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Achromatic impulses unmask L‐ and M‐cone adaptive mechanisms
Author(s) -
Zele Andrew J,
Vingrys Algis J
Publication year - 2001
Publication title -
clinical and experimental ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.3
H-Index - 74
eISSN - 1442-9071
pISSN - 1442-6404
DOI - 10.1046/j.1442-9071.2001.00403.x
Subject(s) - achromatic lens , chromatic adaptation , physics , optics , luminance , chromatic scale , foveal , adaptation (eye) , wavelength , medicine , ophthalmology , retinal
The mechanisms underlying the adaptive response for achromatic impulses seen on achromatic fields were investigated. Foveal thresholds were measured for a static probe‐impulse under two conditions of adaptation. Thresholds were obtained under gain‐clamped conditions after observers had reached steady‐state adaptation and with a probe‐flash paradigm. It was found that thresholds isolated on steady‐state fields cannot be modelled using a single mechanism. Likewise, the probe‐flash condition failed to reflect the response of a single mechanism. Both threshold functions showed distinct breaks occurring at about the same field luminance (approximately 1.0 log cd/m 2 ). Optimum data fits required the incorporation of two mechanisms implying the existence of independent processes mediating detection. Chromatic isolation confirmed that differential adaptation had been unmasked in the long‐ and medium‐wavelength sensitive cone inputs to the achromatic channel.