The influence of center-surround antagonism on light adaptation in cones in the retina of the turtle

1995 ◽  
Vol 12 (5) ◽  
pp. 877-885 ◽  
Author(s):  
Dwight A. Burkhardt
Keyword(s):  
Light Adaptation ◽  
Background Field ◽  
Light Sensitivity ◽  
Human Vision ◽  
Background Intensity ◽  
Test Flash ◽  
Cone Photoreceptors ◽  
Background Fields ◽  
Psychophysical Studies ◽  
Large Background

AbstractThe influence of center-surround antagonism on light adaptation in cone photoreceptors was investigated by intracellular recording from red-sensitive cones in the retina of the turtle, Pseudemys scripta elegans. Test flashes of 0.15-mm diameter were applied at the center of background fields of 0.25-mm or 2.2-mm diameter. Immediately upon expanding the background from 0.25 to 2.2 mm, the membrane potential depolarized by about 1–4 mV. The test flash response was enhanced if the depolarization was primarily due to synaptic feedback from horizontal cells, whereas the response was attenuated if the prolonged depolarization, an intrinsic response of the cone, was the dominant source of the depolarization. After several seconds, however, only the synaptic depolarization was maintained so maintained illumination of the large background field produced an enhancement of the cone's incremental sensitivity. The enhancement was examined in detail in steady-state conditions by obtaining amplitude-intensity measurements for centered test flashes on steady background fields over a large range of intensity. The effect of the large background field at any fixed intensity was fairly well described as a vertical (upward) shift of the amplitude-intensity curve obtained on the small field. This operation constitutes a quasi-subtractive mechanism of light adaptation and might provide a basis for the sort of subtractive mechanisms inferred from psychophysical studies of human vision. The enhancement was quantified by measuring the incremental sensitivity over four decades of background illumination. The magnitude of the enhancement increased with background intensity and then tended to stabilize at higher background intensities. The maximum difference in incremental sensitivity obtained on the large vs. small background field averaged 0.46 log unit (±0.12 s.d.). At higher background intensities, incremental sensitivity conformed to Weber's Law behavior about equally well for flashes applied on either small or large background fields. In sum, the present results provide evidence for an additional mechanism of light adaptation in cone photoreceptors by showing that the incremental light sensitivity, initially set by mechanisms in the outer segment, can be modulated some three-fold by synaptic feedback at the inner segment of the cone.

scholarly journals Light Adaptation in Pecten Hyperpolarizing Photoreceptors

1997 ◽  
Vol 109 (3) ◽  
pp. 371-384 ◽  
Author(s):  
Maria del Pilar Gomez ◽  
Enrico Nasi
Keyword(s):  
Light Adaptation ◽  
Light Sensitivity ◽  
Response Amplitude ◽  
Background Intensity ◽  
Sensory Receptor ◽  
Test Flash ◽  
Visual Response ◽  
Modulation Transfer ◽  
Stimulus Response ◽  
Underlying Mechanisms

The ability of scallop hyperpolarizing photoreceptors to respond without attenuation to repetitive flashes, together with their low light sensitivity, lack of resolvable quantum bumps and fast photoresponse kinetics, had prompted the suggestion that these cells may be constitutively in a state akin to light adaptation. We here demonstrate that their photocurrent displays all manifestations of sensory adaptation: (a) The response amplitude to a test flash is decreased in a graded way by background or conditioning lights. This attenuation of the response develops with a time constant of 200–800 ms, inversely related to background intensity. (b) Adapting stimuli shift the stimulus-response curve and reduce the size of the saturating photocurrent. (c) The fall kinetics of the photoresponse are accelerated by light adaptation, and the roll-off of the modulation transfer function is displaced to higher frequencies. This light-induced desensitization exhibits a rapid recovery, on the order of a few seconds. Based on the notion that Ca mediates light adaptation in other cells, we examined the consequences of manipulating this ion. Removal of external Ca reversibly increased the photocurrent amplitude, without affecting light sensitivity, photoresponse kinetics, or susceptibility to background adaptation; the effect, therefore, concerns ion permeation, rather than the regulation of the visual response. Intracellular dialysis with 10 mM BAPTA did not reduce the peak-to-plateau decay of the photocurrent elicited by prolonged light steps, not the background-induced compression of the response amplitude range and the acceleration of its kinetics. Conversely, high levels of buffered free [Ca]i (10 μM) only marginally shifted the sensitivity curve (Δσ = 0.3 log) and spared all manifestations of light adaptation. These results indicate that hyperpolarizing invertebrate photoreceptors adapt to light, but the underlying mechanisms must utilize pathways that are largely independent of changes in cytosolic Ca. The results are discussed in terms of aspects of commonalty to other ciliary sensory receptor cells.

