Spectral Sensitivity Curves Research Articles

Optoelectronic properties of CdO/Si photodetectors

CdO/Si heterojunctions were fabricated by depositing CdO polycrystalline thin films on p-type single crystalline silicon wafers by CBD. The current–voltage characteristics under dark and illumination of CdO/Si devices resemble those of a light sensitive diode. From the CdO/Si diode spectral sensitivity curves (A/W), it has been implied that CdO films allow a high sensitivity response in the visible and the near infrared regions.

Cone inputs to murine retinal ganglion cells

Responses of single retinal ganglion cells in different areas of mouse retina were studied to determine their cone inputs, using spectral sensitivity functions and chromatic adaptation. Spectral sensitivity curves were based on threshold response criteria to full field stimulation. The retina of the mouse was viewed through a dilated pupil with a surgical microscope. Ganglion cells were classified into three groups: one receiving inputs from short wave sensitive cones, a second receiving inputs from only middle wavelength sensitive cones and a third receiving inputs from both of these types of cones. The ventral retina, contained a large fraction of the first group of ganglion cells. The dorsal retina and the border between these two areas contained relatively more of the latter two groups. A small fraction of cells were found which displayed antagonistic-like interactions between photoreceptor systems. The results demonstrate that single ganglion cells in mouse retina can select responses from only one of the two cone mechanisms present in this retina, even in areas containing both types of cones.

Spectral correspondence between visual spectral sensitivity and bioluminescence emission spectra in the click beetle Pyrophorus punctatissimus (Coleoptera: Elateridae)

The presence of two spectral mechanisms, near-ultraviolet and green ( λ max=545 nm), is strongly suggested by electroretinographic visual spectral sensitivity curves obtained under dark and red chromatic adaptation conditions in the compound eyes of the click beetle Pyrophorus punctatissimus. The bioluminescence emission of the dorsal prothoracic lanterns is deep green ( λ max=543 nm) and that of the ventral abdominal lantern is lime green ( λ max=556 nm) in colour in P. punctatissimus. A broad green visual receptor would detect both deep green and lime green bioluminescent optical signals.

Relative number of long- and middle-wavelength-sensitive cones in the human fovea.

Flicker photometric measurements yield spectral sensitivity curves that are well fitted by sums of the spectral sensitivity curves of long-wavelength-sensitive (L) cones and middle-wavelength-sensitive (M) cones if the L cones are given twice the weight of the M cones. This result has been interpreted as implying that L cones are more numerous than M cones but is also consistent with a different numerical ratio, say, 1:1, and with the assignment of greater weight to the L cone input than to the M cone input by the mechanism subserving flicker photometry. Measurements of temporal sensitivity are presented for lights that modulate the inputs of either only the L cones or only the M cones. Sensitivity to modulation of the L cones is approximately twice that of modulation of the M cones at approximately 30 Hz, but that advantage disappears at approximately 2 Hz. Thus flicker sensitivity is equivocal with regard to cone numerosity. Electrophysiological, anatomical, and psychophysical evidence is reviewed, with particular weight placed on the statistics of color appearance of small, brief, monochromatic lights and on increment thresholds measured on the same observers. It is concluded that, in the central fovea, the ratio of L:M cone numbers is close to unity and may not be so variable as is usually supposed.

Flicker-photometric electroretinogram estimates of L:M cone photoreceptor ratio in men with photopigment spectra derived from genetics.

Relative proportions of long-wavelength-sensitive (L) to middle-wavelength-sensitive (M) cones were estimated by use of the flicker-photometric electroretinogram (ERG). It has been demonstrated that a major source of error in estimates of cone proportions from spectral luminosity functions is the known variation in the lambda(max) of the photopigments [Vision Res. 38, 1961 (1998)]. To correct for these errors, estimates of cone proportions were derived by use of individualized L-cone spectral sensitivity curves deduced from photopigment gene sequences from each subject. For some individuals this correction made a large difference in the estimated cone proportions compared with the value obtained when a fixed standard L cone was assumed. The largest discrepancy occurred in a man estimated to have 62% L cones (L:M ratio 1.6:1) when a standard L pigment was assumed but a value of 80% L cones (L:M ratio 4:1) when his individualized L-cone spectrum was used. From repeated measurements made with the ERG, it was determined that individual estimates of the relative L-to-M cone contributions, expressed as %L cones, are usually reliable within approximately 2%. The average L:M ratio for 15 male subjects was estimated at 2:1 (67% L cones). Previously, a large range of individual variability was reported for L:M ratios obtained from photometry. An unresolved issue concerns how much of the range might be attributed to error. Here efforts have been taken to markedly reduce measurement error. Nonetheless, a large range of individual differences persists. Estimated L:M ratios for individuals ranged from 0.6:1 to 12:1 (40% L to 92% L).

