A NEURAL AND COMPUTATIONAL MODEL FOR THE CHROMATIC CONTROL OF ACCOMMODATION

被引:49
作者
FLITCROFT, DI [1 ]
机构
[1] UNIV OXFORD, PHYSIOL LAB, OXFORD OX1 3PT, ENGLAND
基金
英国惠康基金;
关键词
ACCOMMODATION; CHROMATIC CUES; COLOR OPPONENT; COMPUTATIONAL MODEL;
D O I
10.1017/S0952523800000705
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Accommodation is more accurate with polychromatic stimuli than with narrowband or monochromatic stimuli. The aim of this paper is to develop a computational model for how the visual system uses the extra information in polychromatic stimuli to increase the accuracy of accommodation responses. The proposed model is developed within the context of both trichromacy and also the organization of spatial and chromatic processing within the visual cortex. The refractive error present in the retinal image can be estimated by comparing image quality with and without small additional changes in refractive state. In polychromatic light, the chromatic aberration of the eye results in differences in ocular refractive power for light of different wavelenghts. As a result, the refractive state of the eye can be estimated by comparing image quality in the three types of cone photoreceptor. The ability of cortical neurons to perform such comparisons on image quality with a crude form of spatial-frequency analysis is examined theoretically. It is found that spatially band-pass chromatically opponent neurons (that may correspond to double opponent neurons) can perform such calculations and that chromatic cues to accommodation are extracted most effectively by neurons responding to spatial frequencies of between 2 and 8 cycles/deg.
引用
收藏
页码:547 / 555
页数:9
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