scholarly journals MicroRNA Signatures of the Developing Primate Fovea

2021 ◽  
Vol 9 ◽  
Author(s):  
Elizabeth S. Fishman ◽  
Mikaela Louie ◽  
Adam M. Miltner ◽  
Simranjeet K. Cheema ◽  
Joanna Wong ◽  
...  
Keyword(s):  
Rhesus Monkey ◽  
Cell Fate ◽  
Molecular Mechanisms ◽  
Color Discrimination ◽  
Light Sensitivity ◽  
Human Vision ◽  
Mouse Retina ◽  
Mirna Cluster ◽  
Cone Photoreceptors ◽  
Specialized Region

Rod and cone photoreceptors differ in their shape, photopigment expression, synaptic connection patterns, light sensitivity, and distribution across the retina. Although rods greatly outnumber cones, human vision is mostly dependent on cone photoreceptors since cones are essential for our sharp visual acuity and color discrimination. In humans and other primates, the fovea centralis (fovea), a specialized region of the central retina, contains the highest density of cones. Despite the vast importance of the fovea for human vision, the molecular mechanisms guiding the development of this region are largely unknown. MicroRNAs (miRNAs) are small post-transcriptional regulators known to orchestrate developmental transitions and cell fate specification in the retina. Here, we have characterized the transcriptional landscape of the developing rhesus monkey retina. Our data indicates that non-human primate fovea development is significantly accelerated compared to the equivalent retinal region at the other side of the optic nerve head, as described previously. Notably, we also identify several miRNAs differentially expressed in the presumptive fovea, including miR-15b-5p, miR-342-5p, miR-30b-5p, miR-103-3p, miR-93-5p as well as the miRNA cluster miR-183/-96/-182. Interestingly, miR-342-5p is enriched in the nasal primate retina and in the peripheral developing mouse retina, while miR-15b is enriched in the temporal primate retina and increases over time in the mouse retina in a central-to-periphery gradient. Together our data constitutes the first characterization of the developing rhesus monkey retinal miRNome and provides novel datasets to attain a more comprehensive understanding of foveal development.

scholarly journals Action Spectra and Adaptation Properties of Carp Photoreceptors

1973 ◽  
Vol 61 (4) ◽  
pp. 401-423 ◽  
Author(s):  
P. Witkovsky ◽  
J. Nelson ◽  
H. Ripps
Keyword(s):  
Spectral Characteristics ◽  
Action Spectrum ◽  
Background Field ◽  
Ringer Solution ◽  
Test Flash ◽  
Negative Wave ◽  
Action Spectra ◽  
Threshold Functions ◽  
Background Fields ◽  
Bleaching Power

The mass photoreceptor response of the isolated carp retina was studied after immersing the tissue in aspartate-Ringer solution. Two electro-retinogram components were isolated by differential depth recording: a fast cornea-negative wave, arising in the receptor layer, and a slow, cornea-negative wave arising at some level proximal to the photoreceptors. Only the fast component was investigated further. In complete dark adaptation, its action spectrum peaked near 540 nm and indicated input from both porphyropsin-containing rods (λmax ≈ 525 nm) and cones with longer wavelength sensitivity. Under photopic conditions a broad action spectrum, λmax ≈ 580 nm was seen. In the presence of chromatic backgrounds, the photopic curve could be fractionated into three components whose action spectra agreed reasonably well with the spectral characteristics of blue, green, and red cone pigments of the goldfish. In parallel studies, the carp rod pigment was studied in situ by transmission densitometry. The reduction in optical density after a full bleach averaged 0.28 at its λmax 525 nm. In the isolated retina no regeneration of rod pigment occurred within 2 h after bleaching. The bleaching power of background fields used in adaptation experiments was determined directly. Both rods and cones generated increment threshold functions with slopes of +1 on log-log coordinates over a 3–4 log range of background intensities. Background fields which bleached less than 0.5% rod pigment nevertheless diminished photoreceptor sensitivity. The degree and rate of recovery of receptor sensitivity after exposure to a background field was a function of the total flux (I x t) of the field. Rod saturation, i.e. the abolition of rod voltages, occurred after ≈12% of rod pigment was bleached. In light-adapted retinas bathed in normal Ringer solution, a small test flash elicited a larger response in the presence of an annular background field than when it fell upon a dark retina. The enhancement was not observed in aspartate-treated retinas.

scholarly journals Two light-dependent conductances in Lima rhabdomeric photoreceptors.

