PDF(Pubmed)
Abstract：
The ambient daylight variation is coded by melanopsin photoreceptors and their luxotonic activity increases towards midday when colour temperatures are cooler, and irradiances are higher. Although melanopsin and cone photoresponses can be mediated via separate pathways, the connectivity of melanopsin cells across all levels of the retina enables them to modify cone signals. The downstream effects of melanopsin-cone interactions on human vision are however, incompletely understood. Here, we determined how the change in daytime melanopsin activation affects the human cone pathway signals in the visual cortex. A 5-primary silent-substitution method was developed to evaluate the dependence of cone-mediated signals on melanopsin activation by spectrally tuning the lights and stabilizing the rhodopsin activation under a constant cone photometric luminance. The retinal (white noise electroretinogram) and cortical responses (visual evoked potential) were simultaneously recorded with the photoreceptor-directed lights in 10 observers. By increasing the melanopsin activation, a reverse response pattern was observed with cone signals being supressed in the retina by 27% (p = 0.03) and subsequently amplified by 16% (p = 0.01) as they reach the cortex. We infer that melanopsin activity can amplify cone signals at sites distal to retinal bipolar cells to cause a decrease in the psychophysical Weber fraction for cone vision.
摘要：
环境日光变化由黑视素光感受器编码，当色温较凉爽时，它们的xuxotonic活性在中午增加，辐照度更高。虽然黑视素和视锥光反应可以通过单独的途径介导，黑视素细胞在视网膜各级的连接使它们能够修改视锥信号。然而，黑视素-视锥相互作用对人类视觉的下游影响是，不完全理解。这里,我们确定了白天黑视蛋白激活的变化如何影响视觉皮层中的人类视锥通路信号。开发了一种5主要的沉默取代方法，通过光谱调谐光并在恒定的视锥光度亮度下稳定视紫红质激活来评估视锥介导的信号对黑视素激活的依赖性。视网膜（白噪声视网膜电图）和皮层反应（视觉诱发电位）同时记录了10个观察者的光感受器定向光。通过增加黑素激活，观察到相反的反应模式，视锥信号在视网膜中被抑制了27％（p=0.03），随后在到达皮质时被放大了16％（p=0.01）。我们推断，黑视素活性可以放大视网膜双极细胞远端的视锥信号，从而导致视锥视觉的心理物理韦伯分数降低。
