of an ecologically and taxonomically diverse sample of snakes central to Walls' theory. We conclude that photoreceptors with superficially rod- or cone-like morphology are not limited to containing scotopic or photopic opsins, respectively. Walls' theory is essentially correct, and more research is needed to identify the patterns, processes and functional implications of transmutation. Future research will help to clarify the fundamental properties and physiology of photoreceptors adapted to function in different light levels.
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Straiker, Alex, and Jane M. Sullivan. "Cannabinoid Receptor Activation Differentially Modulates Ion Channels in Photoreceptors of the Tiger Salamander." Journal of Neurophysiology 89, no. 5 (May 1, 2003): 2647–54. http://dx.doi.org/10.1152/jn.00268.2002.
Повний текст джерелаАнотація:
Cannabinoid CB1 receptors have been detected in retinas of numerous species, with prominent labeling in photoreceptor terminals of the chick and monkey. CB1 labeling is well-conserved across species, suggesting that CB1 receptors might also be present in photoreceptors of the tiger salamander. Synaptic transmission in vertebrate photoreceptors is mediated by L-type calcium currents—currents that are modulated by CB1 receptors in bipolar cells of the tiger salamander. Presence of CB1 receptors in photoreceptor terminals would therefore be consistent with presynaptic modulation of synaptic transmission, a role seen for cannabinoids in other parts of the brain. Here we report immunohistochemical and electrophysiological evidence for the presence of functional CB1 receptors in rod and cone photoreceptors of the tiger salamander. The cannabinoid receptor agonist WIN 55212-2 enhances calcium currents of rod photoreceptors by 39% but decreases calcium currents of large single cones by 50%. In addition, WIN 55212-2 suppresses potassium currents of rods and large single cones by 44 and 48%, respectively. Thus functional CB1 receptors, present in the terminals of rod and cone photoreceptors, differentially modulate calcium and potassium currents in rods and large single cones. CB1 receptors are therefore well positioned to modulate neurotransmitter release at the first synapse of the visual system.
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Sumner-Rooney, Lauren, Imran A. Rahman, Julia D. Sigwart, and Esther Ullrich-Lüter. "Whole-body photoreceptor networks are independent of ‘lenses’ in brittle stars." Proceedings of the Royal Society B: Biological Sciences 285, no. 1871 (January 24, 2018): 20172590. http://dx.doi.org/10.1098/rspb.2017.2590.
Повний текст джерелаАнотація:
Photoreception and vision are fundamental aspects of animal sensory biology and ecology, but important gaps remain in our understanding of these processes in many species. The colour-changing brittle star Ophiocoma wendtii is iconic in vision research, speculatively possessing a unique whole-body visual system that incorporates information from nerve bundles underlying thousands of crystalline ‘microlenses’. The hypothesis that these might form a sophisticated compound eye-like system regulated by chromatophores has been extensively reiterated, with investigations into biomimetic optics and similar supposedly ‘visual’ structures in living and fossil taxa. However, no photoreceptors or visual behaviours have ever been identified. We present the first evidence of photoreceptor networks in three Ophiocoma species, both with and without microlenses and colour-changing behaviour. High-resolution microscopy, immunohistochemistry and synchrotron tomography demonstrate that putative photoreceptors cover the animals' oral, lateral and aboral surfaces, but are absent at the hypothesized focal points of the microlenses. The structural optics of these crystal ‘lenses’ are an exaptation and do not fulfil any apparent visual role. This contradicts previous studies, yet the photoreceptor network in Ophiocoma appears even more widespread than previously anticipated, both taxonomically and anatomically.
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Guido, Mario. "Illuminating the Inner Retina of Vertebrates: Multiple Opsins and Non-Visual Photoreceptors." Science Reviews - from the end of the world 2, no. 1 (December 18, 2020): 7–17. http://dx.doi.org/10.52712/sciencereviews.v2i1.35.
Повний текст джерелаАнотація:
Throughout evolution, the need to detect light has generated highly specialized photoreceptor cells that in vertebrates are mainly located in the retina. The most studied photodetectors within these cells are the visual photoreceptors “cones and rods” responsible for day and night vision, respectively. These cells contain photosensitive molecules consisting of a protein part called “opsin” that binds a chromophore derived from vitamin A, retinaldehyde, capable of photoisomerizing from 11-cis retinal to all-trans retinal form, and triggering the light responses that lead to vision. However, other cells of the inner retina of vertebrates [retinal ganglion cells (RGCs), horizontal cells (HCs), and Muller’s glial cells] are currently known to express non-visual photopigments such as melanopsin (Opn4), encephalopsin (Opn3) and neuropsin (Opn5), which would be involved in diverse functions not associated with imaging. Melanopsin is the most widely studied of them, it is expressed in intrinsically photosensitive RGCs (ipRGCs) and HCs of the chicken retina and participates in setting the biological clock, the pupillary light reflex, and presumably in other reflex and subconscious functions, in addition to the lateral interaction between visual photoreceptors and HCs. It is noteworthy that these non-visual photopigments (Opn3, Opn4 and Opn5) respond to blue and/or near violet region light. This particular photosensitivity may provide individuals with a broader spectrum of response to light stimulation within the visible beyond the scope of the visual photoreceptors, regulating an important number of functions not yet completely identified. We can conclude that “a constellation of cells and photoreceptor molecules are present in the inner retina of vertebrates, and from very early stages of development, even before any sign of vision may occur.”
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Bara, Salvador, Maria Angeles Bonmati-Carrion, Juan Antonio Madrid, Maria Angeles Rol, and Jaime Zamorano. "Multispectral estimation of retinal photoreceptoral inputs." Photonics Letters of Poland 11, no. 3 (September 30, 2019): 60. http://dx.doi.org/10.4302/plp.v11i3.920.
