INSERM, CNRS, Insititut de la Vision, Sorbonne Université, 17 Rue Moreau, 75012, Paris, France.
Laboratoire Psychophysique de la Vision, École d'optométrie, Université de Montréal, Montréal, QC, Canada.
Sci Rep. 2020 Oct 5;10(1):16521. doi: 10.1038/s41598-020-73322-7.
Motion perception is affected by healthy aging, which impairs the ability of older adults to perform some daily activities such as driving. The current study investigated the underlying causes of age-related motion contrast sensitivity losses by using an equivalent noise paradigm to decompose motion contrast sensitivity into calculation efficiency, the temporal modulation transfer function (i.e., temporal blur) and 3 sources of internal noise: stochastic absorption of photons by photoreceptors (i.e., photon noise), neural noise occurring at the retinal level (i.e., early noise) and at the cortical level (i.e., late noise). These sources of internal noise can be disentangled because there impacts on motion contrast sensitivity vary differently as a function of luminance intensity. The impact of healthy aging on these factors was evaluated by measuring motion contrast sensitivity of young and older healthy adults at different luminance intensities, temporal frequencies and with/without external noise. The older adults were found to have higher photon noise, which suggests a lower photon absorption rate of cones. When roughly equating the amount of photons being absorbed by the photoreceptors, older adults had lower calculation efficiencies, but no significant aging effect was found on temporal modulation transfer function, early noise and late noise.
运动感知会受到健康衰老的影响，这会损害老年人执行某些日常活动的能力，例如驾驶。本研究通过使用等效噪声范式将运动对比敏感度分解为计算效率、时变调制传递函数（即时间模糊）和 3 种内部噪声源：光感受器中光子的随机吸收（即光子噪声）、视网膜水平（即早期噪声）和皮质水平（即晚期噪声）发生的神经噪声，以此探究与年龄相关的运动对比敏感度损失的潜在原因。这些内部噪声源可以被区分开来，因为它们对运动对比敏感度的影响随亮度强度的不同而不同。通过测量不同亮度强度、时间频率以及有无外部噪声下年轻和老年健康成年人的运动对比敏感度，评估了健康衰老对这些因素的影响。结果发现老年人的光子噪声更高，这表明视锥细胞的光子吸收率较低。当大致相等地估计光感受器吸收的光子数量时，老年人的计算效率较低，但在时变调制传递函数、早期噪声和晚期噪声方面没有发现明显的衰老效应。
