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Ethambutol affects the spectral and polarisation sensitivity of on-responses in the optic nerve of rainbow trout
Abstract
Juvenile rainbow trout (Oncorhynchus mykiss) were given ethambutol (900 mg kg-1 body mass per day) for 4 weeks to examine its effects on vision. Using multi-unit recording from the optic nerve, spectral sensitivity of the on-responses were significantly affected in two regions, 340-440 nm and 600-660 nm. Off-responses were statistically unaffected. Changes in sensitivity to polarised light were also observed with on-responses to vertically-polarized light decreasing relative to horizontally-polarised light. In contrast, off-responses were less affected. The treatment effects were attributed to changes in the relative contribution of the photoreceptor channels as recorded at the level of the optic nerve.
... Los mecanismos de conos Uv además de estar directamente involucrados en la visión en colores, extendiendo el rango de las longitudes de ondas y la intensidad en la cual la discriminación del color puede ser realizada Hawryshyn & Bolger, 1990;Coughlin & Hawryshyn, 1993;Parkyn & Hawryshyn, 1993;Coughlin & Hawryshyn, 1994aParkyn & Hawryshyn, 1999, contribuyendo a guiar visualmente la búsqueda, detección y captura de presas, especialmente del zooplancton, incrementado su contraste en las aguas superficiales ricas en iluminación ultravioleta (Figura N°12A, 12B, 13A y 13B) (Munz & Beatty, 1965;Beatty, 1966;Munz & McFarland, 1977;Browman, 1985;Bowmaker & Kunz, 1987;Hawryshyn et al., 1989;Douglas & Hawryshyn, 1990;Novales-Flamarique et al., 1992;Beaudet et al., 1993;Novales-Flamarique & Hawryshyn, 1993;Browman et al., 1994;Browman & Hawryshyn, 1994a;Coughlin & Hawryshyn, 1994b;Novales-Flamarique, 2000;Deutschlander et al., 2001;Novales-Flamarique & Browman, 2001), están asociados con la detección y orientación del e-vector 7 de los campos de luz polarizada 8 Kunz & Callaghan, 1989;Hawryshyn & Bolger, 1990;Novales-Flamarique et al., 1992;Parkyn & Hawryshyn, 1993;Browman & Hawryshyn, 1994a;Coughlin & Hawryshyn, 1994aNovales-Flamarique & Hawryshyn, 1996;Parkyn, 1998;Parkyn & Hawryshyn, 1999;7 El vector eléctrico (e-vector): Es el plano en el cual el pez detecta la luz polarizada y la utiliza para funciones de orientación espacial, entre otros (Parkin & Hawryshyn, 1993). Hawryshyn, 2000a,b;Novales-Flamarique, 2000;Parkyn & Hawryshyn, 2000;Novales-Flamarique & Browman, 2001), actuando la división entre los conos dobles (Figura Nº6B), como la base de la detección de la polarización en la trucha arco iris (Novales-Flamarique et al., 1998), en donde el porcentaje de polarización es de 67% en los períodos crepúsculares, a diferencia de las otras horas del día (>40%) (Medición realizada en la zona fótica más cercana a la superficie en aguas meso-eutróficas; i.e., aguas azules verdosas con niveles medios a altos de clorofila) (Novales- Flamarique & Hawryshyn, 1997), exhibiendo los conos Uv de la trucha arco iris, una preferencia máxima a la polarización con el e-vector verticalmente orientado (0° y 180°), mientras que los conos M y L muestran máxima sensibilidad al e-vector horizontalmente orientado (90°) (Figura N°14) Parkyn & Hawryshyn, 1993;Coughlin & Hawryshyn, 1995;Hawryshyn, 2000a;Parkyn & Hawryshyn, 2000), lo que concuerda con los rangos de ingesta de alimento del salmón Atlántico (Figura N°22 y 23; Obs. ...