Повний текст джерелаАнотація:
Integrated multispectral devices provide convenient means for assessing the inputs to the five known photoreceptors present in the human retina. These photoreceptors drive relevant visual and non-visual pathways that control key aspects of human physiology. In this Letter we show that standard metrics of retinal photoreceptoral exposure can be quantitatively estimated, to within a 5%, by means of 12 multispectral channels, 20 nm wide (FWHM), distributed across the visible range. Full Text: PDF ReferencesD.M. Berson, F.A. Dunn, M. Takao, "Phototransduction by Retinal Ganglion Cells That Set the Circadian Clock", Science 295, 1070 (2002). CrossRef R.J. Lucas et al. "Measuring and using light in the melanopsin age", Trends in Neurosciences 37, 1 (2014). CrossRef Commission Internationale de l'Eclairage. TN 003:2015 Report on the First International Workshop on Circadian and Neurophysiological Photometry, 2013. CIE, 2015. DirectLink A. Sánchez de Miguel et al, "Evaluating Human Photoreceptoral Inputs from Night-Time Lights Using RGB Imaging Photometry", Journal of Imaging 5(4), 49 (2019). CrossRef M.S. Rea, M.G. Figueiro, A. Bierman, R. Hamner. "Modelling the spectral sensitivity of the human circadian system", Lighting Research and Technology 44, 386 (2012). CrossRef D. Cao, P.A. Barrionuevo, "Estimating photoreceptor excitations from spectral outputs of a personal light exposure measurement device", Chronobiology International 32(2), 270 (2015). CrossRef P.B. Liebelt, An Introduction to Optimal Estimation (Reading, MA, Addison-Wesley, 1967). CrossRef J. Escofet, S. Bará, "Reducing the circadian input from self-luminous devices using hardware filters and software applications", Lighting Research and Technology 49, 481 (2017). CrossRef
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Juusola, Mikko, and Roger C. Hardie. "Light Adaptation in Drosophila Photoreceptors." Journal of General Physiology 117, no. 1 (December 12, 2000): 27–42. http://dx.doi.org/10.1085/jgp.117.1.27.
Повний текст джерелаАнотація:
It is known that an increase in both the mean light intensity and temperature can speed up photoreceptor signals, but it is not known whether a simultaneous increase of these physical factors enhances information capacity or leads to coding errors. We studied the voltage responses of light-adapted Drosophila photoreceptors in vivo from 15 to 30°C, and found that an increase in temperature accelerated both the phototransduction cascade and photoreceptor membrane dynamics, broadening the bandwidth of reliable signaling with an effective Q10 for information capacity of 6.5. The increased fidelity and reliability of the voltage responses was a result of four factors: (1) an increased rate of elementary response, i.e., quantum bump production; (2) a temperature-dependent acceleration of the early phototransduction reactions causing a quicker and narrower dispersion of bump latencies; (3) a relatively temperature-insensitive light-adapted bump waveform; and (4) a decrease in the time constant of the light-adapted photoreceptor membrane, whose filtering matched the dynamic properties of the phototransduction noise. Because faster neural processing allows faster behavioral responses, this improved performance of Drosophila photoreceptors suggests that a suitably high body temperature offers significant advantages in visual performance.
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Zhao, Meng, and Guang-Hua Peng. "Regulatory Mechanisms of Retinal Photoreceptors Development at Single Cell Resolution." International Journal of Molecular Sciences 22, no. 16 (August 4, 2021): 8357. http://dx.doi.org/10.3390/ijms22168357.
Повний текст джерелаАнотація:
Photoreceptors are critical components of the retina and play a role in the first step of the conversion of light to electric signals. With the discovery of the intrinsically photosensitive retinal ganglion cells, which regulate non-image-forming visual processes, our knowledge of the photosensitive cell family in the retina has deepened. Photoreceptor development is regulated by specific genes and proteins and involves a series of molecular processes including DNA transcription, post-transcriptional modification, protein translation, and post-translational modification. Single-cell sequencing is a promising technology for the study of photoreceptor development. This review presents an overview of the types of human photoreceptors, summarizes recent discoveries in the regulatory mechanisms underlying their development at single-cell resolution, and outlines the prospects in this field.
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Ogawa, Yuri, Marcin Falkowski, Ajay Narendra, Jochen Zeil, and Jan M. Hemmi. "Three spectrally distinct photoreceptors in diurnal and nocturnal Australian ants." Proceedings of the Royal Society B: Biological Sciences 282, no. 1808 (June 7, 2015): 20150673. http://dx.doi.org/10.1098/rspb.2015.0673.
Повний текст джерелаАнотація:
Ants are thought to be special among Hymenopterans in having only dichromatic colour vision based on two spectrally distinct photoreceptors. Many ants are highly visual animals, however, and use vision extensively for navigation. We show here that two congeneric day- and night-active Australian ants have three spectrally distinct photoreceptor types, potentially supporting trichromatic colour vision. Electroretinogram recordings show the presence of three spectral sensitivities with peaks ( λ max ) at 370, 450 and 550 nm in the night-active Myrmecia vindex and peaks at 370, 470 and 510 nm in the day-active Myrmecia croslandi . Intracellular electrophysiology on individual photoreceptors confirmed that the night-active M. vindex has three spectral sensitivities with peaks ( λ max ) at 370, 430 and 550 nm. A large number of the intracellular recordings in the night-active M. vindex show unusually broad-band spectral sensitivities, suggesting that photoreceptors may be coupled. Spectral measurements at different temporal frequencies revealed that the ultraviolet receptors are comparatively slow. We discuss the adaptive significance and the probability of trichromacy in Myrmecia ants in the context of dim light vision and visual navigation.
