Photopigment basis for dichromatic color vision in the horse.
Abstract: Horses, like other ungulates, are active in the day, at dusk, dawn, and night; and, they have eyes designed to have both high sensitivity for vision in dim light and good visual acuity under higher light levels (Walls, 1942). Typically, daytime activity is associated with the presence of multiple cone classes and color-vision capacity (Jacobs, 1993). Previous studies in other ungulates, such as pigs, goats, cows, sheep and deer, have shown that they have two spectrally different cone types, and hence, at least the photopigment basis for dichromatic color vision (Neitz & Jacobs, 1989; Jacobs, Deegan II, Neitz, Murphy, Miller, & Marchinton, 1994; Jacobs, Deegan II, & Neitz, 1998). Here, electroretinogram flicker photometry was used to measure the spectral sensitivities of the cones in the domestic horse (Equus caballus). Two distinct spectral mechanisms were identified and are consistent with the presence of a short-wavelength-sensitive (S) and a middle-to-long-wavelength-sensitive (M/L) cone. The spectral sensitivity of the S cone was estimated to have a peak of 428 nm, while the M/L cone had a peak of 539 nm. These two cone types would provide the basis for dichromatic color vision consistent with recent results from behavioral testing of horses (Macuda & Timney, 1999; Macuda & Timney, 2000; Timney & Macuda, 2001). The spectral peak of the M/L cone photopigment measured here, in vivo, is similar to that obtained when the gene was sequenced, cloned, and expressed in vitro (Yokoyama & Radlwimmer, 1999). Of the ungulates that have been studied to date, all have the photopigment basis for dichromatic color vision; however, they differ considerably from one another in the spectral tuning of their cone pigments. These differences may represent adaptations to the different visual requirements of different species.
Publication Date: 2003-04-08 PubMed ID: 12678603DOI: 10.1167/1.2.2Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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This research documents the photopigment basis for dichromatic color vision in horses. The study identified the presence of two distinct spectral mechanisms, which provides indications for horses having color vision.
Introduction to the Research
- The study begins by indicating that horses, like other ungulates, are active at all times of the day, such as daytime, dusk, dawn, and night, necessitating high visual acuity and sensitivity in various light levels.
- It is commonly associated that daytime activities require the presence of multiple cone classes and the capacity for color vision.
- The research refers to past studies conducted on other ungulates that like horses, including pigs, goats, cows, sheep, and deer, all of which were found to have two spectrally different cone types as well.
Research Methodology
- The study used electroretinogram flicker photometry to measure the spectral sensitivities of the cones in the eyes of the domestic horse, Equus caballus.
- This experimental approach helped identify two distinct spectral mechanisms in horses’ eyes.
Research Findings
- These two distinct spectral mechanisms are labeled as a short-wavelength-sensitive (S) and a middle-to-long-wavelength-sensitive (M/L) cone.
- Further measurements revealed that the spectral sensitivity of the S cone peak was at 428 nm, while the M/L cone peak was at 539 nm.
- These two types of cones are suggested to provide the basis for dichromatic color vision, which is in line with the results from previous behavior testing studies on horses.
Interpretation and Conclusion
- The spectral peak of the M/L cone photopigment measured in vivo (in the living horse) was found to be similar to the peak obtained when the gene was sequenced, cloned, and expressed in vitro (outside the body).
- The study concludes that all studied ungulates have displayed the photopigment basis for dichromatic color vision, but there is a noticeable variation in the spectral tuning of their cone pigments.
- The differences observed across different species are speculated to be adaptations to different visual requirements.
Cite This Article
APA
Carroll J, Murphy CJ, Neitz M, Hoeve JN, Neitz J.
(2003).
Photopigment basis for dichromatic color vision in the horse.
J Vis, 1(2), 80-87.
https://doi.org/10.1167/1.2.2 Publication
Researcher Affiliations
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA.
MeSH Terms
- Adaptation, Physiological
- Animals
- Color Perception / physiology
- Electroretinography
- Horses / physiology
- Photic Stimulation
- Retinal Cone Photoreceptor Cells / chemistry
- Retinal Cone Photoreceptor Cells / physiology
- Retinal Pigments / analysis
- Retinal Pigments / physiology
- Vision, Ocular / physiology
- Visual Perception / physiology
Grant Funding
- EY01931 / NEI NIH HHS
- EY09303 / NEI NIH HHS
Citations
This article has been cited 12 times.- Hagen JFD, Roberts NS, Johnston RJ Jr. The evolutionary history and spectral tuning of vertebrate visual opsins.. Dev Biol 2023 Jan;493:40-66.
- Rørvang MV, Nielsen BL, McLean AN. Sensory Abilities of Horses and Their Importance for Equitation Science.. Front Vet Sci 2020;7:633.
- Paul SC, Stevens M. Horse vision and obstacle visibility in horseracing.. Appl Anim Behav Sci 2020 Jan;222:104882.
- Bernauer K, Kollross H, Schuetz A, Farmer K, Krueger K. How do horses (Equus caballus) learn from observing human action?. Anim Cogn 2020 Jan;23(1):1-9.
- Dresp-Langley B, Reeves A. Colour for Behavioural Success.. Iperception 2018 Mar-Apr;9(2):2041669518767171.
- Melin AD, Kline DW, Hiramatsu C, Caro T. Zebra Stripes through the Eyes of Their Predators, Zebras, and Humans.. PLoS One 2016;11(1):e0145679.
- Stephen ID, Mahmut MK, Case TI, Fitness J, Stevenson RJ. The uniquely predictive power of evolutionary approaches to mind and behavior.. Front Psychol 2014;5:1372.
- Ebeling W, Hemmi JM. Dichromatic colour vision in wallabies as characterised by three behavioural paradigms.. PLoS One 2014;9(1):e86531.
- Shinozaki A, Takagi S, Hosaka YZ, Uehara M. The fibrous tapetum of the horse eye.. J Anat 2013 Nov;223(5):509-18.
- Jacobs GH. Evolution of colour vision in mammals.. Philos Trans R Soc Lond B Biol Sci 2009 Oct 12;364(1531):2957-67.
- Roth LS, Balkenius A, Kelber A. The absolute threshold of colour vision in the horse.. PLoS One 2008;3(11):e3711.
- Yokoyama S, Takenaka N, Agnew DW, Shoshani J. Elephants and human color-blind deuteranopes have identical sets of visual pigments.. Genetics 2005 May;170(1):335-44.
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