42] Spectral sensitivities of human cone visual pigments determined in vivo and in vitro

Publisher Summary This chapter summarizes the current status of the spectral sensitivity curves that underlie normal and anomalous human color vision, with an emphasis on in vivo psychophysical measurements in genetically well-characterized subjects and in vitro measurements with recombinant cone pigments. The existence of polymorphisms among normal M and L pigment genes, most especially the A180/S180 polymorphism, means that a single set of cone fundamentals will accurately describe the color vision of only a subset of normal trichromats, and that in the construction of an average set of fundamentals it is important that the weighting of polymorphic types within the test population match that in the general population. Thus, the in vivo determination of the cone fundamentals requires an analysis of the spectral sensitivity curves for subjects whose visual pigment gene sequences reveal which of the various possible pigments they possess. By building on advances in molecular biology and exploiting high-precision in vivo and in vitro techniques, significant progress has been made toward the goal of fully cataloging the rich diversity of cone photopigments that underlie normal and anomalous human color vision.

Spectral Sensitivity of the Hawaiian Saddle Wrasse, Thalassoma duperrey, and Implications for Visually Mediated Behaviour on Coral Reefs

Although tropical coral reefs are one of the most spectrally complex habitats, there is relatively little known about colour vision of reef fish. In this study, we measured the spectral sensitivity of an endemic Hawaiian coral reef fish, Thalassoma duperrey (family Labridae), and assessed the possible role of visual sensitivity in mediating intraspecific communication. Electrophysiological recordings of compound action potentials from retinal ganglion cells were used to generate spectral sensitivity curves for specific wavelengths (380–620 nm). We found at least 2 sensitivity peaks for the on response (λmax=460, 550 nm). The off response lacked a short wavelength mechanism but a medium wavelength mechanism (λmax=545 nm) and a longwave mechanism (λmax=570 nm) were found. To quantify the visual stimulus provided by a conspecific individual, spectral reflectance from the colour pattern of T. duperrey was measured with a spectroradiometer. Luminance and spectral contrast were computed between colour patches of the pattern and between the patches and natural backgrounds (i.e., water and coral). Reflectance from the blue head and contrast from the blue, green and red patches matched the sensitivity maxima of T. duperrey, although this depended on the type of background. Our results indicate that T. duperrey should be able to visually detect the colour pattern of a conspecific fish and that T. duperrey's visual system is designed to enhance target detection in the coral reef habitat with matched and offset cone mechanisms.

The role of the spectral sensitivity curve in the selection of relevant biological dosimeters for solar UV monitoring

To estimate the risk of enhanced UV-B radiation due to stratospheric ozone depletion, phage T7 and uracil thin-layer biological dosimeters have been developed, which weight the UV irradiance according to induced DNA damage. To study the molecular basis of the biological effects observed after UV irradiation, the spectral sensitivity curves of the two dosimeters and induction of the two major DNA photoproducts, cyclobutane pyrimidine dimers (CPDs) and 6–4 photoproducts ((6–4)PDs), in phage T7 have been determined for polychromatic UV sources. CPDs and (6–4)PDs are determined by lesion-specific monoclonal antibodies in an immunodotblot assay. Phage T7 and uracil biological dosimeters together with a Robertson–Berger (RB) meter have been used for monitoring environmental radiation from the polar region to the equator. The biologically effective dose (BED) established with the three different dosimeters increases according to the changes in the solar angle and ozone column, but the degree of the change differs significantly. The results can be explained based on the different spectral sensitivities of the dosimeters. A possible method for determining the trend of the increase in the biological risk due to ozone depletion is suggested.