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Faivre, Olivier, and Mikko Juusola. "Visual Coding in Locust Photoreceptors." PLoS ONE 3, no. 5 (May 14, 2008): e2173. http://dx.doi.org/10.1371/journal.pone.0002173.
Повний текст джерела
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Pepe, I. M., I. Panfoli, and H. E. Hamm. "Visual transduction in vertebrate photoreceptors." Cell Biophysics 14, no. 2 (April 1989): 129–37. http://dx.doi.org/10.1007/bf02797130.
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D’Angelo, G. J., A. Glasser, M. Wendt, G. A. Williams, D. A. Osborn, G. R. Gallagher, R. J. Warren, K. V. Miller, and M. T. Pardue. "Visual specialization of an herbivore prey species, the white-tailed deer." Canadian Journal of Zoology 86, no. 7 (July 2008): 735–43. http://dx.doi.org/10.1139/z08-050.
Повний текст джерелаАнотація:
To gain knowledge of visual specializations influencing the behavior of white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)), we examined gross eye characteristics, structural organization of the retina, and the density and distribution of cone photoreceptors. White-tailed deer possess ocular features similar to other ungulates including a horizontal slit pupil, reflective tapetum lucidum, typical retinal structure, and medium wavelength sensitive cone photoreceptors concentrated in a horizontal visual streak. The tapetum was found to cover the superior portion of the eye and overlapped the horizontal visual streak. Comparisons between fawns and adults did not reveal any differences in retinal thickness, retinal nuclei counts, or cone photoreceptor counts. While M-cones had increased density in the visual streak, S-cones were distributed evenly across the entire retina. Schematic eye calculations of a 0.5-year-old deer indicated a hyperopic eye (+7.96) with a F/# ranging from 5.55 to 1.39 for pupil diameters of 3 to 12 mm. As expected for a crepuscularly active prey species, the visual system of white-tailed deer is specialized for sensitivity in low-light conditions and detection of predators.
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Frederiksen, Rikard, Nicholas P. Boyer, Benjamin Nickle, Kalyan S. Chakrabarti, Yiannis Koutalos, Rosalie K. Crouch, Daniel Oprian, and M. Carter Cornwall. "Low aqueous solubility of 11-cis-retinal limits the rate of pigment formation and dark adaptation in salamander rods." Journal of General Physiology 139, no. 6 (May 28, 2012): 493–505. http://dx.doi.org/10.1085/jgp.201110685.
Повний текст джерелаАнотація:
We report experiments designed to test the hypothesis that the aqueous solubility of 11-cis-retinoids plays a significant role in the rate of visual pigment regeneration. Therefore, we have compared the aqueous solubility and the partition coefficients in photoreceptor membranes of native 11-cis-retinal and an analogue retinoid, 11-cis 4-OH retinal, which has a significantly higher solubility in aqueous medium. We have then correlated these parameters with the rates of pigment regeneration and sensitivity recovery that are observed when bleached intact salamander rod photoreceptors are treated with physiological solutions containing these retinoids. We report the following results: (a) 11-cis 4-OH retinal is more soluble in aqueous buffer than 11-cis-retinal. (b) Both 11-cis-retinal and 11-cis 4-OH retinal have extremely high partition coefficients in photoreceptor membranes, though the partition coefficient of 11-cis-retinal is roughly 50-fold greater than that of 11-cis 4-OH retinal. (c) Intact bleached isolated rods treated with solutions containing equimolar amounts of 11-cis-retinal or 11-cis 4-OH retinal form functional visual pigments that promote full recovery of dark current, sensitivity, and response kinetics. However, rods treated with 11-cis 4-OH retinal regenerated on average fivefold faster than rods treated with 11-cis-retinal. (d) Pigment regeneration from recombinant and wild-type opsin in solution is slower when treated with 11-cis 4-OH retinal than with 11-cis-retinal. Based on these observations, we propose a model in which aqueous solubility of cis-retinoids within the photoreceptor cytosol can place a limit on the rate of visual pigment regeneration in vertebrate photoreceptors. We conclude that the cytosolic gap between the plasma membrane and the disk membranes presents a bottleneck for retinoid flux that results in slowed pigment regeneration and dark adaptation in rod photoreceptors.
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Jin, Jing, Gregor J. Jones, and M. Carter Cornwall. "Movement of retinal along cone and rod photoreceptors." Visual Neuroscience 11, no. 2 (March 1994): 389–99. http://dx.doi.org/10.1017/s0952523800001735.
Повний текст джерелаАнотація:
AbstractSingle isolated photoreceptors can be taken through a visual cycle of light adaptation by bleaching visual pigment, followed by dark adaptation when supplied with 11–cis retinal. Light adaptation after bleaching is manifested by faster response kinetics and a permanent reduction in sensitivity to light flashes, presumed to be due to the presence of bleached visual pigment. The recovery of flash sensitivity during dark adaptation is assumed to be due to regeneration of visual pigment to pre-bleach levels. In previous work, the outer segments of bleached, light-adapted cells were exposed to 11–cis retinal. In the present work, the cell bodies of bleached photoreceptors were exposed. We report a marked difference between rods and cones. Bleached cones recover sensitivity when their cell bodies are exposed to 11–cis retinal. Bleached rods do not. These results imply that retinal can move freely along the cone photoreceptor, but retinal either is not taken up by the rod cell body or retinal cannot move from the rod cell body to the rod outer segment. The free transfer of retinal along cone but not along rod photoreceptors could explain why, during dark adaptation in the retina, cones have access to a store of 11–cis retinal which is not available to rods. Additional experiments investigated the movement of retinal along bleached rod outer segments. The results indicate that retinal can move along the rod outer segment, but that this movement is slow, occurring at about the same rate as the regeneration of visual pigment.
