Bird colour vision: behavioural thresholds reveal receptor noise

2015 ◽  
Vol 218 (2) ◽  
pp. 184-193 ◽  
Author(s):  
P. Olsson ◽  
O. Lind ◽  
A. Kelber
Keyword(s):  
Colour Vision ◽  
Receptor Noise

scholarly journals Thresholds and noise limitations of colour vision in dim light

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160065 ◽  
Author(s):  
Almut Kelber ◽  
Carola Yovanovich ◽  
Peter Olsson
Keyword(s):  
Shot Noise ◽  
Colour Vision ◽  
Absolute Threshold ◽  
Colour Discrimination ◽  
Dark Noise ◽  
Visual Threshold ◽  
Light Intensities ◽  
Purkinje Shift ◽  
Dim Light ◽  
Receptor Noise

Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod–cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones. This article is part of the themed issue 'Vision in dim light’.

scholarly journals Colour thresholds in a coral reef fish

2016 ◽  
Vol 3 (9) ◽  
pp. 160399 ◽  
Author(s):  
C. M. Champ ◽  
M. Vorobyev ◽  
N. J. Marshall
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Colour Vision ◽  
Visible Spectrum ◽  
Reef Fishes ◽  
Colour Discrimination ◽  
Visual Model ◽  
The World ◽  
Different Parts ◽  
Receptor Noise

Coral reef fishes are among the most colourful animals in the world. Given the diversity of lifestyles and habitats on the reef, it is probable that in many instances coloration is a compromise between crypsis and communication. However, human observation of this coloration is biased by our primate visual system. Most animals have visual systems that are ‘tuned’ differently to humans; optimized for different parts of the visible spectrum. To understand reef fish colours, we need to reconstruct the appearance of colourful patterns and backgrounds as they are seen through the eyes of fish. Here, the coral reef associated triggerfish, Rhinecanthus aculeatus , was tested behaviourally to determine the limits of its colour vision. This is the first demonstration of behavioural colour discrimination thresholds in a coral reef species and is a critical step in our understanding of communication and speciation in this vibrant colourful habitat. Fish were trained to discriminate between a reward colour stimulus and series of non-reward colour stimuli and the discrimination thresholds were found to correspond well with predictions based on the receptor noise limited visual model and anatomy of the eye. Colour discrimination abilities of both reef fish and a variety of animals can therefore now be predicted using the parameters described here.

scholarly journals A generalized equation for the calculation of receptor noise limited colour distances in n -chromatic visual systems

2017 ◽  
Vol 4 (9) ◽  
pp. 170712 ◽  
Author(s):  
R. C. Clark ◽  
R. D. Santer ◽  
J. S. Brebner
Keyword(s):  
Colour Vision ◽  
Generalized Equation ◽  
Nervous Systems ◽  
Visual Model ◽  
Visual Systems ◽  
Distance Model ◽  
Similarities And Differences ◽  
Single Formula ◽  
Receptor Noise ◽  
Colour Distance

Researchers must assess similarities and differences in colour from an animal's eye view when investigating hypotheses in ecology, evolution and behaviour. Nervous systems generate colour perceptions by comparing the responses of different spectral classes of photoreceptor through colour opponent mechanisms, and the performance of these mechanisms is limited by photoreceptor noise. Accordingly, the receptor noise limited (RNL) colour distance model of Vorobyev and Osorio (Vorobyev & Osorio 1998 Proc. R. Soc. Lond. B 265 , 351–358 ( doi:10.1098/rspb.1998.0302 )) generates predictions about the discriminability of colours that agree with behavioural data, and consequently it has found wide application in studies of animal colour vision. Vorobyev and Osorio (1998) provide equations to calculate RNL colour distances for animals with di-, tri- and tetrachromatic vision, which is adequate for many species. However, researchers may sometimes wish to compute RNL colour distances for potentially more complex colour visual systems. Thus, we derive a simple, single formula for the computation of RNL distance between two measurements of colour, equivalent to the published di-, tri- and tetrachromatic equations of Vorobyev and Osorio (1998), and valid for colour visual systems with any number of types of noisy photoreceptors. This formula will allow the easy application of this important colour visual model across the fields of ecology, evolution and behaviour.

scholarly journals Colour vision and information theory: the receptor noise-limited model implies optimal colour discrimination by opponent channels

2020 ◽  
Author(s):  
Sebastián Risau-Gusman
Keyword(s):  
Colour Vision ◽  
Theoretical Models ◽  
Ideal Observer ◽  
Discrimination Function ◽  
Colour Discrimination ◽  
Biologically Relevant ◽  
Visual Systems ◽  
The World ◽  
The One ◽  
Receptor Noise

AbstractIn order to interpret animal behaviour we need to understand how they see the world. As colour discrimination is almost impossible to test directly in animals, it is important to develop theoretical models based in the properties of visual systems. One of the most successful is the receptor noise-limited (RNL) model, which depends only on the level of noise in photoreceptors and opponent mechanisms. Here optimal colour discrimination properties are obtained using information theoretical tools, for the early stages of visual systems with and without colour opponent mechanisms. For most biologically relevant conditions the optimal discrimination function of an ideal observer coincides with the one obtained with the RNL model. Many variants of the model can be cast into the same framework, which permits meaningful comparisons across species. For example, it is shown that the presence of opponency seems to be the preferred hypothesis for bees, but not for budgerigars. Since this is a consequence of the presence of oil droplets, this could also be true for most other species of birds.