Wavelength sensitivity of photo-oxidation of polyamide 6

The wavelength sensitivity of polyamide 6 films exposed to filtered xenon arc radiation was studied by the sharp cut filter technique based on the changes in UV absorption. The spectral sensitivity curves and activation spectra were obtained. It was found that the photo-oxidation of PA6 can be caused by light in a wide wavelength range of about 260–480 nm. From the activation spectra it was shown that there exist two distinctly separate spectral regions responsible for causing PA photo-oxidation: wavelengths below 300 nm and in the range of 340–400 nm. The results are discussed from the point of view of the initiation mechanism of PA photo-oxidation..

Cone spectral sensitivity in the harbor seal (Phoca vitulina) and implications for color vision

The retinas of harbor seals (Phoca vitulina) contain two morphologically distinct photoreceptor types: rods and cones. The spectral properties of the cones have not been previously studied. The spectral sensitivities of the cones of harbor seals were measured using a retinal gross potential technique, flicker photometric electroretinography. We found a cone spectral sensitivity curve with a peak at about 510 nm. The shape of the spectral sensitivity curve remained invariant despite large changes in chromatic adaptation, implying that harbor seals have only a single cone photopigment. This means that harbor seals must lack color vision at photopic light levels. Any color discrimination in this species would have to be based on combined input from rods and cones and thus restricted to mesopic light levels. The spectral sensitivity of the cone pigment in the harbor seal is shifted to shorter wavelengths than those of terrestrial carnivores, consistent with adaptation to the aquatic photic environment.

Electroretinographic evaluation of spectral sensitivity in yellow and silver eels (Anguilla anguilla).

Although differences in visual pigments between developmental stages of the European eel are well known, the expected differences in spectral sensitivity have not been demonstrated at the electrophysiological level. In fact, one past electroretinographic study led to the conclusion that in eels there is no change in scotopic sensitivity, with increasing sexual maturity. In the present experiments, electroretinograms (ERGs) were recorded from in situ eyecups of immobilized eels Anguilla anguilla (L.) caught in coastal running waters. It was shown that the ERG b-wave is as good an indicator of spectral sensitivity as the unmasked late receptor potential (LRP) which directly reflects the responsiveness of photoreceptors. Complete spectral-sensitivity curves, based on b-wave thresholds and on thresholds of LRP subsequently isolated by means of sodium iodate, have been obtained in the same eel. Using fitted amplitude-log intensity functions for threshold calculation, and two models for computer-assisted fitting of spectral-sensitivity curves, significant differences in lambda max were found between yellow and silver developmental stages of the eel, identified by ocular index measurements.

視運動反応を利用した魚類の薄明視における分光感度の測定法に関する研究

Optomotor reaction has been studied much to examine the visual function of fish. In this study, the optomotor reaction was utilized in order to measure the spectral sensitivity of fish under scotopic conditions, in which two species of cobaltcap silverside and medaka were investigated. Light of various wavelength was irradiated for the fish which had been fully adapted in the dark and the optomotor reaction of the fish was observed. The optomotor reaction developed more slowly in the darkadapted fish than in fish adapted in the irradiating light. When light of a wavelength giving an absorption maximum for the rod visual pigments of the fish was irradiated, the inhibition of the optomotor reaction was greatest. Thus, the spectral sensitivity curve for the optomotor reaction of dark-adapted fish coincided well with the absorption spectrum of the rod visual pigments in both the species of fish. The usefulness of this behavioral method for ascertaining the spectral sensitivity of fish under scotopic conditions was discussed.

The visual ecology of Puerto Rican anoline lizards: habitat light and spectral sensitivity

The visual ecology of six closely related species of Puerto Rican anoline lizards was investigated and they were found to occupy four distinct habitat types in terms of light conditions: “full shade”, “partial shade”, “no shade”, and “forest canopy.”The habitats differed substantially in total radiance and irradiance as well as in the shape of the irradiance spectrum. The shape of the radiance spectrum was similar in all of the habitats. We used electroretinogram (ERG) flicker photometry to measure spectral sensitivity and found the curves for all six species to be similar. The spectral sensitivity peaked in the range 550–560 nm, which matched the peak in spectral radiance for all of the habitats. The shape of the spectral-sensitivity curve was similar to those of a number of other terrestrial vertebrates. We suggest that the convergence of the shape of the photopic ERG-determined spectral-sensitivity curve in many terrestrial vertebrates may, in part, be due to the fact that the background radiance of many terrestrial habitats is dominated by the reflectance spectrum of green vegetation which peaks at 550 nm.

