Twelve patients with Stargardt's dystrophy were each found to have a prolongation in rod dark adaptation. All had a normal rate of recovery during the early portion of rod dark adaptation but a selective prolongation of the later segment of rod recovery. This observation was apparent in patients with limited ...

We studied rod function in the chicken by recording corneal electroretinograms (ERGs). The following experiments were performed to demonstrate rod function during daytime: (1) determining the dark-adaptation function; (2) measuring the spectral sensitivity by a a-b-wave amplitude criterion in response to monochromatic flickering light of different frequencies ranging from 6.5-40.8 ...

This study examined the ability to perceive surface separation on the basis of mechanical stimulation resulting from striking the surfaces' interiors with a hand-held rod. The variables manipulated were aperture size, angular displacement theta, distance b of the point of contact with the surfaces from the axis of rotation, hand-rod ...

The pearl mutant mouse is hypopigmented and exhibits a significantly elevated dark-adapted (DA) threshold in comparison to the congenic wild-type mouse. The primary cause of the elevated DA threshold is not known. The subcellular immunolocalization of arrestin/S-antigen reflects the state of adaptation of rod photoreceptors. In this study, quantitative immunoelectron ...

The dark adaptation behaviors of rod-driven and cone-driven horizontal cells were examined by analyzing their light responses recorded intracellularly in the intact, immobilized carp, and compared with that of the electroretinographic b-wave recorded simultaneously. Like the b-wave, the light responsiveness of rod horizontal cells increased gradually with time in the ...

1. The effects of steady light on the sensitivity and kinetics of the photocurrent response were studied in the rod photoreceptors of the guinea-pig, using suction pipette recordings of circulating current. 2. The sensitivity of the flash response decreased with increasing background intensity according to Weber's law. Ultimately for the ...

Various concentrations of three dopamine antagonists (fluphenazine, haloperidol and sulpiride) with different affinities to the receptor subtypes were applied in order to test their effect on responses from outer (isolated PIII-component of the ERG), middle (b-wave) and inner (optic nerve response, ONR) retinal layers, recorded from dark-adapted, isolated, arterially-perfused cat ...

We have examined microtubules and microtubule-like elements within the toad rod photoreceptor outer segment in order to define regional specializations of the photoreceptor cytoskeleton. "Ciliary" microtubules were localized within the rod outer segment (ROS) by using thin section electron microscopy, immunofluorescence, and rapid-freeze deep-etch microscopy. All three methods showed that ...

The responses of rabbit rods to light were studied by drawing a single rod outer segment projecting from a small piece of retina into a glass pipette to record membrane current. The bath solution around the cells was maintained at near 40 degrees C. Light flashes evoked transient outward currents ...

Neural adaptation to light stimulation in the dark-adapted retina can be demonstrated by double-flash electroretinography. The first flash is a conditioning flash, the second flash is the test flash. Interstimulus intervals are in the range of 0.2 to 30 seconds. Suppression of the response to the test flash is assumed ...

The process of light adaptation in cat horizontal cells was studied by means of intracellular recordings in the optically intact, in situ eye. Response vs intensity profiles were measured using increment- as well as decrement-flashes of "white light" on steady backgrounds. The effects of background illumination in the mesopic and ...

Changes in light sensitivity, response time-course and electrical coupling of rod driven horizontal cells (RHC) were examined in the dark and light adapted states by intracellular recording. Comparative analyses were made of two fishes from different photic environments. RHC of Cyprinus carpio and external horizontal cells (EHC) of Scyliorhinus canicula ...

1. The influences of short-term visual adaptation of either rods or cones upon cone-mediated grating visibility were compared with their influences upon detection threshold in both the fovea and parafoveal retina. Short-term visual adaptation was induced by 20 deg diameter adapting fields (AFs) generally of 500 ms duration. The AF ...

The cytoplasmic activity of the glutamate synthesizing enzyme aspartate aminotransferase (c-AAT) has been investigated on the ultrastructure level in rod spherules of light and dark adapted rat retinae using cytochemistry. Although most rod terminals react negatively, in a subpopulation of rods a weak activity, which is observed in light adapted ...

A 15-year-old girl complained of color vision difficulties and was found to have an acquired color vision defect with no other abnormalities in the eyes. After 9 years, in addition to the color vision defect, there was gradual loss of visual acuity in both eyes, small central scotomas in the ...

Recent experiments indicate that the dark-adapted vertebrate visual system can count photons with a reliability limited by dark noise in the rod photoreceptors themselves. This suggests that subsequent layers of the retina, responsible for signal processing, add little if any excess noise and extract all the available information. Given the ...