THE COLOUR VISION DEFICIENCIES AMONG STUDENTS OF HUE SECONDARY SCHOOL OF TRANSPORTATION

2013 ◽  
pp. 76-81
Author(s):  
Thi Anh Thu Nguyen ◽  
Thi Mai Dung Nguyen
Keyword(s):  
Secondary School ◽  
Colour Vision ◽  
Daily Life ◽  
Visual Disabilities ◽  
Occupation Group ◽  
Different Types ◽  
Colour Blindness ◽  
Critical Requirement

Background: Colorblind disability causes difficulties for people in daily life. Derived from the critical requirement to detect the patients in order to help prevent inappropriate careers, especially careers related to transportation, this research aim to determine the situations and the distributions of different types of visual disabilities. Materials: 1174 students (787 boys and 387 girls) including 2 groups: occupation group and transportation group were tested with ISHIHARA chromatic plates for colour vision deficiencies (CVD) (CVD iclude the total colour blindness, red- green blindness, red-blindness, green- blindness). The results are showed as follow: (i) Frequency of CVD boys among boy group is 4.70%; (ii) Frequency of CVD girls among girls group is 2.58%; (iii) In boy group, among 3 types of red- green blindness, the green-blindness has the higher frequency (3.18%) comparision with these ones of the red- green blindness and red-blindness. The total colour defiency was hardly; (iv) Frequency of CVD students among occupation group is 4.15%; (v) Frequency of CVD students among transportation group is 3.83%.

Birds in the Dark: Complementary and Partial Information

2017 ◽  
Author(s):  
Graham R. Martin
Keyword(s):  
Annual Cycle ◽  
Colour Vision ◽  
Partial Information ◽  
Night Time ◽  
Light Levels ◽  
Night Feeding ◽  
Nocturnal Species ◽  
Length Changes

Night-time poses exacting problems for vision, resolution inevitably falls and colour vision is not possible as light levels decrease to those of natural night time. Furthermore, light levels are highly variable depending upon whether there is moonlight, and night length changes dramatically in the annual cycle according to latitude. Few birds exploit the resources available at night. Those that do rely upon information received from vision complemented by information from other senses (hearing, olfaction, and touch), and upon highly specialized and restricted behaviours. However, many birds occasionally exploit night-time, e.g. during migration, arriving and departing from nests, and occasional night feeding. Some seabirds dive to such depths that they experience night-time light levels when foraging. Truly nocturnal species such as owls, kiwi, and oilbirds are highly sedentary, and this is essential to allow them to interpret correctly the partial information that is available to them.

scholarly journals Myopia-26, the female-limited form of early-onset high myopia, occurring in a European family

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Noémi Széll ◽  
Tamás Fehér ◽  
Zoltán Maróti ◽  
Tibor Kalmár ◽  
Dóra Latinovics ◽  
...  
Keyword(s):  
Middle Ages ◽  
Early Onset ◽  
Colour Vision ◽  
High Myopia ◽  
Field Testing ◽  
Cone Dystrophy ◽  
Ophthalmological Examination ◽  
Whole Exome ◽  
Caucasian Family ◽  
Cone System

Abstract Background Female-limited early-onset high myopia, also called Myopia-26 is a rare monogenic disorder characterized by severe short sightedness starting in early childhood and progressing to blindness potentially by the middle ages. Despite the X-linked locus of the mutated ARR3 gene, the disease paradoxically affects females only, with males being asymptomatic carriers. Previously, this disease has only been observed in Asian families and has not gone through detailed investigation concerning collateral symptoms or pathogenesis. Results We found a large Hungarian family displaying female-limited early-onset high myopia. Whole exome sequencing of two individuals identified a novel nonsense mutation (c.214C>T, p.Arg72*) in the ARR3 gene. We carried out basic ophthalmological testing for 18 family members, as well as detailed ophthalmological examination (intraocular pressure, axial length, fundus appearance, optical coherence tomography, visual field- testing) as well as colour vision- and electrophysiology tests (standard and multifocal electroretinography, pattern electroretinography and visual evoked potentials) for eight individuals. Ophthalmological examinations did not reveal any signs of cone dystrophy as opposed to animal models. Electrophysiology and colour vision tests similarly did not evidence a general cone system alteration, rather a central macular dysfunction affecting both the inner and outer (postreceptoral and receptoral) retinal structures in all patients with ARR3 mutation. Conclusions This is the first description of a Caucasian family displaying Myopia-26. We present two hypotheses that could potentially explain the pathomechanism of this disease.

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