Thermoluminescence of corundum containing anion defects following ultraviolet laser and x irradiation

The thermoluminescence of single crystals of corundum containing anion defects following x-ray and laser excitation is investigated. Its features in the luminescence bands of F, F+, and Cr3+ centers are studied. Synchronous measurements of the thermoluminescence and thermally stimulated exoelectron emission are performed by the fractional glow technique following x-ray and laser excitation of the samples. It follows from the results obtained that several traps are active in the temperature range of the principal dosimetric peak (400–500 K). The spectral sensitivity curve contains maxima corresponding to absorption bands of F, F+, and Ali+ centers. A possible mechanism for the recombination luminescence of F centers is discussed. It is found that the material exhibits high sensitivity to small doses of ultraviolet laser radiation.

Equating the perceived intensity of coloured lights to hens

1. Previous investigations of the effects of light colour on the productivity or behaviour of chickens have not equated the intensity of the different coloured lights. 2. Ten pullets (Warren Studler 128) were used to determine the perceived intensity of two colours at opposite ends of the visible spectrum (blue, peak wavelength 415 nm and red, peak wavelength 635 nm). 3. Initially half of the birds were trained with food rewards to detect the brighter of two white lights and half the dimmer one. 4. Two discrimination tests then investigated the generalisation of this learnt ability (to distinguish white lights of different intensity) to coloured lights. They were rewarded for distinguishing the brightness of red and blue filtered lights when blue intensity was initially high and gradually reduced, and when red intensity was initially low and gradually increased. The birds identified the lights as being of equal intensity when the blue light was 3.6 times as bright as the red. 5. A second test examined the situation in reverse. A bright red light that was reduced was compared to a dim blue light that was increased in intensity. The birds were again successful and identified the lights as of equal intensity when the blue was 3.1 times as bright as the red. A final test confirmed that there was no difference in the perceived intensity of blue and red lights in the ratios 3.6 or 3.1:1. 6. The difference in perceived red and blue light intensities was less than predicted from the spectral sensitivity curve for chickens. It was expected that the blue light would be perceived as dimmer than the red because the red filter transmitted more light than the blue, and the tungsten filament light illuminating the filter emitted more long than short wavelength light. The observed discrepancy emphasises that perceived intensity is difficult to predict from spectroscopic measurements. 7. The birds then underwent a simple visual test, to discriminate the length of two lines, equally well in red or blue filtered lights that were equiluminescent as determined previously. 8. It is concluded that coloured lights can be equated for intensity by psychophysical testing, and that there was no difference in visual acuity under equiluminescent blue and red filtered lights.

Regional specialization in the eye of the sphingid moth Manduca sexta: blue sensitivity of the ventral retina.

The compound eye of the tobacco hornworm moth Manduca sexta contains green-, blue-, and ultraviolet-sensitive photoreceptors. Electroretinogram spectral-sensitivity measurements were recorded from different regions of the retina in order to broadly map the distribution of the three receptor types. The relative contribution of the three receptors to spectral-sensitivity curves was estimated by fitting theoretical curves based on the absorption spectra of the three rhodopsins. This analysis indicated that the dorsal retina is green and ultraviolet dichromatic, with green-sensitive cells greatly predominating. The ventral retina is trichromatic with a substantial population of blue- and ultraviolet-sensitive receptors. We previously showed that flower visitation for nectar feeding is mediated mainly by blue-sensitive cells. Their localization in the ventral retina seems an appropriate adaptation of the receptor mosaic, since the moths hover above flowers as they feed.

Influence of picrotoxin and strychnine on the spectral sensitivity of the turtle ERG b- and d-waves: II. Light adaptation.