... Los mecanismos de conos Uv además de estar directamente involucrados en la visión en colores, extendiendo el rango de las longitudes de ondas y la intensidad en la cual la discriminación del color puede ser realizada Hawryshyn & Bolger, 1990;Coughlin & Hawryshyn, 1993;Parkyn & Hawryshyn, 1993;Coughlin & Hawryshyn, 1994aParkyn & Hawryshyn, 1999, contribuyendo a guiar visualmente la búsqueda, detección y captura de presas, especialmente del zooplancton, incrementado su contraste en las aguas superficiales ricas en iluminación ultravioleta (Figura N°12A, 12B, 13A y 13B) (Munz & Beatty, 1965;Beatty, 1966;Munz & McFarland, 1977;Browman, 1985;Bowmaker & Kunz, 1987;Hawryshyn et al., 1989;Douglas & Hawryshyn, 1990;Novales-Flamarique et al., 1992;Beaudet et al., 1993;Novales-Flamarique & Hawryshyn, 1993;Browman et al., 1994;Browman & Hawryshyn, 1994a;Coughlin & Hawryshyn, 1994b;Novales-Flamarique, 2000;Deutschlander et al., 2001;Novales-Flamarique & Browman, 2001), están asociados con la detección y orientación del e-vector 7 de los campos de luz polarizada 8 Kunz & Callaghan, 1989;Hawryshyn & Bolger, 1990;Novales-Flamarique et al., 1992;Parkyn & Hawryshyn, 1993;Browman & Hawryshyn, 1994a;Coughlin & Hawryshyn, 1994aNovales-Flamarique & Hawryshyn, 1996;Parkyn, 1998;Parkyn & Hawryshyn, 1999;7 El vector eléctrico (e-vector): Es el plano en el cual el pez detecta la luz polarizada y la utiliza para funciones de orientación espacial, entre otros (Parkin & Hawryshyn, 1993). Hawryshyn, 2000a,b;Novales-Flamarique, 2000;Parkyn & Hawryshyn, 2000;Novales-Flamarique & Browman, 2001), actuando la división entre los conos dobles (Figura Nº6B), como la base de la detección de la polarización en la trucha arco iris (Novales-Flamarique et al., 1998), en donde el porcentaje de polarización es de 67% en los períodos crepúsculares, a diferencia de las otras horas del día (>40%) (Medición realizada en la zona fótica más cercana a la superficie en aguas meso-eutróficas; i.e., aguas azules verdosas con niveles medios a altos de clorofila) (Novales- Flamarique & Hawryshyn, 1997), exhibiendo los conos Uv de la trucha arco iris, una preferencia máxima a la polarización con el e-vector verticalmente orientado (0° y 180°), mientras que los conos M y L muestran máxima sensibilidad al e-vector horizontalmente orientado (90°) (Figura N°14) Parkyn & Hawryshyn, 1993;Coughlin & Hawryshyn, 1995;Hawryshyn, 2000a;Parkyn & Hawryshyn, 2000), lo que concuerda con los rangos de ingesta de alimento del salmón Atlántico (Figura N°22 y 23; Obs. ...
A review of the implications of the solar light intensity, polarization and ultraviolet radiation in salmonids, related to I.P. 44.321 in Chile. (Spanish version from 2009).
... The fit of the absorptance curves to the resultant spectral sensitivity data was made by vertically adjusting the rainbow trout cone absorptance curves until the best visible fit was obtained (Parkyn and Hawryshyn, 1999). This admittedly simplistic method was employed after attempts had been made to use an additive model which provided an unrealistic and nondescriptive fit of the data (perhaps because of possible inhibitory interactions among cone mechanisms). ...
Spectral and polarisation sensitivity were compared among juvenile (parr) rainbow trout (Oncorhynchus mykiss), steelhead (O. mykiss), cutthroat trout (O. clarki clarki), kokanee (O. nerka) and brook char (Salvelinus fontinalis) using multi-unit recording from the optic nerve. Although reared under the same conditions, differences in photopic spectral sensitivity were evident. Specifically, ON-responses were co-dominated by L- and M-cone mechanisms in all fish except O. nerka, consistent with an M-cone mechanism sensitivity. The sensitivity of OFF-responses was dominated by the M-cone mechanism for all fish, but O. mykiss appeared to show an additional contribution from the L-cone mechanism. Using chromatic adaptation, an independent ultraviolet-sensitive mechanism is described for the first time for the salmonid genus Salvelinus. In addition, this ultraviolet-cone mechanism was present in the members of the genus Oncorhynchus that were examined. Thus, ultraviolet sensitivity appears to be common to the major extant clades of the subfamily Salmoninae. All species showed differential sensitivity to both vertical and horizontal linearly polarised light. This sensitivity differed between ON- and OFF-responses. The ON-responses were maximally sensitive to both vertically and horizontally polarised light, whereas the OFF-responses displayed maximal sensitivity to horizontally polarised light in all species, with reduced sensitivity to vertically polarised light compared with ON-responses. Because of the similarity in the physiological characteristics of polarisation sensitivity among the salmonid species examined, no relationship between the degree of migratory tendency and the ability to detect polarised light could be identified.
