The effects of aging on orientation discrimination
The effects of aging on orientation discrimination
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DOI：
10.1016/j.visres.2007.02.016
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发表时间：
2007-06-01
期刊：
影响因子：
1.8
通讯作者：
Bennett, Patrick J.
中科院分区：
文献类型：
--
作者：
Betts, Lisa R.;Sekuler, Allison B.;Bennett, Patrick J.
目前的实验测量了年轻（平均年龄23岁）和年长（平均年龄66岁）受试者的取向歧视阈值。在实验1中，在不同的外部噪声水平下，区分方向不同的Gabor模式（0.75、1.5和3 c/度）所需的对比度为12度。在所有三个空间频率上，当外部噪声较低时，老年人的识别阈值显著高于年轻人，而当外部噪声较高时，则不显著高于年轻人。在实验2中，在固定对比度的情况下，以不同方向的刺激对比度作为判别阈值的函数。所得的阈值对比曲线在两个年龄组中具有非常相似的形状，尽管从老年受试者中获得的曲线偏移到略高的对比。当对比大于0.05时，老年和年轻受试者的阈值大致恒定在0.5度。实验1和2的结果表明，取向歧视的年龄差异仅仅是由于等效输入噪声的差异。使用与实验1相同的方法，实验3测量了6名年轻观察者的阈值作为外部噪声和视网膜照度的函数。虽然降低视网膜照度会增加等效输入噪声，但其影响远小于实验1中发现的年龄差异。因此，取向辨别的差异不太可能仅仅是由于视网膜光照的差异。我们的发现与最近的生理实验一致，这些实验发现衰老猫的视觉皮层神经元的自发活动增加，方向调节减少(Hua， T., Li， X., He， L., Zhou， Y., Wang， Y., Leventhal， A. G.（206）。老年猫视觉皮质细胞的功能退化。神经生物学/神经衰老，27(1),155-162)和猴子(Yu， S., Wang， Y., Li， X., Zhou， Y. & Leventhal， A. G.（2006）。衰老猕猴视觉皮层功能退化。神经科学，140(3),1023-1029；Leventhal， A. G., Wang， Y., Pu， M., Zhou， Y.，和Ma。y(2003)。GABA及其激动剂可改善衰老猴子的视觉皮质功能。科学，300(5620),812-815)。(c) 2007 Elsevier Ltd.版权所有。
The current experiments measured orientation discrimination thresholds in younger (mean age 23 years) and older (mean age 66 years) subjects. In Experiment 1, the contrast needed to discriminate Gabor patterns (0.75, 1.5, and 3 c/deg) that differed in orientation by 12 deg was measured for different levels of external noise. At all three spatial frequencies, discrimination thresholds were significantly higher in older than younger subjects when external noise was low, but not when external noise was high. In Experiment 2, discrimination thresholds were measured as a function of stimulus contrast by varying orientation while contrast was fixed. The resulting threshold-vs-contrast curves had very similar shapes in the two age groups, although the curve obtained from older subjects was shifted to slightly higher contrasts. At contrasts greater than 0.05, thresholds in both older and younger subjects were approximately constant at 0.5 deg. The results from Experiments I and 2 suggest that age differences in orientation discrimination are due solely to differences in equivalent input noise. Using the same methods as Experiment 1, Experiment 3 measured thresholds in 6 younger observers as a function of external noise and retinal illuminance. Although reducing retinal illumination increased equivalent input noise, the effect was much smaller than the age difference found in Experiment 1. Therefore, it is unlikely that differences in orientation discrimination were due solely to differences in retinal illumination. Our findings are consistent with recent physiological experiments that have found elevated spontaneous activity and reduced orientation tuning on visual cortical neurons in senescent cats (Hua, T., Li, X., He, L., Zhou, Y., Wang, Y., Leventhal, A. G. (206). Functional degradation of visual cortical cells in old cats. Neurobio/ogil Aging, 27(1), 155-162) and monkeys (Yu, S., Wang, Y., Li, X., Zhou, Y. & Leventhal, A. G. (2006). Functional degradation of visual cortex in senescent rhesus monkeys. Neuroscience, 140(3), 1023-1029; Leventhal, A. G., Wang, Y., Pu, M., Zhou, Y. & Ma. Y. (2003). GABA and its agonists improved visual cortical function in senescent monkeys. Seience,300 (5620), 812-815). (c) 2007 Elsevier Ltd. All rights reserved.