THE ROLE OF RETINAL OIL DROPLETS IN COLOR VISION IN THE PIGEON.
Item
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Title
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THE ROLE OF RETINAL OIL DROPLETS IN COLOR VISION IN THE PIGEON.
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Identifier
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AAI8629708
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identifier
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8629708
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Creator
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LAIRD, MOLLY.
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Contributor
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James Gordon
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Date
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1986
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Physiological
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Abstract
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The retinas of diurnal birds are characterized by the presence of intensely and vividly pigmented oil droplets located in the inner segments of cones. These droplets are pigmented by carotenoids. In order to clarify the possible role of these oil droplets in color vision, pigeons were reared on a carotenoid-free diet in an attempt to produce birds with colorless oil droplets. Because so much information is available about color vision in normal pigeons, this species seemed a promising subject for investigating the function of oil droplets.;Four normal birds and one bird reared on the diet were compared on a two-alternative forced choice wavelength discrimination task at 600 nm, the pigeon's area of best wavelength discrimination. The normal birds were also tested at 500 and 560 nm. Performance for the normal birds was essentially error-free down to intervals of about 4 nm at wavelengths both longer and shorter than the standard. The carotenoid-deprived bird did not learn the discrimination at wavelengths longer than 600 nm for intervals as large as 20 nm. He did learn to discriminate a wavelength interval of 30 nm between 600 nm and shorter wavelengths, but performance rapidly fell to chance levels at wavelength intervals smaller than 25 nm.;A control for effects of intensity indicated that the birds ignored intensity information until virtually no wavelength information was available. Attempts to train birds on an intensity-only task while holding wavelength constant were only partially successful.;Electroretinographic testing of the retinal red field of the carotenoid-deprived and normal birds indicated that spectral sensitivity fell off much more steeply at wavelengths longer than 620 nm for the carotenoid-deprived than for the normal birds. Maximum sensitivity was shifted to 600 nm compared to 620 nm for the normal birds, and sensitivity was higher at 560 and 540 nm for the carotenoid-deprived bird than for the normal birds.;The amplitude of the ERG responses as well as their waveforms were normal for the carotenoid-deprived bird and provide evidence that retinal elements other than the oil droplets were unaffected by the dietary treatment. Microscopic examination of the experimental bird's retina showed that yellow and orange pigmented oil droplets were present but that the red droplets were absent.;This study indicates that one function of the red cell droplets is to sharpen wavelength discrimination at the spectral area around 600 nm.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Psychology