1991 ◽  
Vol 97 (1) ◽  
pp. 55-72 ◽  
Author(s):  
E Nasi
Keyword(s):  
Light Adaptation ◽  
Late Phase ◽  
Reversal Potential ◽  
Membrane Conductance ◽  
Light Response ◽  
Light Sensitivity ◽  
Resting Potential ◽  
Test Flash ◽  
Ionic Selectivity ◽  
Subsequent Test

Light-dependent membrane currents were recorded from solitary Lima photoreceptors with the whole-cell clamp technique. Light stimulation from a holding voltage near the cell's resting potential evokes a transient inward current graded with light intensity, accompanied by an increase in membrane conductance. While the photocurrent elicited by dim flashes decays smoothly, at higher stimulus intensities two kinetically distinct components become visible. Superfusion with TEA or intracellular perfusion with Cs do not eliminate this phenomenon, indicating that it is not due to the activation of the Ca-sensitive K channels that are present in these cells. The relative amplitude of the late component vs. the early peak of the light response is significantly more pronounced at -60 mV than at -40 mV. At low light intensities the reversal potential of the photocurrent is around 0 mV, but with brighter lights no single reversal potential is found; rather, a biphasic response with an inward and an outward component can be seen within a certain range of membrane voltages. Light adaptation through repetitive stimulation with bright flashes diminishes the amplitude of the early but not the late phase of the photocurrent. These observations can be accounted for by postulating two separate light-dependent conductances with different ionic selectivity, kinetics, and light sensitivity. The light response is also shown to interact with some of the voltage-sensitive conductances: activation of the Ca current by a brief conditioning prepulse is capable of attenuating the photocurrent evoked by a subsequent test flash. Thus, Ca channels in these cells may not only shape the photoresponse, but also participate in the process of light adaptation.

scholarly journals Vortex Initialization in the NCEP Operational Hurricane Models

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 968
Author(s):  
Qingfu Liu ◽  
Xuejin Zhang ◽  
Mingjing Tong ◽  
Zhan Zhang ◽  
Bin Liu ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Background Field ◽  
Initial Field ◽  
The Future ◽  
Background Fields ◽  
Vortex Relocation ◽  
Hwrf Model ◽  
Vortex Initialization

This paper describes the vortex initialization (VI) currently used in NCEP operational hurricane models (HWRF and HMON, and possibly HAFS in the future). The VI corrects the background fields for hurricane models: it consists of vortex relocation, and size and intensity corrections. The VI creates an improved background field for the data assimilation and thereby produces an improved analysis for the operational hurricane forecast. The background field after VI can be used as an initial field (as in the HMON model, without data assimilation) or a background field for data assimilation (as in HWRF model).

Light adaptation and color opponency of horizontal cells in the turtle retina

2003 ◽  
Vol 20 (4) ◽  
pp. 437-452 ◽  
Author(s):  
GILAD TWIG ◽  
HANNA LEVY ◽  
ELITE WEINER ◽  
IDO PERLMAN
Keyword(s):  
Light Adaptation ◽  
Light Sensitivity ◽  
Horizontal Cells ◽  
Background Illumination ◽  
Voltage Range ◽  
Background Adaptation ◽  
Color Opponency ◽  
Light Stimuli ◽  
Type C

Chromaticity-type (C-type) horizontal cells of the turtle retina receive antagonistic inputs from cones of different spectral types, and therefore their response to background illumination is expected to reflect light adaptation of the cones and the interactions between their antagonistic inputs. Our goal was to study the behavior of C-type horizontal cells during background illumination and to evaluate the role of wavelength in background adaptation. The photoresponses of C-type horizontal cells were recorded intracellularly in the everted eyecup preparation of the turtleMauremys caspicaduring chromatic background illuminations. The voltage range of operation was either reduced or augmented, depending upon the wavelengths of the background and of the light stimuli, while the sensitivity to light was decreased by any background. The response–intensity curves were shifted to brighter intensities and became steeper as the background lights were made brighter regardless of wavelength. Comparing the effects of cone iso-luminant backgrounds on the Red/Green C-type horizontal cells indicated that background desensitization in these cells could not solely reflect background adaptation of cones but also depend upon response compression/expansion and changes in synaptic transmission. This leads to wavelength dependency of background adaptation in C-type horizontal cells, that is expressed as increased light sensitivity (smaller threshold elevation) and improved suprathreshold contrast detection when the wavelengths of the background and light stimuli were chosen to exert opponent effects on membrane potential.