Uv cones mechanisms besides directly involved in color vision, extending the range of the wavelengths and intensity in which color discrimination can be done (Hawryshyn et al.,, contributing to visually guide the search, detection and capture of prey, especially zooplankton, increased their contrast in surface waters rich in ultraviolet light Deutschlander et al., 2001; Novales-Flamarique & Browman, 2001), are associated with the detection and e-vector orientation of polarized light fields (Hawryshyn et al.,
We examined orientation responses of juvenile salmonids to a polarized-light stimulus under laboratory conditions. Juvenile rainbow trout, Oncorhynchus mykiss, steelhead (anadromous), O. mykiss, and brook char, Salvelinus fontinalis, were trained using an operant conditioning methodology to orient relative to the axis of a linear-polarized light field. On average, rainbow trout responded correctly relative to the orientation of the light stimulus approximately 70% of the time within five training sessions. The proportion of correct responses increased further under an intermittent reinforcement schedule. We released trained and untrained fish individually in a circular tank and quantified orientation responses using a digital image-tracking system. Experimentally naı̈ve rainbow trout had no directional tendency, in contrast to trained rainbow trout, steelhead and brook char, which oriented relative to the plane of polarized light. Trained fish showed no orientation response when a diffuser was used to depolarize the light source. Rainbow trout trained to orient parallel to a polarization axis in the laboratory were tested under natural skylight before sunset. These fish oriented parallel to the bearing of maximally polarized light in the celestial hemisphere. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.
What can fish see? This is the central question of this chapter. To find out what a human perceives is (although our colleagues in the field of human psychophysics will undoubtedly disagree) a relatively easy task: all you have to do is ask them! It is difficult to apply a comparable criterion to animals. Given the fact that fish cannot speak, one has to rely on monitoring some form of behaviour that is modulated by visual stimuli to find out what the fish can see.
This article has 2 objectives. The 1st is to present necessary and sufficient conditions for the validity of traditional within-S
F tests in repeated measures designs. It is shown that the Mauchly sphericity criterion (
W) and possibly the Box test for the equality of covariance matrices are appropriate to judge the validity of these conditions. Valid applications of both tests are conducted on sets of orthogonal normalized variables that are associated with each cluster of within-S mean square ratios. The 2nd objective of the article is to present empirical results on the appropriateness of using the
W criterion when the variates are not normally distributed. For light-tailed distributions the
W criterion was shown to be moderately conservative, whereas for heavy-tailed distributions, empirical Type I error rates exceeded nominal alpha. Since most social science applications typically involve light-tailed rather than heavy-tailed distributions, the
W criterion should provide useful results in most cases. (29 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
To examine the influence of the spectral characteristics of underwater light on spectral sensitivity of the ON and OFF visual pathways, compound action potential recordings were made from retinal ganglion cells of threespine stickleback from different photic regimes. In fish from a red-shifted photic regime (P50 680 nm for downwelling light at 1m), peak sensitivity of both the ON and OFF pathways was limited to long wavelength light (max 600–620). In contrast, the ON pathway of fish from a comparatively blue-shifted (P50 566 nm) photic regime exhibited sensitivity to medium (max 540–560) and long (max 600 nm) wavelengths, while the OFF pathway exhibited peak sensitivity to only medium (max 540 nm) wavelength light. In a third population, where the the ambient light is moderately red-shifted (P50 629 nm), the ON pathway once again exhibited only a long wavelength sensitivity peak at 620 nm, while the OFF pathway exhibited sensitivity to both medium (max 560 nm) and long (max 600–620 nm) wavelength light. These findings suggest that the photic environment plays an integral role in shaping spectral sensitivity of the ON and OFF pathways.
Polarized light sensitivity was examined in single units of the rainbow trout (Oncorhynchus mykiss) torus semicircularis, a sub-tectal visual area with a high degree of ultraviolet sensitivity. First, chromatically isolated torus units with inputs from each of the four cone mechanisms found in the trout visual system were separately examined for e-vector sensitivity. UV ON-response units showed polarization sensitivity for vertical ly (0 and 180) polarized stimuli, while ON-response units of the short, middle and long cone mechanisms were not polarization sensitive. No OFF-response units of the UV or short cone mechanism were observed, but OFF-response units of the middle and long cone mechanisms show polarization sensitivity for horizontally (90) polarized stimuli. Second, e-vector sensitivity was observed in color-coded units which received inputs from more than one cone mechanism and showed different sign responses (ON or OFF) at different points of the spectral sensitivity curve. Biphasic units which had ON input from the UV cone mechanism and OFF inputs from the middle and long cone mechanisms showed polarization opponency. This opponency was observed with a 380 nm stimulus when the threshold sensitivities of the alpha-band absorption peak of the UV mechanism and the beta-band absorption peak of the middle and long cone mechanisms were equal. We believe that biphasic torus units provide a possible cellular basis for polarized light vision in rainbow trout.