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Procyk, Christopher A., Annette E. Allen, Franck P. Martial та Robert J. Lucas. "Visual responses in the dorsal lateral geniculate nucleus at early stages of retinal degeneration in rd1 PDE6β mice". Journal of Neurophysiology 122, № 4 (1 жовтня 2019): 1753–64. http://dx.doi.org/10.1152/jn.00231.2019.
Повний текст джерелаАнотація:
Inherited retinal degenerations encompass a wide range of diseases that result in the death of rod and cone photoreceptors, eventually leading to irreversible blindness. Low vision survives at early stages of degeneration, at which point it could rely on residual populations of rod/cone photoreceptors as well as the inner retinal photoreceptor, melanopsin. To date, the impact of partial retinal degeneration on visual responses in the primary visual thalamus (dorsal lateral geniculate nucleus, dLGN) remains unknown, as does their relative reliance on surviving rod and cone photoreceptors vs. melanopsin. To answer these questions, we recorded visually evoked responses in the dLGN of anesthetized rd1 mice using in vivo electrophysiology at an age (3–5 wk) at which cones are partially degenerate and rods are absent. We found that excitatory (ON) responses to light had lower amplitude and longer latency in rd1 mice compared with age-matched visually intact controls; however, contrast sensitivity and spatial receptive field size were largely unaffected at this early stage of degeneration. Responses were retained when those wavelengths to which melanopsin is most sensitive were depleted, indicating that they were driven primarily by surviving cones. Inhibitory responses appeared absent in the rd1 thalamus, as did light-evoked gamma oscillations in firing. This description of fundamental features of the dLGN visual response at this intermediate stage of retinal degeneration provides a context for emerging attempts to restore vision by introducing ectopic photoreception to the degenerate retina. NEW & NOTEWORTHY This study provides new therapeutically relevant insights to visual responses in the dorsal lateral geniculate nucleus during progressive retinal degeneration. Using in vivo electrophysiology, we demonstrate that visual responses have lower amplitude and longer latency during degeneration, but contrast sensitivity and spatial receptive fields remain unaffected. Such visual responses are driven predominantly by surviving cones rather than melanopsin photoreceptors. The functional integrity of this visual pathway is encouraging for emerging attempts at visual restoration.
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Kolesnikov, Alexander V., Tivadar Orban, Hui Jin, Celine Brooks, Lukas Hofmann, Zhiqian Dong, Maxim Sokolov, Krzysztof Palczewski, and Vladimir J. Kefalov. "Dephosphorylation by protein phosphatase 2A regulates visual pigment regeneration and the dark adaptation of mammalian photoreceptors." Proceedings of the National Academy of Sciences 114, no. 45 (October 23, 2017): E9675—E9684. http://dx.doi.org/10.1073/pnas.1712405114.
Повний текст джерелаАнотація:
Resetting of G-protein–coupled receptors (GPCRs) from their active state back to their biologically inert ground state is an integral part of GPCR signaling. This “on–off” GPCR cycle is regulated by reversible phosphorylation. Retinal rod and cone photoreceptors arguably represent the best-understood example of such GPCR signaling. Their visual pigments (opsins) are activated by light, transduce the signal, and are then inactivated by a GPCR kinase and arrestin. Although pigment inactivation by phosphorylation is well understood, the enzyme(s) responsible for pigment dephosphorylation and the functional significance of this reaction remain unknown. Here, we show that protein phosphatase 2A (PP2A) acts as opsin phosphatase in both rods and cones. Elimination of PP2A substantially slows pigment dephosphorylation, visual chromophore recycling, and ultimately photoreceptor dark adaptation. These findings demonstrate that visual pigment dephosphorylation regulates the dark adaptation of photoreceptors and provide insights into the role of this reaction in GPCR signaling.
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Palczewski, Krzysztof, and Philip D. Kiser. "Shedding new light on the generation of the visual chromophore." Proceedings of the National Academy of Sciences 117, no. 33 (August 5, 2020): 19629–38. http://dx.doi.org/10.1073/pnas.2008211117.
Повний текст джерелаАнотація:
The visual phototransduction cascade begins with acis–transphotoisomerization of a retinylidene chromophore associated with the visual pigments of rod and cone photoreceptors. Visual opsins release their all-trans-retinal chromophore following photoactivation, which necessitates the existence of pathways that produce 11-cis-retinal for continued formation of visual pigments and sustained vision. Proteins in the retinal pigment epithelium (RPE), a cell layer adjacent to the photoreceptor outer segments, form the well-established “dark” regeneration pathway known as the classical visual cycle. This pathway is sufficient to maintain continuous rod function and support cone photoreceptors as well although its throughput has to be augmented by additional mechanism(s) to maintain pigment levels in the face of high rates of photon capture. Recent studies indicate that the classical visual cycle works together with light-dependent processes in both the RPE and neural retina to ensure adequate 11-cis-retinal production under natural illuminances that can span ten orders of magnitude. Further elucidation of the interplay between these complementary systems is fundamental to understanding how cone-mediated vision is sustained in vivo. Here, we describe recent advances in understanding how 11-cis-retinal is synthesized via light-dependent mechanisms.
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ALLISON, W. TED, THEODORE J. HAIMBERGER, CRAIG W. HAWRYSHYN, and SHELBY E. TEMPLE. "Visual pigment composition in zebrafish: Evidence for a rhodopsin–porphyropsin interchange system." Visual Neuroscience 21, no. 6 (November 2004): 945–52. http://dx.doi.org/10.1017/s0952523804216145.
