Schefrin B E, Bieber M L, McLean R, Werner J S
Department of Psychology, University of Colorado, Boulder 80309-0345, USA.
J Opt Soc Am A Opt Image Sci Vis. 1998 Feb;15(2):340-8. doi: 10.1364/josaa.15.000340.
The maximal area of complete scotopic spatial summation (Ricco's area) was determined for 50 subjects ranging in age from 19 to 87 yr. Increment thresholds were measured for 10-ms, 520-nm circular test lights of varying diameters that were superimposed and concentric with a 10 degrees, 640-nm circular background. The test lights were imaged in Maxwellian view along the horizontal meridian, 6 degrees nasal from a foveal fixation point. The results demonstrate a statistically significant enlargement of Ricco's area with age. The average angular subtenses of Ricco's areas for the ten youngest (mean = 26 yr) and ten oldest (mean = 75 yr) observers were approximately 48 and 69 arc min, respectively. Model simulations based on a series of optical transfer functions of the eye and varying degrees of intraocular light scatter for younger and older observers show that preneural factors cannot account for these results. Therefore changes in neural mechanisms must be invoked to explain the enlargement in the size of Ricco's area under scotopic conditions.
我们测定了50名年龄在19岁至87岁之间受试者的完全暗视空间总和的最大面积（里科面积）。测量了不同直径的10毫秒、520纳米圆形测试光的增量阈值，这些测试光与10度、640纳米的圆形背景叠加且同心。测试光沿水平子午线在马克斯韦尔视野中成像，位于距中央凹注视点鼻侧6度处。结果表明，里科面积随年龄增长在统计学上有显著增大。年龄最小的十名（平均年龄 = 26岁）和年龄最大的十名（平均年龄 = 75岁）观察者的里科面积的平均视角分别约为48和69角分。基于一系列眼睛的光学传递函数以及针对年轻和年长观察者不同程度的眼内光散射进行的模型模拟表明，神经前因素无法解释这些结果。因此，必须引入神经机制的变化来解释暗视条件下里科面积大小的增大。