Integrated spike activity of axons from the optic nerve was measured in an investigation of the e-vector sensitive mechanism underlying the ability of rainbow trout (Oncorhynchus mykiss) for orientation in downwelling, linearly-polarized light. In anaesthetized, immobilized fish, one eye was exposed to incremental light flashes which were superimposed over closely controlled background conditions. Under scotopic and various photopic conditions, intensity/response curves were generated from the on-response of the optic nerve. Relative sensitivity curves were then obtained as a function of e-vector direction for the 5 kinds of receptor cells in this trout's retina: rods, ultraviolet cones (UV), short wavelength cones (S), medium wavelength cones (M), and long wavelength cones (L).Under scotopic conditions, no sensitivity to e-vector was apparent: thus, rods do not mediate polarization sensitivity. Under photopic conditions, parr weighing 8–10 g exhibited e-vector sensitivity in two orthogonal channels. A UV stimulus (380 nm) on a white background evoked a three-peaked response (0, 90, and 180) to the e-vector orientations presented in 30 increments between 0 and 180. In contrast, when the background was illuminated with appropriate short and long wavelength cut-off filters, M-and L-cones showed maximum responses only to the horizontal (90) plane whether they were stimulated at their -absorption band or their -absorption band in the near UV. Isolated UV-cones gave maximum responses to the vertical (0 and 180) e-vector, thus corresponding to a second channel. The blue sensitive, S-cones, did not show evidence of polarization sensitivity. As well, no evidence of the polarization sensitivity was observed under UV isolating background conditions in larger individuals, 50–78 g smolts, although the other cone mechanisms responded as in smaller individuals.
DL-2-Amino-4-phosphonobutyric acid (APB) suppresses activity in retinal ON pathways. It is generally assumed that loss of the ON pathway would result in loss of ON responses in the visual system. We tested this assumption by recording activity from the optic nerves of intact goldfish (Carassius auratus) before and after intraocular injection of APB. Whole-nerve responses to increments and decrements of light were compared to electroretinogram responses and to tectal evoked potentials. APB severely reduced the amplitude of the electroretinogram b-wave but left ON and OFF responses from the optic nerve and tectum intact, although decreased in sensitivity. We conclude that APB does not completely eliminate ON responses in the visual system, at least in goldfish. The selectivity and effectiveness of APB must be evaluated in other species before this agent can be relied upon as a useful tool in understanding the roles of ON and OFF pathways in visual function.
The influence of ethambutol on retinal function was studied by recording ganglion cell responses in isolated carp retinas superfused with a Ringer solution containing different concentrations of ethambutol (0 mg/liter, 10 mg/liter, 20 mg/liter, 30 mg/liter). The results indicate that ethambutol reversibly affects color opponency, without changing the sensitivity of the underlying receptor processes. The amacrine and bipolar cells are the most likely candidates to be affected by ethambutol.
Autoradiographic localization of high affinity [3H]glycine uptake in the retina of the goldfish has been used to study some anatomical and physiological properties of potentially glycinergic neurons. There are two classes of retinal cells exhibiting high affinity glycine uptake: Aa amacrine cells and I2 interplexiform cells. Aa amacrine cells constitute about 20% of the somas in the amacrine cell layer and send their dendrites to the middle of the inner plexiform layer. There they are both pre- and postsynaptic primarily to other amacrine cells. Photic modulation of glycine uptake indicates that they are probably red-hyperpolarizing/green-depolarizing neurons. I2 interplexiform cells are a newly discovered type of interplexiform cell; in the outer plexiform layer, they receive direct synaptic input from the somas of red-dominated GABAergic H1 horizontal cells and are apparently presynaptic to dendrites of unidentified types of horizontal cells. The connections of I2 interplexiform cells have not been successfully characterized in the inner plexiform layer. These findings extend our knowledge of neurochemically specific pathways in the cyprinid retina and indicate that glycine, like GABA, is a neurotransmitter primarily involved with circuits coding "red" information.
Color vision in rainbow trout was studied by characterizing the spectral sensitivity of single units in three areas of visual processing: optic nerve; optic tectum; and torus semicircularis. Sensitivity to medium wavelength stimuli was a common feature of all single units examined. Additionally, long wavelength sensitivity was found in all units that were not medium wavelength-only or monophasic. Ultraviolet and short-wavelength sensitivity was common in small, juvenile trout, with ultraviolet sensitive units found in the optic nerve and torus, and short wavelength sensitivity found in the optic nerve and tectum. The shorter wavelength inputs were excitatory and, if found in the same unit, synergistic. The most common type of unit in the trout tectum and optic nerve is trichromatic, with ON inputs from the long and short cone mechanisms and an OFF input from the medium mechanism. In contrast, goldfish color vision is dominated by L and M opponent units without S input. The segregation of ultraviolet sensitivity in the torus but not in the tectum relates to functional differences of these two areas. While the tectum serves the function of wavelength discrimination, ultraviolet inputs to the torus may contribute to prey detection and orientation.
