scholarly journals Physiological Properties of Rod Photoreceptor Cells in Green-sensitive Cone Pigment Knock-in Mice

2007 ◽  
Vol 130 (1) ◽  
pp. 21-40 ◽  
Author(s):  
Keisuke Sakurai ◽  
Akishi Onishi ◽  
Hiroo Imai ◽  
Osamu Chisaka ◽  
Yoshiki Ueda ◽  
...  
Keyword(s):  
Visual Pigment ◽  
Single Photon ◽  
Noise Analysis ◽  
Photoreceptor Cells ◽  
Molecular Properties ◽  
Rod Photoreceptor ◽  
Wild Type ◽  
Scotopic Vision ◽  
Signal Transduction Proteins ◽  
Single Photon Response

Rod and cone photoreceptor cells that are responsible for scotopic and photopic vision, respectively, exhibit photoresponses different from each other and contain similar phototransduction proteins with distinctive molecular properties. To investigate the contribution of the different molecular properties of visual pigments to the responses of the photoreceptor cells, we have generated knock-in mice in which rod visual pigment (rhodopsin) was replaced with mouse green-sensitive cone visual pigment (mouse green). The mouse green was successfully transported to the rod outer segments, though the expression of mouse green in homozygous retina was ∼11% of rhodopsin in wild-type retina. Single-cell recordings of wild-type and homozygous rods suggested that the flash sensitivity and the single-photon responses from mouse green were three to fourfold lower than those from rhodopsin after correction for the differences in cell volume and levels of several signal transduction proteins. Subsequent measurements using heterozygous rods expressing both mouse green and rhodopsin E122Q mutant, where these pigments in the same rod cells can be selectively irradiated due to their distinctive absorption maxima, clearly showed that the photoresponse of mouse green was threefold lower than that of rhodopsin. Noise analysis indicated that the rate of thermal activations of mouse green was 1.7 × 10−7 s−1, about 860-fold higher than that of rhodopsin. The increase in thermal activation of mouse green relative to that of rhodopsin results in only 4% reduction of rod photosensitivity for bright lights, but would instead be expected to severely affect the visual threshold under dim-light conditions. Therefore, the abilities of rhodopsin to generate a large single photon response and to retain high thermal stability in darkness are factors that have been necessary for the evolution of scotopic vision.

scholarly journals Temporal resolution of single-photon responses in primate rod photoreceptors and limits imposed by cellular noise

2019 ◽  
Vol 121 (1) ◽  
pp. 255-268 ◽  
Author(s):  
Greg D. Field ◽  
Valerie Uzzell ◽  
E. J. Chichilnisky ◽  
Fred Rieke
Keyword(s):  
Temporal Resolution ◽  
Moving Objects ◽  
Single Photon ◽  
Night Vision ◽  
Detection Sensitivity ◽  
Sensory Receptor ◽  
Rod Photoreceptor ◽  
Scotopic Vision ◽  
Central Processing ◽  
The Impact

Sensory receptor noise corrupts sensory signals, contributing to imperfect perception and dictating central processing strategies. For example, noise in rod phototransduction limits our ability to detect light, and minimizing the impact of this noise requires precisely tuned nonlinear processing by the retina. But detection sensitivity is only one aspect of night vision: prompt and accurate behavior also requires that rods reliably encode the timing of photon arrivals. We show here that the temporal resolution of responses of primate rods is much finer than the duration of the light response and identify the key limiting sources of transduction noise. We also find that the thermal activation rate of rhodopsin is lower than previous estimates, implying that other noise sources are more important than previously appreciated. A model of rod single-photon responses reveals that the limiting noise relevant for behavior depends critically on how rod signals are pooled by downstream neurons. NEW & NOTEWORTHY Many studies have focused on the visual system’s ability to detect photons, but not on its ability to encode the relative timing of detected photons. Timing is essential for computations such as determining the velocity of moving objects. Here we examine the timing precision of primate rod photoreceptor responses and show that it is more precise than previously appreciated. This motivates an evaluation of whether scotopic vision approaches limits imposed by rod temporal resolution.

Monte Carlo Simulation of Shot Noise Analysis for Reconstructing Elementary Events: Quantum Bumps in Photoreceptor Cells

1993 ◽  
Vol 48 (5-6) ◽  
pp. 519-528 ◽  
Author(s):  
Stephan Joeken ◽  
Jürgen Schnakenberg
Keyword(s):  
Experimental Data ◽  
Cell Membrane ◽  
Shot Noise ◽  
Single Channel ◽  
Single Photon ◽  
Noise Analysis ◽  
Photoreceptor Cells ◽  
High Light ◽  
Reconstruction Method ◽  
Light Intensities

Abstract Shot noise analysis is a frequently applied method for reconstructing elementary events from experimental data of noisy signals. The subject of this paper is the reconstruction of single photon responses in photoreceptors, the so-called quantum bumps, from experimental data which have been obtained at high light intensities where the quantum bumps can no longer be observed as individual events. The application of this method requires some basic prerequisites which are very likely not satisfied in photoreceptor cells. This situation makes the results of the method questionable. In order to estimate the reliability of shot noise reconstruc­tion in photoreceptors we directly compare the reconstruction results with well known input parameters by using a simulation model for the elementary mechanisms in the cell membrane which cause the response to light stimulation. The comparison shows that the reconstruction method starts to yield errors already at low intensities if only a few percent of the light con­ trolled ionic channels in the cell membrane are open on average. The errors of the method become about 100 percent in the light intensity regime between 10 percent open channels and the onset of bump speck contact on the membrane. The anticipation that the reconstruction method yields single channel events at high light intensities is disproved at least for physiologi­cally realistic intensities.