Повний текст джерелаАнотація:
Numerous reports have concluded that zebrafish (Danio rerio) possesses A1-based visual pigments in their rod and cone photoreceptors. In the present study, we investigated the possibility that zebrafish have a paired visual pigment system. We measured the spectral absorption characteristics of photoreceptors from zebrafish maintained in different temperature regimes and those treated with exogenous thyroid hormone using CCD-based microspectrophotometry. Rods from fish housed at 15°C and 28°C were not significantly different, having λmax values of 503 ± 5 nm (n = 106) and 504 ± 6 nm (n = 88), respectively. Thyroid hormone treatment (held at 28°C), however, significantly shifted the λmax of rods from 503 ± 5 nm (n = 194) to 527 ± 8 nm (n = 212). Cone photoreceptors in fish housed at 28°C (without thyroid hormone treatment) had λmax values of 361 ± 3 nm (n = 2) for ultraviolet-, 411 ± 5 nm (n = 18) for short-, 482 ± 6 nm (n = 9) for medium-, and 565 ± 10 nm (n = 14) for long-wavelength sensitive cones. Thyroid hormone treatment of fish held at 28°C significantly shifted the λmax of long-wavelength sensitive cones to 613 ± 11 nm (n = 20), substantially beyond that of the λmax of the longest possible A1-based visual pigment (∼580 nm). Thyroid hormone treatment produced smaller shifts of λmax in other cone types and increased the half-band width. All shifts in photoreceptor λmax values resulting from thyroid hormone treatment matched predictions for an A1- to A2-based visual pigment system. We therefore conclude that zebrafish possess a rhodopsin–porphyropsin interchange system that functions to spectrally tune rod and cone photoreceptors. We believe that these observations should be carefully considered during analysis of zebrafish spectral sensitivity.
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Kreysing, Moritz, Roland Pusch, Dorothee Haverkate, Meik Landsberger, Jacob Engelmann, Janina Ruiter, Carlos Mora-Ferrer, et al. "Photonic Crystal Light Collectors in Fish Retina Improve Vision in Turbid Water." Science 336, no. 6089 (June 28, 2012): 1700–1703. http://dx.doi.org/10.1126/science.1218072.
Повний текст джерелаАнотація:
Despite their diversity, vertebrate retinae are specialized to maximize either photon catch or visual acuity. Here, we describe a functional type that is optimized for neither purpose. In the retina of the elephantnose fish (Gnathonemus petersii), cone photoreceptors are grouped together within reflecting, photonic crystal–lined cups acting as macroreceptors, but rod photoreceptors are positioned behind these reflectors. This unusual arrangement matches rod and cone sensitivity for detecting color-mixed stimuli, whereas the photoreceptor grouping renders the fish insensitive to spatial noise; together, this enables more reliable flight reactions in the fish’s dim and turbid habitat as compared with fish lacking this retinal specialization.
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Evans, Barbara I., Ferenc I. Hárosi, and Russell D. Fernald. "Photoreceptor spectral absorbance in larval and adult winter flounder (Pseudopleuronectes americanus)." Visual Neuroscience 10, no. 6 (November 1993): 1065–71. http://dx.doi.org/10.1017/s0952523800010178.
Повний текст джерелаАнотація:
AbstractThe habitat occupied by larval winter flounder (Pseudopleuronectes americanus) differs considerably in light regime from that of the adult. To understand how the visual system has adapted to such changes, photoreceptor spectral absorbance was measured microspectrophotometrically in premetamorphic and postmetamorphic specimens of winter flounder. Before metamorphosis, larval flounder retinas contain only one kind of photoreceptor which is morphologically cone-like with peak absorbance at 519 nm. After metamorphosis, the adult retina has three types of photoreceptors: single cones, double cones, and rods. The visual pigment in single cones has a peak absorbance at λmax = 457 nm, the double cones at λmax = 531 and 547 nm, and the rod photoreceptors at λmax = 506 nm. Double cones were morphologically identical, but the two members contained either different (531/547 nm) or identical pigments (531/531 nm). The latter type were found only in the dorsal retina. The measured spectral half-bandwidths (HBW) were typical of visual pigments with chromophores derived from vitamin A1 with the possible exception of the long-wavelength absorbing pigment in double cones which appeared slightly broader. Because the premetamorphic pigment absorbance has a different λmax than those of the postmetamorphic pigments, different opsin genes must be expressed before and after metamorphosis.
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Pietra, Gianluca, Tiziana Bonifacino, Davide Talamonti, Giambattista Bonanno, Alessandro Sale, Lucia Galli, and Laura Baroncelli. "Visual Cortex Engagement in Retinitis Pigmentosa." International Journal of Molecular Sciences 22, no. 17 (August 30, 2021): 9412. http://dx.doi.org/10.3390/ijms22179412.
Повний текст джерелаАнотація:
Retinitis pigmentosa (RP) is a family of inherited disorders caused by the progressive degeneration of retinal photoreceptors. There is no cure for RP, but recent research advances have provided promising results from many clinical trials. All these therapeutic strategies are focused on preserving existing photoreceptors or substituting light-responsive elements. Vision recovery, however, strongly relies on the anatomical and functional integrity of the visual system beyond photoreceptors. Although the retinal structure and optic pathway are substantially preserved at least in early stages of RP, studies describing the visual cortex status are missing. Using a well-established mouse model of RP, we analyzed the response of visual cortical circuits to the progressive degeneration of photoreceptors. We demonstrated that the visual cortex goes through a transient and previously undescribed alteration in the local excitation/inhibition balance, with a net shift towards increased intracortical inhibition leading to improved filtering and decoding of corrupted visual inputs. These results suggest a compensatory action of the visual cortex that increases the range of residual visual sensitivity in RP.