Major themes in neuroethology concern the specificity of key stimuli, neurones tuned to such stimuli, and the release of corresponding behaviour. Neurobiological data from the analysis of visuomotor functions of prey-catching and avoiding in amphibians support the view that retinal outflow in different combinations is pooled for further computation in interacting processing streams, rather than segregated into distinct retinal channels. The keys by which the visual system gets access to perceptual-motor categories are shown to derive from specific computational strategies that evaluate significant configurational features of objects. Rapid behavioural responses are assured by visuomotor pathways which, monitoring different aspects of visual objects, collectively select appropriate motor patterns. Responses can be adapted to varying environmental and internal conditions via modulating and modifying loops. This requires parallel distributed processing and integration at various levels in a macro-network.
The development of photoreceptor cell types and the visual sensitivity of young sockeye salmon were examined. In contrast to previous findings from rainbow trout, rod outer segments were observed in the embryo 1.5 weeks before hatching. At this stage, a full square mosaic with accessory corner cones was visible in the central retina. Post-hatching retinal development is similar to that of other fish species. During the first 11 months of development, the fibrous and interplexiform layers, the outer nuclear layer, the visual cell layer and the retinal pigment epithelium thicken. The ganglion cell layer and the inner nuclear layer regress. In addition, the mean diameter of the cones increases, with that of double cones increasing faster than that of either of the single cone types. As is the case for other salmonids, the density of accessory corner cones diminishes after smoltification (a developmental stage in salmonids). The retina of smolts exhibits a full square mosaic pattern in some peripheral areas and near the central embryonic fissure. However, unlike findings from rainbow trout, compound action potential recordings from the optic nerve of smolt sockeye reveal the presence of four cone mechanisms with sensitivity maxima at 380 (ultraviolet), 425 (short), 520 (middle) and 635 nm (long wavelength). There is also a rod mechanism with maximum sensitivity around 530 nm. Smolts also exhibit polarization sensitivity to 380 nm light under a white crepuscular background.
Some species of fish are able to discriminate, in addition to intensity and wavelength (color), the direction of polarization of visible light. Optical experiments on axially oriented retinal cones from trout and sunfish with use of two types of polarization microscope indicate anisotropic light transmission through paired cones. The measured linear birefringence of paired cone ellipsoids is consistent with the presence of membranous partitions. It is proposed that the partition between the two members of a paired cone, which often appears extensive and flat, functions as a dielectric mirror and that polarization-dependent reflection and refraction at this partition constitutes the underlying mechanism in the transduction of polarization into intensity variation at the photoreceptor's outer segments. We support this hypothesis with linear birefringence and linear dichroism measurements, histological evidence, large-scale optical model measurements, and theoretical calculations based on Fresnel's formulas.
The spectral sensitivities of retinal cones isolated from goldfish (Carassius auratus) retinas were measured in the range 277-737 nm by recording membrane photocurrents with suction pipette electrodes (SPE). Cones were identified with lambda max (+/- S.D.) at 623 +/- 6.9 nm, 537 +/- 4.7 nm, 447 +/- 7.7 nm, and about 356 nm (three cells). Two cells (lambda max 572 and 576 nm) possibly represent genetic polymorphism. A single A2 template fits the alpha-band of P447(2), P537(2), and P623(2). HPLC analysis showed 4% retinal:96% 3-dehydroretinal. Sensitivity at 280 nm is nearly half that at the lambda max in the visible. The lambda max of the beta-band (in nm) is a linear function of the lambda max of the alpha-band and follows the same relation as found for A1-based cone pigments of a cyprinid fish.
In patients with ocular defects caused by the tuberculostaticum ETHAMBUTOL the spectral data obtained under selective chromatic adaptation with psychophysical and electrophysiological methods clearly indicate that signals of all three types of spectrally different cones are present in the visual cortex; however, the signs of color-opponent interactions between the individual cone mechanisms are lacking. Therefore it becomes evident that ETHAMBUTOL mainly affects the function of red/green antagonistic neurons. This method of investigation in patients as described here permits differentiation between toxic alterations affecting the cone receptor and their direct pathways to the visual cortex from those disturbing the action of color-antagonistic mechanisms, upon which chromatic as well as spatial coding strongly relies.
Myambutol führt in einer Dosierung von 25 mg /kg (und mehr) nach Monaten in etwa 1 ½ % der Fälle zu Augenbeteiligungen im Sinne einer retrobulbären Neuritis, seltener einer staubförmigen zentral-parazentralen Pigmentverschiebung in der Netzhaut und seltener zu Gefäßveränderungen (vorübergehenden Blutungen). Ein Zentralskotom kann monatelang bestehen, ohne daß es zu einer ophthalmoskopisch sichtbaren Veränderung kommt. Es kann später zur weitgehenden Wiederherstellung der Funktion mit normaler Papille oder zum bleibenden Skotom mit temporaler Abblassung kommen.