Detection threshold for the rod system was measured psychophysically in adult goldfish before and after exposure to constant illumination of 340 lux (91 microW/cm2) for 7 days. As shown in the previous paper, rod outer segment (ROS) length increases an average of 60% under these conditions. The present work shows ...

In this paper I address some theoretical issues concerning the additivity laws of Grassmann as they might apply to color matches in mesopic vision (in which light intensities are such that both rods and cones are active). It is first shown that rods and cones have linearly independent spectral responses, ...

Magnitude estimates of brightness were obtained for small (5-deg diameter) and large (15 deg X 20 deg) targets viewed through yellow-tinted lenses (ytl's) and luminance-matched neutral lenses. The results indicate that brightness perception with ytl's is up to 40% greater than that with neutral lenses when the spatial extent of ...

Photoactivation of rhodopsin initiates both excitation and adaptation in vertebrate rod photoreceptors. Bleaching of rhodopsin to free opsin and all-trans-retinal in isolated rods produces a stable desensitization (bleaching adaptation) that is much larger than expected from pigment depletion alone. In our experiments, a 93% bleach produced a 500-fold increase in ...

1. The dark current and responses to dim flashes were recorded with the suction pipette technique from single rods in pieces of bull-frog retina taken from either the dorsal porphyropsin or the ventral rhodopsin field. 2. The composition of visual pigment in the rods was determined by microspectrophotometry. Rods from ...

1. The influence of rod adaptation on cone-mediated intracellular responses of distal retinal neurons was examined in the larval tiger salamander. Rods were selectively stimulated by the use of 450-520 nm adapting stimuli too dim to appreciably influence cones. Cones were primarily stimulated with the use of deep-red stimuli (maximally ...

Several features of the evolution of eyes and photoreceptors are examined in an effort to explore the relative roles of adaptation and historical and developmental constraints. Optical design shows clear evidence of adaptation, which in some respects approaches optima predictable from physics. The primate fovea, on the other hand, illustrates ...

The presence of rod and cone photoreceptors has traditionally been linked to well-defined classes of visual capacity by the generalization known as duplicity theory. This paper summarizes results obtained from studies of vision and the visual system in ground squirrels (Spermophilus sp.) that reveal instances where structure/function linkages depart from ...

Redistributions of monkey cones and rods during the first year after birth include a fivefold increase in peak foveal cone density from 43,000 to 210,000 cones/mm2, a decrease in the diameter of the rod-sparse area, and a two- to threefold decrease in peripheral photoreceptor density. Two weeks before birth, higher ...

Synaptic inputs from rods and cones to horizontal cells (HCs) were studied in the flatmounted isolated retinas of the tiger salamander. Voltage-intensity relations, spectral sensitivities and response waveforms of the rod, the cone, and the HC under dark- and light-adapted conditions were examined. HCs receive mixed inputs from rods and ...

Extracellular ganglion cell responses were recorded to investigate mechanisms of light adaptation. Monochromatic test spots (575 nm) were projected onto the receptive field center of off-center cells and superimposed on a steady blue-green Ganzfeld background (Schott Filter BG 28), the strength of which was increased in steps of 0.5 log ...

Experiments were performed on rod photoreceptors isolated from the eye of the larval tiger salamander to determine if the same or different mechanisms underlie the desensitization produced by dim background light (background adaptation) and that which persists in the steady state in darkness after a significant fraction of the photopigment ...

Video-enhanced differential interference contrast optics was used to determine the number and distribution of photoreceptors across the entire retinal surface of 9 eyes obtained from 7 adult rhesus monkeys. We found that the retina of this primate contains an average of 3,100,000 cones (+/- 130,000) and 61,000,000 rods (+/- 7,500,000). ...

The mechanisms by which sulfhydryl (SH-) binding reagents modulate the light-sensitive conductance of retinal rods were investigated by current recording from single rods, by patch clamp recording from the plasma membrane of the rod outer segment (ROS), and by biochemical study of their effects on the light-induced hydrolysis of cyclic ...

Bleaching of rhodopsin markedly desensitizes the vertebrate visual system during a subsequent period of dark adaptation. Previous studies have indicated an origin of bleaching desensitization in the visual pigment itself, but have not identified the mechanism of action. A candidate for the site at which densensitization is initially expressed is ...

Cone photoreceptors are less sensitive to light and the duration of their photoresponse is shorter than that of rods. In salamander rods and cones, we identified 3 components in membrane currents activated by bright flashes of light: an early receptor current (ERC) resulting from charge displacement within visual pigments, a ...

This study assessed the relative ability of 7 field-independent and 8 field-dependent persons to detect changes in rod and frame positions. Each subject received 90 discrimination trials. Each trial consisted of the standard stimulus (both rod and frame tilted 15 degrees to the subject's left) followed by a comparison stimulus ...