Ayurvedic management of Retinitis Pigmentosa (Doshandha) - A Case Study

2017 ◽  
Vol 2 (05) ◽  
Author(s):  
Anju D. ◽  
Pushpa Raj Poudel ◽  
Ajoy Viswam ◽  
Ashwini M. J.
Keyword(s):  
Retinitis Pigmentosa ◽  
Low Vision ◽  
Symptomatic Relief ◽  
Retinal Dystrophy ◽  
Treatment Protocol ◽  
Signs And Symptoms ◽  
Photoreceptor Cells ◽  
Rod Photoreceptor ◽  
Night Time ◽  
Initial Symptoms

Retinitis pigmentosa (RP) is an inherited, degenerative eye disease that causes severe vision impairment due to the progressive degeneration of rod photoreceptor cells in retina. This form of retinal dystrophy manifests initial symptoms independentof age; thus, RP diagnosis occurs anywhere from early infancy to late adulthood. This primary pigmentary retinal dystrophy is a hereditary disorder predominantly affecting the rods more than the cones. The main classical triads of retinitis pigmentosa are arteriolar attenuation, Retinal bone spicule pigmentation and Waxy disc pallor. The main treatment of retinitis pigmentosa is by using Low vision aids (LVA) and Genetic counseling. As such a complete cure for retinitis pigmentosa is not present. So a treatment protocol has to be adopted that helps in at least the symptomatic relief. In Ayurveda, the signs and symptoms of this can be compared with the Lakshanas of Doshandha which is one among the Dristigata Roga. It is considered as a diseased condition in which sunset will obliterate the Dristi Mandala and makes the person blind at night time. During morning hours the rising sunrays will disperse the accumulated Dosas from Dristi to clear vision. This disease resembles Kaphajatimira in its pathogenesis, but the night blindness is the special feature. Since the disease is purely Kaphaja, a treatment attempt is planned in Kaphara and Brimhana line. The present paper discusses a case of retinitis pigmentosa and it’s Ayurvedic Treatment.

scholarly journals Nano-optical single-photon response mapping of waveguide integrated molybdenum silicide (MoSi) superconducting nanowires

2016 ◽  
Vol 24 (13) ◽  
pp. 13931 ◽  
Author(s):  
Jian Li ◽  
Robert A. Kirkwood ◽  
Luke J. Baker ◽  
David Bosworth ◽  
Kleanthis Erotokritou ◽  
...  
Keyword(s):  
Single Photon ◽  
Molybdenum Silicide ◽  
Superconducting Nanowires ◽  
Response Mapping ◽  
Single Photon Response

scholarly journals Voltage-Dependent Calcium Channel CaV1.3 Subunits Regulate the Light Peak of the Electroretinogram

2007 ◽  
Vol 97 (5) ◽  
pp. 3731-3735 ◽  
Author(s):  
Jiang Wu ◽  
Alan D. Marmorstein ◽  
Jörg Striessnig ◽  
Neal S. Peachey
Keyword(s):  
Calcium Channel ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Rod Photoreceptor ◽  
Wild Type ◽  
Fast Oscillation ◽  
Light Peak ◽  
Voltage Dependent Calcium Channel ◽  
Voltage Dependent ◽  
Voltage Dependent Calcium Channels

In response to light, the mouse retinal pigment epithelium (RPE) generates a series of slow changes in potential that are referred to as the c-wave, fast oscillation (FO), and light peak (LP) of the electroretinogram (ERG). The LP is generated by a depolarization of the basolateral RPE plasma membrane by the activation of a calcium-sensitive chloride conductance. We have previously shown that the LP is reduced in both mice and rats by nimodipine, which blocks voltage-dependent calcium channels (VDCCs) and is abnormal in lethargic mice, carrying a null mutation in the calcium channel β4 subunit. To define the α1 subunit involved in this process, we examined mice lacking CaV1.3. In comparison with wild-type (WT) control littermates, LPs were reduced in CaV1.3−/− mice. This pattern matched closely with that previously noted in lethargic mice, confirming a role for VDCCs in regulating the signaling pathway that culminates in LP generation. These abnormalities do not reflect a defect in rod photoreceptor activity, which provides the input to the RPE to generate the c-wave, FO, and LP, because ERG a-waves were comparable in WT and CaV1.3−/− littermates. Our results identify CaV1.3 as the principal pore-forming subunit of VDCCs involved in stimulating the ERG LP.

Sign in / Sign up

Export Citation Format

Share Document