The ability of teleosts to respond to the place of polarized light was determined by theri heart beat rate. When the plane of polarized light was changed, apparent cardiac deceleration was observed in tilapia, rainbow trout, and yellowtail, but there was no response in common carp and crimson sea-bream. To determine which organ perceives polarized light, the eye or the pineal organ, one or both were covered in some tests on tilapia and rainbow trout. The response disappeared when their eyes were covered. The fishes that respond posses polarized light vision, and polarized light is perceived by the eye.
This study was concerned with the problem of how sockeye smolts (Oncorhynchus nerka) find their way out of lake systems during their migration from the nursery areas to the outlet. A general survey of the basic preferred directions and of the reference cues involved in direction finding is presented. /// Die vorliegende Arbeit behandelt die Frage, wie einjährige Sockeye-Lachse (Oncorhynchus nerka) ihren Weg von ihren Geburtsstätten zur Mündung des betreffenden Seensystems ins Meer finden. Es wird eine allgemeine Übersicht der bevorzugten Richtungen und der massgeblichen Richtmarken gegeben.
Food-conditioning experiments conducted in the laboratory demonstrated that groups of yearling sockeye salmon (Oncorhynchus nerka) can discriminate between vertical and horizontal planes of linearly polarized light. Removal of the adipose eyelid, a possible analyser of polarized light, did not abolish the response. The findings support the hypothesis that these fish can use polarization patterns for orientation during their seaward migration.
The results of this study demonstrate that trout (Salmo gairdneri) are capable of orienting to polarized light fields. The spectral composition of the polarized light fields can significantly influence the orientation of trout. Rainbow trout exhibit ontogenetic losses in orientation to polarized light fields which appears coincident with the ontogenetic loss of the UV-sensitive cones. Trout were trained to swim to a refuge located at one end of the training tank under a polarized light field. The E-vector of the polarized light field was oriented parallel or perpendicular to the long axis of the training tank. Trained fish were released in a circular test tank and their angular response scored. Under a white plus ultraviolet polarized light field, trout oriented in the trained E-vector orientation. For instance, fish trained under a parallel E-vector orientation exhibited angular responses close to parallel in the test tank. However, when the spectral composition of the polarized light field was manipulated, the accuracy of spatial orientation of the trout varied. Trout weighing about 30 g exhibited accurate orientation to the white plus UV polarized light field. The trout were incapable of orientation at a body weight of 50 to 60 g.
Thesis (Ph. D.)--University of Victoria, 1998. Includes bibliographical references.
In patients treated with EMB, disturbances in colour vision may be the first and only symptoms of the onset of toxic damage to the optic nerves. Owing to its sensitivity, the Farnsworth 100-Hue test is of great value in the ophthalmic control examinations. Moreover, it permits observation of the dynamics of the toxic process. The three reported cases of damage to the optic nerves confirm the great importance of colour vision examinations, as regards the detection of the complications of EMB treatment.
Small (< 30 g) juvenile rainbow trout (Oncorhynchus mykiss) possess retinal photoreceptor mechanisms sensitive to ultraviolet (UV), short (S), middle (M) and long (L) wavelengths. During normal development, the sensitivity peak of the UV cone mechanism (360 nm) shifts towards the S-wavelengths (to an intermediate lambda max of 390 nm) until, at approx. 60 g, individuals are no longer sensitive in the UV (only a S-wavelength peak at 430 nm remains). This shift in spectral sensitivity is associated with the loss of small accessory corner cones from the retinal photoreceptor cell mosaic. Treating small (< 30 g) rainbow trout with thyroid hormone induced a precocial loss of UV photosensitivity and an associated change in the retinal photoreceptor cell mosaic, identical to the events that occur during normal development.
To answer the question whether, like man, ethambutol treated fish would become color-blind, wavelength discrimination was measured behaviorally in goldfish, preceding, during and after ethambutol treatment. The results are that of the three high discrimination abilities at around 400, 500 and 600 nm, ethambutol affected the latter one. Red-green discrimination is lost reversibly leaving the discriminations in the blue-green and violet range unaffected. This red-green discrimination deficiency cannot be accounted for by a loss of long wavelength cones since the ERG and luminosity functions remain unaffected. Intracellular horizontal cell recordings in goldfish show that ethambutol hyperpolarizes all three types of cone driven horizontal cells and changes their color coding such that their spectral characteristics become cone-like as is the case in dark adapted retina. So, the initial effect induced by ethambutol seems to be an adaptation deficiency in color vision related tasks. Human wavelength discrimination and increment threshold spectral sensitivity functions obtained at low luminance levels are compared to behavioral functions in ethambutol treated goldfish. The high similarity between the ethambutol effects in man and goldfish, and the effects observed in the horizontal cell responses in goldfish are highly indicative that horizontal cells play a key role in color vision. So far their function has been puzzling.