We have measured the spatial density of cones and rods in eight whole-mounted human retinas, obtained from seven individuals between 27 and 44 years of age, and constructed maps of photoreceptor density and between-individual variability. The average human retina contains 4.6 million cones (4.08-5.29 million). Peak foveal cone density averages ...

It has been known for over a century that rod photoreceptors in the living retina contract and swell in response to light. Although it is still not known whether this structural light-response is of any functional significance, it has recently been possible to correlate the underlying molecular processes with the ...

Rod saturation on flashed and steady red backgrounds was investigated in normals and three achromats, two of whom were found to have some residual cone function. LWS cones selectively reduce the background level at which rod saturation occurs and elevate rod thresholds at flashed background levels well below saturation. Both ...

We present new psychophysical estimates of the size of the rod pool for bleaching adaptation in the human retina. We estimate that at 5 deg nasal eccentricity in the human retina the size of the adaptation pool for rods is between 5 and 7.5 min arc. This estimate is compatible ...

The electroretinogram and responses of intermediate horizontal cells (IHCs) were recorded simultaneously and studied under dark-adapted conditions in intact crucian carp, with the hope of providing an answer to the controversy whether the scotopic b-wave contains contribution from both rods and cones. Our observations indicate that the dark-adapted b-wave follows ...

In the duplex (rod/cone) retinae of most vertebrates, electrical responses associated with nocturnal vision can be recorded in relative isolation only over a limited intensity range before there is encroachment by signals from the cone system; e.g., at mesopic levels of illumination, the rods begin to saturate, and the cone ...

Rod-cone interactions in flicker and hue detection were compared to examine the hypothesis that they are mediated by mechanisms with different spatial properties. Flicker and hue thresholds for a 1 deg test stimulus (TS) were measured as a function of background luminance and diameter. Flicker thresholds were reduced from their ...

The morphology of the retinal photoreceptors of the butterfly fish Pantodon buchholzi has been studied by electron microscopy in both light- and dark-adaptation. The photoreceptors in this species are readily divisible into rods and cones based on morphological criteria. No double or twin cones are present. The rod photoreceptors show ...

Previous studies reported that the oscillatory potentials (OPs) evoked to the first flash of a series were always smaller than those produced by the later flashes. This conditioning flash effect (CFE) was suggested to arise from rod inhibition of cone-mediated OPs. We investigated this CFE with the use of two ...

New visual pigments were formed with 4-hydroxy retinals in isolated vertebrate rod photoreceptors by exposing bleached rods from the tiger salamander, Ambystoma tigrinum, to lipid vesicles containing the analogues. Formation of physiologically active pigment was demonstrated by the restoration of sensitivity and by a shift of approximately 50 nm in ...

Following substantial bleaches, the specific form and hue thresholds were measured during dark adaptation with a test stimulus of 1 x 2 degrees at 40 degrees extrafoveally. The wavelength of the test field was varied between runs. The results show that both thresholds started to rise at about the cone-rod ...

After visual-pigment bleaching, single isolated rod photoreceptors of Ambystoma tigrinum recover their sensitivity to light when supplied with 11-cis-retinal from liposomes or with 11-cis-retinal bound to interphotoreceptor retinoid-binding protein. Bleached rods do not recover sensitivity, or do so only very slowly, after exposure to 11-cis-retinol. The latter retinoid is "toxic" ...

1. The kinetics of photoresponses to flashes and steps of light of rods, from the retina of the newt Triturus cristatus, were analysed by recording the membrane current with a suction electrode. 2. In dark-adapted conditions the relation between the normalized amplitude of the photoresponse at a fixed time 1 ...

In spite of the crucial role retinal photoreceptors play in mapping optical images into a pattern of neural excitation, there are no complete studies of photoreceptor topography in any primate retina. We have measured the spatial density and inner segment areas of cones and rods across the whole mounted retinas ...

Light-evoked membrane currents were recorded with suction electrodes from the outer segments of individual photoreceptors enzymatically dissociated from the skate retina. The intensity-response relation of dark-adapted cells closely followed a Michaelis function for which a half-saturating response was elicited by a flash intensity that produced about 36 photoisomerizations. Dim-light responses, ...

We test the hypothesis that the diameters of foveal and near-foveal rods and cones for one well-studied human photoreceptor mosaic and one well-studied monkey photoreceptor mosaic (Macaca fascicularis) are scaled relative to focal length. We conclude that this hypothesis is not supported. Rather than being scaled proportionally, the sizes of ...

It has long been an open question whether individual rod receptors in the mammalian retina show any light adaptation. The prevailing evidence so far has suggested that these cells, unlike those in lower vertebrates, adapt little if at all. The experiments on cat rods reported here, however, indicate that this ...