The early receptor potential (ERP)

Müller, Winfried; Töpke, H.

doi:10.1007/bf00144737

Cited by 4 publications

(7 citation statements)

References 52 publications

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“…A strong ERP signal has only been observed in patch clamp measurements of cones, whose disks are continuous with the outer segment membrane, and hence the transmembrane potential is accessible to the probe patching the cilium [1], [2]. In rod photoreceptors, however, most of the disk membranes are pinched off and stacked within the outer segment membrane.…”

Section: Discussionmentioning

confidence: 99%

“…The ERP is attributed to the charge transfer across the cell membrane associated with the conformational change of the opsin (photoisomerization) embedded in that membrane. This ERP signal is distinct from the late receptor potential (LRP), which corresponds to changes in the cell potential associated with closing of the ion channels in outer segments following the phototransduction cascade [1], [2]. As illustrated in Figure 1, the change from 11 cis-to all-trans conformation of the opsin during isomerization effectively results in the movement of a single charge by approximately 12% across the cell membrane.…”

Section: Early Receptor Potentialmentioning

confidence: 99%

“…We assume that the observed ms-fast decrease of the OPL through the photoreceptor outer segments is related to the early receptor potential (ERP)-a ms-fast electrical signal following a bright stimulus, which can be recorded in cone photoceptors via patch clamp [1], [2]. The ERP is attributed to the charge transfer across the cell membrane associated with the conformational change of the opsin (photoisomerization) embedded in that membrane.…”

Section: Early Receptor Potentialmentioning

confidence: 99%

“…Understanding the resulting electrical and biochemical activity throughout this response is very important for comprehending visual function in general, and diagnosis of its pathology in particular. Until now, electrical signals in photoreceptors and other retinal cells have been measured using intracellular or extracellular electrodes [1]- [3]. Recently, phase-resolved imaging of photoreceptors demonstrated significant changes in the optical path length (OPL) in response to flash stimuli [4]- [6].…”

Section: Introductionmentioning

confidence: 99%

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On mechanisms of light-induced deformations in photoreceptors

Boyle

Chen

Ling

et al. 2020

Preprint

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Photoreceptors in the retina convert light into electrical signals through a phototransduction cycle that consists of multiple electrical and biochemical events. Phase-resolved optical coherence tomography (pOCT) measurements of the optical path length (OPL) change in the cone photoreceptor outer segments after a light stimulus (optoretinogram) reveal a fast, ms-scale contraction by tens of nm, followed by a slow (hundreds of ms) elongation reaching hundreds of nm. Ultrafast measurements with a line-scan pOCT system show that the contractile response amplitude increases logarithmically with the number of incident photons, and its peak shifts earlier at higher stimulus intensities.We present a model that accounts for these features of the contractile response. Conformational changes in opsins after photoisomerization result in the fractional shift of charge across the disk membrane, leading to a transmembrane voltage change, known as the early receptor potential (ERP). Lateral repulsion of the ions on both sides of the membrane affects its surface tension and leads to its lateral expansion. Since the volume of the disks does not change much on a ms time scale, their lateral expansion leads to an axial contraction of the outer segment. With increasing stimulus intensity and resulting tension, the area expansion coefficient of the disk membrane also increases as thermally-induced fluctuations are pulled flat, resisting further expansion. This results in a logarithmic saturation of the deformation and a peak shift to earlier with brighter stimuli. Slow expansion of the photoreceptors is explained by the influx of water due to osmotic changes during phototransduction. Both effects closely match measurements in healthy human volunteers.

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Section: Discussionmentioning

confidence: 99%

Section: Early Receptor Potentialmentioning

confidence: 99%

Section: Early Receptor Potentialmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On mechanisms of light-induced deformations in photoreceptors

Boyle

Chen

Ling

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Understanding the resulting electrical and biochemical activity throughout this response is very important for comprehending visual function in general and for diagnosis of its pathology in particular. Until now, electrical signals in photoreceptors and other retinal cells have been measured using intracellular or extracellular electrodes (1)(2)(3). Recently, phase-resolved imaging of photoreceptors demonstrated significant changes in the optical path length (OPL) in response to flash stimuli (4)(5)(6).…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Light-Induced Deformations in Photoreceptors

Boyle

Chen

Ling

et al. 2020

Biophysical Journal

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Biological cells deform on a nanometer scale when their transmembrane voltage changes, an effect that has been visualized during the action potential using quantitative phase imaging. Similar changes in the optical path length have been observed in photoreceptor outer segments after a flash stimulus via phase-resolved optical coherence tomography. These optoretinograms reveal a fast, millisecond-scale contraction of the outer segments by tens of nanometers, followed by a slow (hundreds of milliseconds) elongation reaching hundreds of nanometers. Ultrafast measurements of the contractile response using line-field phase-resolved optical coherence tomography show a logarithmic increase in amplitude and a decreasing time to peak with increasing stimulus intensity. We present a model that relates the early receptor potential to these deformations based on the voltage-dependent membrane tension-the mechanism observed earlier in neurons and other electrogenic cells. The early receptor potential is caused by conformational changes in opsins after photoisomerization, resulting in the fractional shift of the charge across the disk membrane. Lateral repulsion of the ions on both sides of the membrane affects its surface tension and leads to its lateral expansion. Because the volume of the disks does not change on a millisecond timescale, their lateral expansion leads to an axial contraction of the outer segment. With increasing stimulus intensity and the resulting tension, the area expansion coefficient of the disk membrane also increases as thermally induced fluctuations are pulled flat, resisting further expansion. This leads to the logarithmic saturation observed in measurements as well as the peak shift in time. This imaging technique therefore relates the structural changes in the photoreceptor to the underlying neurological function of transducing light into electrical signals. Such label-free optical monitoring of neural activity using fast interferometry may be applicable not only to optoretinography but also to neuroscience in general.

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Objective Assessment of Retinal Function

Sandberg¹

2008

Albert &Amp;amp;amp Jakobiec's Principles &Amp;amp;amp Practice of Ophthalmology

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The early receptor potential (ERP)

Cited by 4 publications

References 52 publications

On mechanisms of light-induced deformations in photoreceptors

On mechanisms of light-induced deformations in photoreceptors

Mechanisms of Light-Induced Deformations in Photoreceptors

Objective Assessment of Retinal Function

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