The vertebrate retina processes visual information in parallel neural pathways known as the ON and OFF pathways. These pathways encode increments and decrements of light independently as excitatory responses. We examined the photopic spectral response of ON and OFF mechanisms in goldfish by measuring the sensitivity of optic nerve responses to the onset and termination of stimuli of various wavelengths. Using various adapting backgrounds, we found that the ON and OFF responses have different spectral sensitivities. The weighting of the cone inputs to the responses was estimated by an algebraic summation model. This model suggests that for the ON response, input from S-cones is stronger and more independent than for the OFF response, and M- and L-cones show stronger antagonism in the ON response than in the OFF response. The OFF response probably receives input from all cone types, but spectral antagonism is weak and its dominant input is from L-cones.
The present study examines the changes in ultraviolet (UV) photosensitivity that occur during the growth of rainbow trout (Salmo gairdneri). A comparison of the ocular media transmission of small (n = 3) and large (n = 3) trout eyes did not reveal large changes in the transmission of UV radiation through the eye. We used the heart-rate conditioning technique to measure spectral sensitivity in immobilized trout. Four trout, each weighing less than 30 g, exhibited a UV-sensitivity peak at 360 nm while four additional trout weighing more than 60 g each exhibited no evidence of UV sensitivity. Spectral-sensitivity measurements of two trout weighing 44 g and 60 g revealed UV sensitivity, but when measured one month later (after a 25% increase in body weight) both fish exhibited no UV-sensitivity peak. At this time their sensitivity appeared to conform to the known blue-sensitive cone mechanism.
In the mammalian eye, the ON-centre and OFF-centre retinal ganglion cells form two major pathways projecting to central visual structures from the retina. These two pathways originate at the bipolar cell level: one class of bipolar cells becomes hyperpolarized in response to light, as do all photoreceptor cells, and the other class becomes depolarized on exposure to light, thereby inverting the receptor signal. It has recently become possible to examine the functional role of the ON-pathway in vision by selectively blocking it at the bipolar cell level using the glutamate neurotransmitter analogue 2-amino-4-phosphonobutyrate (APB)1. APB application to monkey, cat and rabbit retinas abolishes ON responses in retinal ganglion cells, the lateral geniculate nucleus and the visual cortex but has no effect on the centre-surround antagonism of OFF cells or the orientation and direction selectivities in the cortex2-5. These and related findings6-11 suggest that the ON and OFF pathways remain largely separate through the lateral geniculate nucleus and that in the cortex, contrary to some hypotheses, they are not directly involved in mechanisms giving rise to orientation and direction selectivities. We have examined the roles of the ON and OFF channels in vision in rhesus monkeys trained to do visual detection and discrimination tasks. We report here that the ON channel is reversibly blocked by injection of APB into the vitreous. Detection of light increment but not of light decrement is severely impaired, and there is a pronounced loss in contrast sensitivity. The perception of shape, colour, flicker, movement and stereo images is only mildly impaired, but longer times are required for their discrimination. Our results suggest that two reasons that the mammalian visual system has both ON and OFF channels is to yield equal sensitivity and rapid information transfer for both incremental and decremental light stimuli and to facilitate high contrast sensitivity.
1. Receptive fields of colour‐coded ganglion cells of the goldfish retina were investigated.
2. Only a few cells (5%, Type P) were found to be as simple as those described by Wagner, MacNichol & Wolbarsht (1960, 1963), with an ‘on’ response to red light in the centre, and an ‘off’ response to green light over a rather wider area, or vice versa.
3. Most cells (49%, Type O) also gave a peripheral response with an ‘on’ response to green light, and an ‘off’ response to red light in the periphery, as well as an ‘on’ response to red light and an ‘off’ response to green light in the centre (or vice versa).
4. When a small spot of light was used to stimulate the periphery of a Type O cell, the peripheral response usually was not obtained. The organization of the periphery is such that a stimulus of large area and low intensity (annulus) is much more effective than a stimulus having equal energy with small area and high intensity (spot). If only small spots are used, the Type O cell is indistinguishable from the Type P cell.
5. Spectral sensitivity measurements show that one central and one peripheral process are fed primarily by red‐absorbing cones, and the other central and the other peripheral process by green‐absorbing cones or rods.
6. The diameter of the receptive field as a whole is very large, being 5 mm or more on the retina.
7. When red spots in green surrounds, or red/green boundaries are used as stimuli, the response can be predicted by summing the responses to the components of the stimulus.
8. This type of receptive field organization is appropriate to mediate simultaneous colour contrast. The ‘opponent colour’ organization previously reported is appropriate for successive colour contrast, but not for simultaneous colour contrast.
9. The component of the response coming from the green‐absorbing cones was masked or hidden by the component of the response coming from the red‐absorbing cones in 14% of the units (Type Q units). The component from the green‐absorbing cones was revealed by using a high intensity of stimulation, or by observing the response after bleaching pigment with an intense red light.
