Position of rhodopsin photoisomerization on the disk surface confers variability to the rising phase of the single photon response in vertebrate rod photoreceptors

Our ability to see in dim light is limited by the statistics of light absorption in rod photoreceptors and the faithful transmission of the light-evoked signals through the retina. This article reviews the physiological mechanisms at the synapse between rods and rod bipolar cells, the first relay in a pathway that mediates vision near absolute threshold.

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Properties of multi-vesicular release from rod photoreceptors support transmission of single photon responses

10.1101/2021.02.01.429179 ◽

2021 ◽

Cited By ~ 2

Author(s):

CL Hays ◽

AL Sladek ◽

GD Field ◽

WB Thoreson

Keyword(s):

Poisson Process ◽

Single Photon ◽

Glutamate Release ◽

Bipolar Cells ◽

Resting Membrane Potential ◽

Rod Photoreceptors ◽

Voltage Change ◽

Single Photon Response ◽

Rebound Increase ◽

Stimulus Offset

AbstractVision under starlight requires rod photoreceptors to transduce and transmit single photon responses to the visual system. This remarkable sensitivity depends on a small voltage change reliably reducing glutamate release such that post-synaptic rod bipolar cells can robustly detect the signal. To transmit this small signal, we have found that rod vesicle release deviates strongly from a Poisson process under conditions that mimic darkness. Specifically, at their resting membrane potential in darkness, rods exhibit coordinated and regularly timed multivesicular release events. Each release event consisted of ∼17 vesicles and occurred 2-3 times more regularly than expected from a Poisson process. Hyperpolarizing rods to mimic the voltage change produced by a single photon response abruptly reduced the probability of multivesicular release nearly to zero with a rebound increase in release probability at stimulus offset. Simulations of these release dynamics indicate that this regularly timed, multivesicular release promotes transmission of single photon responses to post-synaptic neurons. Furthermore, the mechanism is efficient, requiring fewer vesicles to be released per second than uniquantal release governed by Poisson statistics.

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

Optics Express ◽

10.1364/oe.24.013931 ◽

2016 ◽

Vol 24 (13) ◽

pp. 13931 ◽

Cited By ~ 17

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

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Diffusion of the Second Messengers in the Cytoplasm Acts as a Variability Suppressor of the Single Photon Response in Vertebrate Phototransduction

Biophysical Journal ◽

10.1529/biophysj.107.114058 ◽

2008 ◽

Vol 94 (9) ◽

pp. 3363-3383 ◽

Cited By ~ 30

Author(s):

Paolo Bisegna ◽

Giovanni Caruso ◽

Daniele Andreucci ◽

Lixin Shen ◽

Vsevolod V. Gurevich ◽

...

Keyword(s):

Single Photon ◽

Second Messengers ◽

Single Photon Response

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The discovery of the ability of rod photoreceptors to signal single photons

The Journal of General Physiology ◽

10.1085/jgp.201711970 ◽

2018 ◽

Vol 150 (3) ◽

pp. 383-388 ◽

Cited By ~ 10

Author(s):

Edward N. Pugh

Keyword(s):

Visual System ◽

Molecular Mechanism ◽

Single Photon ◽

Visual Environment ◽

Single Photons ◽

Rod Photoreceptors ◽

Subsequent Research ◽

Visual Threshold ◽

Reliable Transmission

Vertebrate rod photoreceptors evolved the astonishing ability to respond reliably to single photons. In parallel, the proximate neurons of the visual system evolved the ability to reliably encode information from a few single-photon responses (SPRs) as arising from the presence of an object of interest in the visual environment. These amazing capabilities were first inferred from measurements of human visual threshold by Hecht et al. (1942), whose paper has since been cited over 1,000 times. Subsequent research, in part inspired by Hecht et al.’s discovery, has directly measured rod SPRs, characterized the molecular mechanism responsible for their generation, and uncovered much about the specializations in the retina that enable the reliable transmission of SPRs in the teeth of intrinsic neuronal noise.

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Analytical Study of Front-End Circuits Coupled to Silicon Photomultipliers for Timing Performance Estimation under the Influence of Parasitic Components

Sensors ◽

10.3390/s20164428 ◽

2020 ◽

Vol 20 (16) ◽

pp. 4428

Author(s):

Pietro Antonio Paolo Calò ◽

Savino Petrignani ◽

Michele Di Gioia ◽

Cristoforo Marzocca

Keyword(s):

Single Photon ◽

Performance Estimation ◽

Laser Source ◽

Detector Response ◽

Silicon Photomultipliers ◽

Parasitic Inductance ◽

Front End ◽

Single Photon Response ◽

Variable Configuration ◽

Definition Of

Full exploitation of the intrinsic fast timing capabilities of analog silicon photomultipliers (SiPMs) requires suitable front-end electronics. Even a parasitic inductance of a few nH, associated to the interconnections between the SiPM and the preamplifier, can significantly degrade the steepness of the detector response, thus compromising the timing accuracy. In this work, we propose a simple analytic expression for the single-photon response of a SiPM coupled to the front-end electronics, as a function of the main parameters of the detector and the preamplifier, taking into account the parasitic inductance. The model is useful to evaluate the influence of each parameter of the system on the slope of its response and to guide the designer in the definition of the architecture and the specifications for the front-end electronics. The results provided by the model have been successfully compared with experimental measurements from a front-end circuit with variable configuration based on a bipolar junction transistor (BJT), coupled to a 3 × 3 mm2 SiPM stimulated by a fast-pulsed laser source.