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COLLIN, SHAUN P., NATHAN S. HART, JULIA SHAND, and IAN C. POTTER. "Morphology and spectral absorption characteristics of retinal photoreceptors in the southern hemisphere lamprey (Geotria australis)." Visual Neuroscience 20, no. 2 (March 2003): 119–30. http://dx.doi.org/10.1017/s0952523803202030.
Повний текст джерелаАнотація:
The morphology and spectral absorption characteristics of the retinal photoreceptors in the southern hemisphere lamprey Geotria australis (Agnatha) were studied using light and electron microscopy and microspectrophotometry. The retinae of both downstream and upstream migrants of Geotria contained two types of cone photoreceptor and one type of rod photoreceptor. Visual pigments contained in the outer segments of these three photoreceptor types had absorbance spectra typical of porphyropsins and with wavelengths of maximum absorbance (downstream/ upstream) at 610/616 nm (long-wavelength-sensitive cone, LWS), 515/515 nm (medium-wavelength-sensitive cone, MWS), and 506/500 nm (medium-wavelength-sensitive rod). A “yellow” photostable pigment was present in the myoid region of all three types of photoreceptor in the downstream migrant. The same short-wavelength-absorbing pigment, which prevents photostimulation of the beta band of the visual pigment in the outer segment, was present in the rods and LWS cones of the upstream migrant, but was replaced by a large transparent ellipsosome in the MWS cones. Using microspectrophotometric and anatomical data, the quantal spectral sensitivity of each photoreceptor type was calculated. Our results provide the first evidence of a jawless vertebrate, represented today solely by the lampreys and hagfishes, with two morphologically and physiologically distinct types of cone photoreceptors, in addition to a rod-like photoreceptor containing a colored filter (a cone-like characteristic). In contrast, all other lampreys studied thus far have either (1) one type of cone and one type of rod, or (2) a single type of rod-like photoreceptor.
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Lessios, Nicolas. "Using electroretinograms and multi-model inference to identify spectral classes of photoreceptors and relative opsin expression levels." PeerJ 5 (July 21, 2017): e3595. http://dx.doi.org/10.7717/peerj.3595.
Повний текст джерелаАнотація:
Understanding how individual photoreceptor cells factor in the spectral sensitivity of a visual system is essential to explain how they contribute to the visual ecology of the animal in question. Existing methods that model the absorption of visual pigments use templates which correspond closely to data from thin cross-sections of photoreceptor cells. However, few modeling approaches use a single framework to incorporate physical parameters of real photoreceptors, which can be fused, and can form vertical tiers. Akaike’s information criterion (AICc) was used here to select absorptance models of multiple classes of photoreceptor cells that maximize information, given visual system spectral sensitivity data obtained using extracellular electroretinograms and structural parameters obtained by histological methods. This framework was first used to select among alternative hypotheses of photoreceptor number. It identified spectral classes from a range of dark-adapted visual systems which have between one and four spectral photoreceptor classes. These were the velvet worm,Principapillatus hitoyensis, the branchiopod water flea,Daphnia magna, normal humans, and humans with enhanced S-cone syndrome, a condition in which S-cone frequency is increased due to mutations in a transcription factor that controls photoreceptor expression. Data from the Asian swallowtail,Papilio xuthus, which has at least five main spectral photoreceptor classes in its compound eyes, were included to illustrate potential effects of model over-simplification on multi-model inference. The multi-model framework was then used with parameters of spectral photoreceptor classes and the structural photoreceptor array kept constant. The goal was to map relative opsin expression to visual pigment concentration. It identified relative opsin expression differences for two populations of the bluefin killifish,Lucania goodei. The modeling approach presented here will be useful in selecting the most likely alternative hypotheses of opsin-based spectral photoreceptor classes, using relative opsin expression and extracellular electroretinography.
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Tao, Ye, Lei Ding, Anhui Yao, Zhen Yang, Qinghua Yang, Limin Qin, Linjun Yu та ін. "Intravitreous Delivery of Αb-Crystallin Ameliorates N-Methyl-N-Nitrosourea Induced Photoreceptor Degeneration in Mice: An in vivo and ex vivo Study". Cellular Physiology and Biochemistry 48, № 5 (2018): 2147–60. http://dx.doi.org/10.1159/000492557.
Повний текст джерелаАнотація:
Background/Aims: αB –crystallin (αBC) belongs to the family of small heat shock proteins that are necessary for maintaining oxygen homeostasis. This study was designed to explore the possible effects of αBC on N-methyl- N-nitrosourea (MNU) induced retinal degeneration and the underlying mechanisms. Methods: The αBC was injected into the vitreous bodies of MNU administered mice. The retinal morphology and visual function of experimental animals were analyzed by electroretinography (ERG), Spectral domain optical coherence tomography (SD-OCT), fundus photographs, optokinetic testing and immunohistochemistry assay. Results: Optokinetic behavioural tests and ERG examination suggested that the visual impairments of the MNU administered mice were ameliorated effectively by αBC treatment. OCT analysis showed that the major retinal architecture of the MNU administered mice was efficiently rescued by αBC treatment. Fundus examination suggested that the lesion size of the MNU administered mice was decreased by αBC treatment. MNU induced photoreceptor loss was also mitigated by αBC treatment as shown by hematoxylin and eosin staining. In particular, the immunostaining study suggested that M-cone photoreceptors, rather than the S-cone photoreceptors, were preferentially rescued, indicating that the photoreceptor populations have different sensitivities to αBC. The mechanism study suggested that the anti-apoptotic, anti-oxidative and neurotrophic function of αBC collectively contributed to these therapeutic effects. Conclusion: Intravitreal delivery of αBC could alleviate MNU induced photoreceptor degeneration and visual impairment. Further refinement of the αBC induced protection would afford a novel therapeutic strategy for retinitis pigmentosa.