A comparison of the components of the multifocal and full-field ERGs

1997 ◽  
Vol 14 (3) ◽  
pp. 533-544 ◽  
Author(s):  
Donald C. Hood ◽  
William Seiple ◽  
Karen Holopigian ◽  
Vivienne Greenstein
Keyword(s):  
Background Field ◽  
Multifocal Erg ◽  
Full Field ◽  
Input Parameters ◽  
Background Fields ◽  
Biphasic Responses

AbstractThe multi-input technique of Sutter and Tran (1992) yields multiple focal ERGs. The purpose here was to compare the components of this multifocal ERG to the components of the standard, full-field ERG. To record multifocal ERGs, an array of 103 hexagons was displayed on a monitor. Full-field (Ganzfeld) ERGs were elicited by flashes presented upon steady background fields. The latencies of two prominent subcomponents of the full-field ERG were altered by varying the intensity of the incremental flash or the intensity of the background field. By showing that similar manipulations of the multi-input parameters produce similar changes in latency, we were able to relate the components of the multifocal ERG to the components of the full-field ERG. The biphasic responses of the multifocal ERG appear to be generated by the same cells generating the a-wave and positive peaks of the full-field cone ERG.

The Influence of Solvents on the Fluorescence Background in Raman Spectroscopy

1987 ◽  
Vol 41 (3) ◽  
pp. 413-416 ◽  
Author(s):  
Sciichiro Higuchi ◽  
Er Jie Yu ◽  
Shigeyuki Tanaka
Keyword(s):  
Laser Irradiation ◽  
Raman Spectra ◽  
Aromatic Compounds ◽  
Irradiation Time ◽  
Polycyclic Aromatic Compounds ◽  
Background Intensity ◽  
Solvent Influence ◽  
Polycyclic Aromatic ◽  
Influence Of Solvents ◽  
Large Background

For the purpose of reducing the fluorescence background induced by the laser irradiation in the measurements of Raman spectra, the influence of solvents on the background intensities for three polycyclic aromatic compounds was examined, where the experiments were conducted with typical solvents. It was demonstrated that the behaviors of the fluorescence background against the laser irradiation time were quite different according to the solvents, and that the behaviors could be classified roughly into the three categories. It was proved that when suitable solvents were used, the background intensities could be reduced sufficiently, even for the fluorescent samples such as those treated here; thus, the clear observation of Raman spectra is obtained. As an example of the solvent influence on the Raman spectra, the results of measurements for three separate cases were shown for 1-nitropyrene. The three cases are as follows: first, the Raman bands are masked almost completely by the strong background (solvent: 1,1,2,2-tetrachloroethane); second, though the spectrum can be obtained, its S/N ratio is low because of the relatively large background (solvent: acetonitrile); third, a clear spectrum with excellent S/N ratio can be obtained because the background intensity is low enough (solvent: carbon tetrachloride).

scholarly journals EML1 (CNG-Modulin) Controls Light Sensitivity in Darkness and under Continuous Illumination in Zebrafish Retinal Cone Photoreceptors

2013 ◽  
Vol 33 (45) ◽  
pp. 17763-17776 ◽  
Author(s):  
J. I. Korenbrot ◽  
M. Mehta ◽  
N. Tserentsoodol ◽  
J. H. Postlethwait ◽  
T. I. Rebrik
Keyword(s):  
Light Sensitivity ◽  
Continuous Illumination ◽  
Cone Photoreceptors ◽  
Retinal Cone

Light-adaptation properties of the ultraviolet-sensitive cone mechanism in comparison to the other receptor mechanisms of goldfish

1991 ◽  
Vol 6 (4) ◽  
pp. 293-301 ◽  
Author(s):  
Craig W. Hawryshyn
Keyword(s):  
Heart Rate ◽  
Light Adaptation ◽  
Weber Fraction ◽  
Luminance Contrast ◽  
The Other ◽  
Brightness Contrast ◽  
Background Intensity ◽  
Contrast Threshold ◽  
Functional Differences ◽  
Threshold Technique

AbstractThe light-adaptation properties of goldfish photoreceptor mechanisms were examined using Stiles' two-color threshold technique. Threshold vs. background intensity (TVI) curves were determined for isolated cone and rod mechanisms using the heart-rate conditioning technique. The principal aim of this study was to compare the light-adaptation properties of the ultraviolet (UV)-sensitive cone mechanism to the other receptor mechanisms of goldfish. This examination revealed several striking functional differences: (1) The UV-sensitive cone mechanism threshold vs. background intensity (TVI) exhibited a slope of 0.65 (compared to the approximate 1.0 for the other cone mechanisms on a log/log plot) and thus was not in accordance with Weber's law. This may in part be related to the intrusion of the blue-sensitive mechanism at the upper radiance range. (2) The operation of the UV-sensitive cone mechanism was limited to intermediate intensities (i.e. not very dim or bright). (3) The UV-sensitive cone mechanism exhibited a Weber fraction or luminance contrast threshold of 0.316 that was approximately six times larger than the other cone mechanisms but comparable to the rod mechanism. This indicates that the UV-sensitive cone mechanism performs relatively poorly in terms of brightness contrast detection.

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