Absorption spectra and linear dichroism of some amphibian photoreceptors.

Hárosi, Ferenc I.

doi:10.1085/jgp.66.3.357

Cited by 245 publications

(258 citation statements)

References 29 publications

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“…The estimated collecting area obtained from 15 rods was 17 Ϯ 2 m 2 (mean Ϯ SEM), with a range across cells of 10 -23 m 2 . These values are similar to estimates based on outer segment volume and rhodopsin concentration (Harosi, 1975). The collecting area estimated from each rod was used to convert photon density to Rh*/rod.…”

Section: Light Calibration and Comparison Of Different Preparationsmentioning

confidence: 74%

Detection Sensitivity and Temporal Resolution of Visual Signals near Absolute Threshold in the Salamander Retina

Chichilnisky¹,

Rieke²

2005

J. Neurosci.

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Several studies have suggested that the visual system can detect dim lights with a fidelity limited only by Poisson fluctuations in photon absorption and spontaneous activation of rhodopsin. If correct, this implies that neural processing of responses produced by rod photoreceptors is efficient and effectively noiseless. However, experimental uncertainty makes this conclusion tenuous. Furthermore, previous work provided no information about how accurately stimulus timing is represented. Here, the detection sensitivity and temporal resolution of salamander rods and retinal ganglion cells (RGCs) are compared in nearly matched experimental conditions by using recorded responses to identify the time of a flash. At detection threshold, RGCs could reliably signal the absorption of 20 -50 photons, but the rods within the RGC receptive field could signal stimuli 3-10 times weaker. For flash strengths 10 times higher than detection threshold, some RGCs could distinguish stimulus timing with a resolution finer than 100 msec, within a factor of 2 of the rod limit. The relationship between RGC and rod sensitivity could not be explained by added noise in the retinal circuitry but could be explained by a threshold acting after pooling of rod signals. Simulations of rod signals indicated that continuous noise, rather than spontaneous activation of rhodopsin or fluctuations in the single-photon response, limited temporal resolution. Thus, detection of dim lights was limited by retinal processing, but, at higher light levels, synaptic transmission, cellular integration of synaptic inputs, and spike generation in RGCs faithfully conveyed information about the time of photon absorption.

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Section: Light Calibration and Comparison Of Different Preparationsmentioning

confidence: 74%

Detection Sensitivity and Temporal Resolution of Visual Signals near Absolute Threshold in the Salamander Retina

Chichilnisky¹,

Rieke²

2005

J. Neurosci.

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“…To simplify the calculation, all light sources were treated as monochromatic light, with all the power at the spectral peak. To estimate the bleaching effect of imaging lights, we assumed a total 7.4 log 10 pigments in a M cone (Fu 2011), estimated from cone outer segment volume of 14 m 3 (Carter-Dawson and LaVail 1979) and a pigment concentration of ϳ3 mM (Harosi 1975). Psychophysics Toolbox extensions (Brainard 1997;Pelli 1997) were used for calculating isomerization rates.…”

Section: Methodsmentioning

confidence: 99%

Imaging light responses of retinal ganglion cells in the living mouse eye

Yin

Geng

Osakada

et al. 2013

Journal of Neurophysiology

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This study reports development of a novel method for high-resolution in vivo imaging of the function of individual mouse retinal ganglion cells (RGCs) that overcomes many limitations of available methods for recording RGC physiology. The technique combines insertion of a genetically encoded calcium indicator into RGCs with imaging of calcium responses over many days with FACILE (functional adaptive optics cellular imaging in the living eye). FACILE extends the most common method for RGC physiology, in vitro physiology, by allowing repeated imaging of the function of each cell over many sessions and by avoiding damage to the retina during removal from the eye. This makes it possible to track changes in the response of individual cells during morphological development or degeneration. FACILE also overcomes limitations of existing in vivo imaging methods, providing fine spatial and temporal detail, structure-function comparison, and simultaneous analysis of multiple cells.retinal ganglion cells; in vivo adaptive optics imaging; calcium imaging AVAILABLE METHODS FOR EXAMINING the physiology of retinal ganglion cells (RGCs) have marked limitations, which are resolved by the novel in vivo imaging method described here.

