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Ricco's areas for S‐ and L‐cone mechanisms across the retina
Author(s) -
Volbrecht Vicki J.,
Shrago Erin E.,
Schefrin Brooke E.,
Werner John S.
Publication year - 2000
Publication title -
color research and application
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 62
eISSN - 1520-6378
pISSN - 0361-2317
DOI - 10.1002/1520-6378(2001)26:1+<::aid-col8>3.0.co;2-v
Subject(s) - cone (formal languages) , retina , eccentricity (behavior) , concentric , mathematics , physics , ganglion , optics , geometry , anatomy , biology , algorithm , political science , law
The purposes of this study were to measure areas of complete spatial summation (i.e., Ricco's area) for S‐ and L‐cone mechanisms and to evaluate whether the sizes of Ricco's area could be explained in terms of either the densities of photoreceptors or ganglion cells. Increment thresholds were measured at the fovea and at 1.5°, 4°, 8°, and 20° in the superior retina using a temporal two‐alternative forced‐choice procedure. Test stimuli ranging from −0.36 to 4.61 log area (min 2 ) were presented on concentric 12.3° adapting and auxiliary fields, which isolated either an S‐ or L‐cone mechanism on the plateau of the respective threshold vs. intensity function. The data indicate that from 0–20° retinal eccentricity, the size of Ricco's area is larger for the S‐cone mechanism than the L‐cone mechanism, increases monotonically for the L‐cone mechanism, and, for both cone mechanisms, increases between 8–20° retinal eccentricity. This latter finding suggests that ganglion cell density rather than cone density defines the size of Ricco's area in the parafoveal and peripheral retina. © 2000 John Wiley & Sons, Inc. Col Res Appl, 26, S32–S35, 2001