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Ignatova, Irina I., Paulus Saari, and Roman V. Frolov. "Latency of phototransduction limits transfer of higher-frequency signals in cockroach photoreceptors." Journal of Neurophysiology 123, no. 1 (January 1, 2020): 120–33. http://dx.doi.org/10.1152/jn.00365.2019.
Повний текст джерелаАнотація:
Visual transduction in rhabdomeric photoreceptors is compartmentalized and discretized. Signals of individual microvilli, the quantum bumps, are electrotonically summed, producing a graded response. Intrinsic dispersion of quantum bump latencies is thought to introduce noise and degrade signal transfer. Here, we found profound differences in the information rate and signaling bandwidth between in vitro patch-clamp and in vivo intracellular recordings of Periplaneta americana photoreceptors and traced them to the properties of quantum bumps and membrane resistance. Comparison of macroscopic and elementary light responses revealed differences in quantum bump summation and membrane resistance in vivo versus in vitro. Modeling of voltage bumps suggested that current bumps in vivo should be much bigger and faster than those actually recorded in vitro. Importantly, the group-average latency of dark-adapted photoreceptors was 30 ± 8 ms in intracellular ( n = 34) versus 70 ± 19 ms in patch-clamp ( n = 57) recordings. Duration of composite responses increased with mean latency because bump dispersion depended on mean latency. In vivo, latency dispersion broadened the composite response by 25% on average and slowed its onset. However, in the majority of photoreceptors, the characteristic durations of multiphoton impulse responses to 1-ms stimuli did not exceed the durations of mean voltage bumps. Consistently, we found strong associations between the latency and onset kinetics of the macroscopic response, on the one hand and the higher-frequency signal gain and information rate of the photoreceptor, on the other hand, indicating a direct connection between quantum bump latency and its dispersion and the signaling bandwidth. NEW & NOTEWORTHY When stimulated by light, microvilli of rhabdomeric photoreceptors produce discrete signals characterized by variable latencies. We show that this intrinsic latency dispersion restricts signaling bandwidth and information rate of photoreceptors in Periplaneta americana. Profound differences are found between the properties of photoreceptor responses in vivo and in vitro.
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Shantha, Jessica G., Gregg T. Kokame, and Lucas Kim. "Recurrent Photoreceptor Loss with Spontaneous Recovery as a Presenting Sign of Syphilitic Outer Retinopathy." Open Ophthalmology Journal 13, no. 1 (December 20, 2019): 86–89. http://dx.doi.org/10.2174/1874364101913010086.
Повний текст джерелаАнотація:
A 64-year-old male presented with sudden onset of decreased vision with a central blind spot and shimmering visual symptoms without significant inflammatory findings, and was noted on optical coherence tomography to have localized loss of photoreceptors, which spontaneously resolved after two weeks. This recurred subsequently three times spaced by months of recovery with normal vision and normal photoreceptors. In the fourth episode, the patient developed an arcuate-shaped area of outer retinitis more typical for acute syphilitic posterior placoid chorioretinitis, and the diagnosis was made serologically. With subsequent treatment for syphilis, there was not any recurrence after the treatment and vision recovered to 20/20 with a normal photoreceptor layer.
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Lythgoe, J. N., and J. C. Partridge. "Visual pigments and the acquisition of visual information." Journal of Experimental Biology 146, no. 1 (September 1, 1989): 1–20. http://dx.doi.org/10.1242/jeb.146.1.1.
Повний текст джерелаАнотація:
All the information available to the brain for the interpretation of the visual scene comes from the number of photons absorbed by a very limited number of photoreceptor types which are characterized by their spectral sensitivity. In vertebrates there are considerable differences in the spectral absorption of the rods and cones making up the retinal mosaic of different animals and, in some cases, including fish and primates, there are considerable differences between the cone sets of individuals within a species. Broadly speaking, the spectral sensitivity of the photoreceptors is related to the spectral distribution of the ambient light and this is particularly true of the colour-biased light under water. When an animal migrates from one visual environment to another, its cone complement may change to that suited to the new conditions. However, significant differences between the cone sets of animals living within the same environment and colour vision polymorphism within a species suggest that visual tasks critical to survival or breeding success require particular visual pigment sets. A start has been made in trying to understand what tasks are best served by different pigment sets.
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Ignatova, Irina I., Andrew S. French, and Roman V. Frolov. "Effects of phase correlations in naturalistic stimuli on quantitative information coding by fly photoreceptors." Journal of Neurophysiology 119, no. 6 (June 1, 2018): 2276–90. http://dx.doi.org/10.1152/jn.00017.2018.
Повний текст джерелаАнотація:
Natural visual scenes are rarely random. Instead, intensity and wavelength change slowly in time and space over many regions of the scene, so that neighboring temporal and spatial visual inputs are more correlated and contain less information than truly random signals. It has been suggested that sensory optimization to match these higher order correlations (HOC) occurs at the earliest visual stages, and that photoreceptors can process temporal natural signals more efficiently than random signals. We tested this early-stage hypothesis by comparing the information content of Calliphora vicina photoreceptor responses to naturalistic inputs before and after removing HOC by randomizing phase. Forty different, 60-s long, naturalistic sequences (NS) were used, together with randomized-phase versions of the same sequences to give pink noise (PN) so that each input pair had identical means, variances, mean contrasts, and power spectra. We measured the information content of inputs and membrane potential responses by three different methods: coherence, mutual information, and compression entropy. We also used entropy and phase statistics of each pair as measures of HOC. Responses to randomized signals generally had higher gain, signal-to-noise ratio, and information rates than responses to NS. Information rate increased with a strong, positive, linear correlation to phase randomization within sequence pairs. This was confirmed by varying the degree of phase randomization. Our data indicate that individual photoreceptors encode input information by Weber’s law, with HOC within natural sequences reducing information transfer by decreasing the number of local contrast events that exceed the noise-imposed threshold. NEW & NOTEWORTHY Natural visual scenes feature statistical regularities, or higher order correlations (HOC), both in time and space, to encode surfaces, textures, and object boundaries. Visual systems rely on this information; however, it remains controversial whether individual photoreceptors can discriminate and enhance information encoded in HOC. Here we show that the more HOC the stimulus contains, the lower the information transfer rate of photoreceptors. We explain our findings by applying the Weber’s paradigm of differential signal perception.
