Document Detail


Foveal spatial summation in human cone mechanism.
MedLine Citation:
PMID:  21513184     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
We measured at the fovea the chromatic contrast threshold for stimuli modulated along different chromatic directions in the isoluminant plane of MBDKL colour space, considering the two cardinal axes (L/M) and S/(L + M) and other intermediate non-cardinal directions. This psychophysical determination was conducted as a function of stimulus size. The test stimulus was a foveal isoluminant Gaussian patch with a raised cosinusoidal temporal profile superimposed on a neutral background. The task was performed binocularly. The increment threshold was measured for three observers by a Bayesian adaptive psychometric method (QUEST). The Ricco area of complete spatial summation was estimated from the threshold-versus-area curves. The perceptive fields are smaller for the L/M-cone opponent direction than the S/(L + M)-cone opponent. The perceptive field sizes for the stimuli in non-cardinal chromatic directions and stimuli modulated at the (L/M)-cone opponent direction present similar values. Measurements were made at two luminance levels, 5 and 40 cd m(-2), but the differences found were small. The perceptive field sizes found could be associated with LGN area.
Authors:
Beatriz M O'Donell; Elisa M Colombo
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Perception     Volume:  40     ISSN:  0301-0066     ISO Abbreviation:  Perception     Publication Date:  2011  
Date Detail:
Created Date:  2011-04-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372307     Medline TA:  Perception     Country:  England    
Other Details:
Languages:  eng     Pagination:  50-62     Citation Subset:  IM    
Affiliation:
Departamento de Luminotecnia Luz y Visión "Ing. Herberto C. Bühler", Facultad de Ciencias Exactas y Tecnologia, Universidad Nacional de Tucumán, Av. Independencia 1800, San Miguel de Tucumán, Argentina. bodonell@herrera.unt.edu.ar
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