The aim of the present work was to investigate the role of GABA and glycine, the two main inhibitory neurotransmitters in the retina, in the spectral sensitivity coding under conditions of light adaptation. To study this question, spectral sensitivity curves, based on the turtle ERG responses to stimuli of different wavelengths, were constructed. The spectral sensitivity curves. obtained before and during treatment with picrotoxin (PT), a GABAA antagonist, or with strychnine (ST), a glycine antagonist, were compared. Both PT and ST increased the b- and d-wave absolute sensitivity in a wavelength-dependent manner. PT significantly changed the shape of the b- and d-wave spectral sensitivity curves and the latter lost their peaks. It is concluded that, under conditions of light adaptation, GABA and glycine took part in the formation of the b- and d-wave spectral sensitivity curves, that both of them exerted an effect on the gain and that furthermore,GABA had a well pronounced effect on the tuning of the spectral sensitivity curves.

Absolute and Spectral Sensitivities in Dark- and Light-Adapted Pagothenia Borchgrevinki, an Antarctic Nototheniid Fish

Morita, Y., V. B. Meyer-Rochow and K. Uchida. Absolute and spectral sensitivities in dark- and light-adapted Pagothenia borchgrevinki, an Antarctic nototheniid fish. Physiol Behav 61(2) 159–163, 1997.—Functional properties of the retina of Pagothenia borchgrevinki, an Antarctic nototheniid fish that lives beneath the 2.5–3 m thick sea-ice in water of −1.8°C temperature, were analyzed electrophysiologically at Scott Base (77° 50′S; 166° 45′E). The waveform of the ERG was monophasic in the dark-adapted state and showed an off-response of opposite polarity in the light-adapted condition. Responses of the light-adapted retina were smaller than those of the dark-adapted eye, although both photopic and scotopic components were observed. Spectral sensitivity measured by monochromatic photostimulation at 14 different wavelengths across the 400–700-nm range showed a single maximum at 490 nm. The spectral sensitivity curve is consistent with a rhodopsin photopigment. The dark-adapted retina exhibited a photon flux density threshold of approximately 2 × 109 photons cm−2 s−1) when monochromatic flashes of 500 nm wavelength and 250 ms duration were used. When the stimulus consisted of 1 s white light, a minimum energy flux density of approx. 2 × 10−4μW/cm2 was necessary to elicit a detectable response. It was concluded that the visual system of P. borchgrevinki was in tune with the dominant downwelling spectral irradiance and that, due to retinal thermal noise reduction in the cold environment, no great need for particular anatomical adaptations to further enhance sensitivity existed.

Metric analysis of threshold spectral sensitivity in the honeybee.

Behavioral spectral sensitivity curves are frequently used to characterize peripheral stages of visual processing. We test specific hypotheses about the physiology underlying honeybee spectral sensitivity by approximating published sensitivity curves with several metric models. The analysis shows that: (1) models assuming no interactions between different receptor types do not explain the behavioral data. Similarly, neither simple luminance mechanism models (sum of receptor excitations), nor models in which only the most sensitive receptor determines sensitivity fit the data. (2) The minimum number of postreceptoral mechanisms mediating discrimination is two. (3) Both mechanisms are of the chromatic type. Adding an achromatic mechanism decreases the accuracy of approximation.

Electrophysiological measurements of spectral sensitivities: a review.

Spectral sensitivities of visual systems are specified as the reciprocals of the intensities of light (quantum fluxes) needed at each wavelength to elicit the same criterion amplitude of responses. The review primarily considers the methods that have been developed for electrophysiological determinations of criterion amplitudes of slow-wave responses from single retinal cells. Traditional flash methods can require tedious dark adaptations and may yield erroneous spectral sensitivity curves which are not seen in such modifications as ramp methods. Linear response methods involve interferometry, while constant response methods involve manual or automatic adjustments of continuous illumination to keep response amplitudes constant during spectral scans. In DC or AC computerized constant response methods, feedback to determine intensities at each wavelength is derived from the response amplitudes themselves. Although all but traditional flash methods have greater or lesser abilities to provide on-line determinations of spectral sensitivities, computerized constant response methods are the most satisfactory due to flexibility, speed and maintenance of a constant adaptation level.