Ethambutol, a tuberculostatic drug, induces red-green colour vision defects in man and goldfish. The ethambutol-induced red-green colour vision defect in goldfish was argued to originate in the retina because after ethambutol application: (1) inhibitive interactions in red-green (double) opponent ganglion cells are lost [Van Dijk & Spekreijse, 1982 (Investigative Ophthalmology and Visual Science, 24, 128-133); Wietsma & Spekreijse, 1992 (Investigative Ophthalmology and Visual Science Suppl., 33, 1032)] and (2) the depolarizing responses to red light in the biphasic horizontal cells are reduced. To account for these findings Spekreijse, Wietsma and Neumeyer [(1991) Vision Research, 31, 551-562] suggested that ethambutol induced dark adaptation in the retina. In this paper the dark adaptation hypothesis is tested with the following results: (1) ethambutol changes only transiently the receptive field size and spectral sensitivity of horizontal cells; (2) the spectral characteristics of horizontal cells do not change in long-term ethambutol-treated goldfish; (3) formation of spinules on horizontal cell dendrites in cone terminals, a parameter for light adaptation, remains unaffected. Therefore we conclude that ethambutol does not induce functional dark adaptation of horizontal cells and that the ethambutol-induced red-green colour vision deficiency does not originate in the horizontal cell layers.
The spectral sensitivity of single units in the torus semicircularis (TS) of small (< 30 g) and large (> 60 g) juvenile rainbow trout, Oncorhynchus mykiss, was investigated. All examined units (n = 39) showed inputs from the long and medium cone mechanisms. In addition, a majority of units (28 of 39) in both size groups of fish had inputs from the UV cone mechanism, and both groups had several types of color-coded units. The TS of large trout differed from small fish by having a significantly higher proportion of luminance or non-color-coded units relative to color-coded units. Additionally, large fish had a reduced number of UV-sensitive units and an increased number of short-wavelength-sensitive units relative to small fish.
We investigated retina preparations of young rainbow trout (Oncorhynchus mykiss) with body wt 5-40 g. Rods, single and double cones were measured in side-on orientation by microspectrophotometry, identifying five spectrally distinct visual pigments (or photoreceptors containing mixtures of visual pigments). The mean wavelength of peak absorbance (lambda max) of the alpha-bands were 365 and 434 nm in single cones, 531 and 576 nm in double cones, and 521 nm in the rods. The half-band width (HBW) of the main absorption bands were broader than expected of retinal- (vitamin A1-) based visual pigments, and thus, they were indicative of a mixed chromophore pool derived from both the vitamin A1 and A2 forms. One consequence of the utilization of mixed chromophores is the broadening of the alpha-band absorption in each pigment type. And yet, we obtained exceptionally narrow HBW for the UV-type pigment, when compared with HBW values expected on the basis of the linear trend seen in visual pigments absorbing in the visible spectrum. We conclude that the UV pigment in rainbow trout has an unusually narrow HBW. Nevertheless, this species is not exceptional in this regard, for the UV-absorbing visual pigments in other vertebrate species also have narrow HBW.
Because the glutamate analog 2-amino-4-phosphonobutyric acid (APB) alters synaptic transmission at the outer plexiform layer in goldfish we asked whether intraocular injection of ABP would alter the spectral sensitivity of the retina. The spectral sensitivity of the ON and OFF components of the optic nerve response (ONR) in goldfish was measured in the presence and absence of APB, under four chromatic adaptation condition. APB decreased absolute sensitivity and altered spectral sensitivity for both ON and OFF responses under each adaptation condition. The spectral sensitivity of the OFF response was altered most at short wavelengths, in a manner consistent with a change in the balance of additive cone inputs. For the ON response, the effects of APB were consistent with a change in spectral antagonism, particularly between M- and L-cones. These results suggest that the activity in the retinal cone pathways in goldfish can be influenced by a mechanism incorporating an APB-sensitive receptor, and that this receptor may be intimately involved with setting the balance of cone inputs to spectrally-opponent neurons.
This study presents evidence of ultraviolet (UV) sensitive, ON center ganglion cells in the fish retina. We determined the spectral sensitivity of ON and OFF responses from the optic nerve mass potential in small (18.0 - 28.5 g) and large (59.5-835 g) rainbow trout, with special reference to UV sensitivity. Under a mid+long-wavelength adapting background, the ON response of small fish revealed the presence of a UV cone mechanism (lambda max 390 nm) which was absent in large specimens. Under similar background conditions, the OFF response of both small and large fish showed one sensitivity peak, dominated by inputs from an M-cone mechanism. An almost complete absence of the accessory corner cones from the retinal mosaic was correlated with the loss of UV sensitivity.
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Ethambutol changes the color coding of carp retinal ganglion cell reversibly. In6estigati6e Opthamology and Vision Science
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