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“…To provide access to the ligand binding pocket ofopsin, the native chromophore (13) 11-cis-3,4-dehydroretinal (Fig. 1, structure 2) was removed by bleaching.…”

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confidence: 99%

Relief of opsin desensitization and prolonged excitation of rod photoreceptors by 9-desmethylretinal.

Corson

Cornwall

MacNichol

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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The 9-methyl group of 11-s-retinal plays a crucial role in photoexcitation of the visual pigment rhodopsin. A hydrogen-substituted analogue, 11-cis-9-desmethylretlnal, combines with opsin to form a pigment that produces abnormal photoproducts and diinished activation of the GTP-binding protein transducin in vitro. We have measured the formation of this analogue pigment in bleached salamander rods and determined the size and shape of its quantal response. In addition, we have characterized the influence of opsin and newly formed analogue pigment on the quantal response to native porphyropsin. We find that, as 11-cis-9-desmethylretinal combines with opsin in bleached rods, the amplitude of the quantal response from residual native pigment is elevated by 74.5-fold to 0.15 ± 0.09 pA, a value close to the amplitude of the quantal response before bleach (0.31 ± 0.10 pA). When activated by light, the new analogue pigment produces a quantal response that is ==30-fold smaller and decays ""5 times more slowly than that ofnative pigment in unbleached cells. We conclude that the 9-methyl group of retinal is not critical for conversion of opsin to its nondesensitizing state but that it is critical for the normal processes of activation and deactivation of metarhodopsin that give rise to the quantal response.Photoisomerization of li-cis-retinal (Fig. 1, structure 1) initiates an intramolecular rearrangement of rhodopsin that results in a catalytically active state of rhodopsin, R * (1-5). Deactivation of R* requires phosphorylation by rhodopsin kinase (6, 7) and the subsequent binding of arrestin (3,(7)(8)(9). In isolated photoreceptors, pigment activation and deactivation produce a discrete electrical response with a characteristic amplitude and time course (10,11). In an examination of the steric interactions between the apoprotein opsin and its chromophore, Ganter et al. (12) reported that 11-cis-9-desmethylretinal ( Fig. 1, structure 3) produced abnormal photoproducts and transducin activation that was 8% of the rhodopsin control. Here we examine the influence of the 9-methyl group of retinal on the amplitude and shape of the quantal response in isolated rods.To provide access to the ligand binding pocket ofopsin, the native chromophore (13) 11-cis-3,4-dehydroretinal (Fig. 1, structure 2) was removed by bleaching. Bleaching reduces the sensitivity of a cell by depleting the supply of native pigment and by reducing the amplitude of the quantal response from the residual pigment (14)(15)(16)(17). In the absence of li-cis-retinal, this desensitization persists indefinitely (15,18) and is unresponsive to the addition of all-trans-retinal (15,19) or its removal from opsin by hydroxylamine (20,21). We refer to the persistent component of desensitization that results from response attenuation and does not require the presence of a retinal-containing photoproduct as opsin desensitization. Taken together with the loss of sensitivity resulting from pigment depletion, the total loss of sensitivity is commonly referred to as ...

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Absorption spectra and linear dichroism of some amphibian photoreceptors.

Cited by 245 publications

References 29 publications

Detection Sensitivity and Temporal Resolution of Visual Signals near Absolute Threshold in the Salamander Retina

Detection Sensitivity and Temporal Resolution of Visual Signals near Absolute Threshold in the Salamander Retina

Imaging light responses of retinal ganglion cells in the living mouse eye

Relief of opsin desensitization and prolonged excitation of rod photoreceptors by 9-desmethylretinal.

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