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Li, Jinying, Chen Qiu, Jiayi Zhou, Yang Wei, Weixin Yuan, Jia Liu, Wenyu Cui, et al. "Repair of Retinal Degeneration by Human Amniotic Epithelial Stem Cell–Derived Photoreceptor–like Cells." International Journal of Molecular Sciences 23, no. 15 (August 5, 2022): 8722. http://dx.doi.org/10.3390/ijms23158722.
Повний текст джерелаАнотація:
The loss of photoreceptors is a major event of retinal degeneration that accounts for most cases of untreatable blindness globally. To date, there are no efficient therapeutic approaches to treat this condition. In the present study, we aimed to investigate whether human amniotic epithelial stem cells (hAESCs) could serve as a novel seed cell source of photoreceptors for therapy. Here, a two–step treatment with combined Wnt, Nodal, and BMP inhibitors, followed by another cocktail of retinoic acid, taurine, and noggin induced photoreceptor–like cell differentiation of hAESCs. The differentiated cells demonstrated the morphology and signature marker expression of native photoreceptor cells and, intriguingly, bore very low levels of major histocompatibility complex (MHC) class II molecules and a high level of non–classical MHC class I molecule HLA–G. Importantly, subretinal transplantation of the hAESCs–derived PR–like cells leads to partial restoration of visual function and retinal structure in Royal College of Surgeon (RCS) rats, the classic preclinical model of retinal degeneration. Together, our results reveal hAESCs as a potential source of functional photoreceptor cells; the hAESCs–derived photoreceptor–like cells could be a promising cell–replacement candidate for therapy of retinal degeneration diseases.
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Grzywacz, Norberto M., Franklin R. Amthor, and David K. Merwine. "Directional hyperacuity in ganglion cells of the rabbit retina." Visual Neuroscience 11, no. 5 (September 1994): 1019–25. http://dx.doi.org/10.1017/s0952523800003953.
Повний текст джерелаАнотація:
AbstractBiological visual systems can detect positional changes that are finer than these systems' acuity to sine-wave gratings, a property known as hyperacuity. Some systems can even detect changes finer that the photoreceptor spacing. We report here that rabbit's directionally selective ganglion cells not only detect positional changes in the hyperacuity range, but also discriminate the direction of their motion. Our experiments show that directional selectivity occurs for edges of light moving as little as 1.1 μm (26” of visual angle) across the retina. This distance corresponds to a hyperacuity, since the acuity to sine-wave gratings of rabbit's On-Off DS ganglion cells is about 125 μm (50′). In addition, this distance is smaller than the minimal spacing between rabbit photoreceptors (1.9 μm or 46”), as estimated from cell-density studies (Young & Vaney, 1991). Such a hyperacuity suggests low-noise high-gain signal transmission from photoreceptors to ganglion cells and that directional selectivity can arise in small portions of retinal dendritic processes.
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Simmons, P. "The transfer of signals from photoreceptor cells to large second-order neurones in the ocellar visual system of the locust Locusta migratoria." Journal of Experimental Biology 198, no. 2 (February 1, 1995): 537–49. http://dx.doi.org/10.1242/jeb.198.2.537.
Повний текст джерелаАнотація:
The operation of the first synapse in the ocellar pathway of the locust Locusta migratoria has been studied by making simultaneous intracellular recordings from photoreceptors and large, second-order L-neurones. 1. The transfer curve for the synapse, obtained by plotting the amplitudes of the initial peak responses by the two cells to pulses of light against each other, shows that L-neurones are extremely sensitive to changes in photoreceptor potential and that the connection is tonically active in darkness. 2. Postsynaptic current in an L-neurone, produced when pulses of light are delivered from a dark background, saturates at a slightly brighter light intensity than does the postsynaptic potential. 3. The signal-to-noise ratio improves with increases in light intensity in both cells, but the reduction in noise as signals are transmitted from photoreceptors to L-neurones is less than would be expected from the number of photoreceptors that probably converge on each L-neurone. 4. In both cells, in the presence of different intensities of background illumination, the slope of the intensity­response curve is maintained as the curve moves along the light intensity axis. Adaptation is relatively slow so that, at least for several minutes after an increase in background illumination, both cells maintain a sustained response and the responses to stimuli of increased illumination are reduced in amplitude. During sustained background illumination, the transfer curve for the synapse between a photoreceptor and an L-neurone shifts along both axes without a change in its maximum slope. 5. The slope of the synaptic transfer curve depends on the speed as well as the amplitude of changes in light. 6. In response to injection of depolarising pulses of current into a photoreceptor, an L-neurone generates brief, hyperpolarising responses. The amplitude of the responses depends on the strength and speed of the depolarising stimuli. After an initial response by an L-neurone, subsequent responses are reduced in amplitude for 200 ms. 7. The amplitude of L-neurone responses to electrical stimulation of a photoreceptor increases when the hyperpolarising constant current is injected into the photoreceptor.
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Hart, Nathan S. "The Visual Ecology of Avian Photoreceptors." Progress in Retinal and Eye Research 20, no. 5 (September 2001): 675–703. http://dx.doi.org/10.1016/s1350-9462(01)00009-x.
Повний текст джерела