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The phototransduction machinery in the rod outer segment has a strong efficacy gradient

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1423162112 ◽

2015 ◽

Vol 112 (20) ◽

pp. E2715-E2724 ◽

Cited By ~ 14

Author(s):

Monica Mazzolini ◽

Giuseppe Facchetti ◽

Laura Andolfi ◽

Remo Proietti Zaccaria ◽

Salvatore Tuccio ◽

...

Keyword(s):

Light Intensity ◽

Optical Fibers ◽

Outer Segment ◽

Single Photon ◽

Electrical Signal ◽

Diffuse Light ◽

Rod Photoreceptors ◽

Rod Outer Segment

Rod photoreceptors consist of an outer segment (OS) and an inner segment. Inside the OS a biochemical machinery transforms the rhodopsin photoisomerization into electrical signal. This machinery has been treated as and is thought to be homogenous with marginal inhomogeneities. To verify this assumption, we developed a methodology based on special tapered optical fibers (TOFs) to deliver highly localized light stimulations. By using these TOFs, specific regions of the rod OS could be stimulated with spots of light highly confined in space. As the TOF is moved from the OS base toward its tip, the amplitude of saturating and single photon responses decreases, demonstrating that the efficacy of the transduction machinery is not uniform and is 5–10 times higher at the base than at the tip. This gradient of efficacy of the transduction machinery is attributed to a progressive depletion of the phosphodiesterase along the rod OS. Moreover we demonstrate that, using restricted spots of light, the duration of the photoresponse along the OS does not increase linearly with the light intensity as with diffuse light.

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Method For Measuring Sub-Micron Facula At Single-Photon Level With Silicon Photomultiplier

10.21203/rs.3.rs-1050434/v1 ◽

2021 ◽

Author(s):

Yaxian Yang ◽

Guoqing Zhang ◽

Chen Zhang ◽

Xinyue Cao ◽

Lina Liu ◽

...

Keyword(s):

Single Photon ◽

Dimensional Space ◽

Avalanche Photodiode ◽

Objective Lens ◽

Silicon Photomultiplier ◽

Silicon Photomultipliers ◽

Positioning Stage ◽

Weak Light ◽

Single Photon Response ◽

Nominal Resolution

Abstract Sub-micron faculae (light spots) at the single-photon level have important applications in many fields. This report demonstrates a method for measuring facula size at the sub-micron single-photon level indirectly. The developed method utilizes Silicon Photomultipliers (SiPMs) as the single-photon response detectors, combined with a nano-positioning stage. The approach involves one- or two-dimensional space scanning and a deconvolution operation, which enable evaluations of the size and spatial distribution of focused facula in a single-photon-level pulsed laser. The results indicate that the average full width at half maximum of the faculae is about 0.66 µm, which is close to the nominal resolution of the objective lens of the microscope (0.42 µm). The proposed method has two key advantages: (1) it can measure sub-micron facula at the single-photon level, and (2) the sub-micron facula can easily be aligned with the detector because the array area of the avalanche photodiode cells in SiPM is usually larger than one square millimeter, and there is no need to put an optical slit, knife edge, or pinhole in front of the detector. The method described herein is applicable in weak light facula detection related fields.

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Behavioural and physiological limits to vision in mammals

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2016.0072 ◽

2017 ◽

Vol 372 (1717) ◽

pp. 20160072 ◽

Cited By ~ 14

Author(s):

Greg D. Field ◽

Alapakkam P. Sampath

Keyword(s):

Single Photon ◽

Signal Transmission ◽

High Sensitivity ◽

Human Vision ◽

Past Century ◽

Single Photons ◽

Rod Photoreceptors ◽

Physiological Limits ◽

Visual Threshold ◽

Behavioural Experiments

Human vision is exquisitely sensitive—a dark-adapted observer is capable of reliably detecting the absorption of a few quanta of light. Such sensitivity requires that the sensory receptors of the retina, rod photoreceptors, generate a reliable signal when single photons are absorbed. In addition, the retina must be able to extract this information and relay it to higher visual centres under conditions where very few rods signal single-photon responses while the majority generate only noise. Critical to signal transmission are mechanistic optimizations within rods and their dedicated retinal circuits that enhance the discriminability of single-photon responses by mitigating photoreceptor and synaptic noise. We describe behavioural experiments over the past century that have led to the appreciation of high sensitivity near absolute visual threshold. We further consider mechanisms within rod photoreceptors and dedicated rod circuits that act to extract single-photon responses from cellular noise. We highlight how these studies have shaped our understanding of brain function and point out several unresolved questions in the processing of light near the visual threshold. This article is part of the themed issue ‘Vision in dim light’.

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