Vandewalle Gilles, Collignon Olivier, Hull Joseph T, Daneault Véronique, Albouy Geneviève, Lepore Franco, Phillips Christophe, Doyon Julien, Czeisler Charles A, Dumont Marie, Lockley Steven W, Carrier Julie
University of Montréal Geriatric Institute, Québec, Canada.
J Cogn Neurosci. 2013 Dec;25(12):2072-85. doi: 10.1162/jocn_a_00450. Epub 2013 Jul 16.
Light regulates multiple non-image-forming (or nonvisual) circadian, neuroendocrine, and neurobehavioral functions, via outputs from intrinsically photosensitive retinal ganglion cells (ipRGCs). Exposure to light directly enhances alertness and performance, so light is an important regulator of wakefulness and cognition. The roles of rods, cones, and ipRGCs in the impact of light on cognitive brain functions remain unclear, however. A small percentage of blind individuals retain non-image-forming photoreception and offer a unique opportunity to investigate light impacts in the absence of conscious vision, presumably through ipRGCs. Here, we show that three such patients were able to choose nonrandomly about the presence of light despite their complete lack of sight. Furthermore, 2 sec of blue light modified EEG activity when administered simultaneously to auditory stimulations. fMRI further showed that, during an auditory working memory task, less than a minute of blue light triggered the recruitment of supplemental prefrontal and thalamic brain regions involved in alertness and cognition regulation as well as key areas of the default mode network. These results, which have to be considered as a proof of concept, show that non-image-forming photoreception triggers some awareness for light and can have a more rapid impact on human cognition than previously understood, if brain processing is actively engaged. Furthermore, light stimulates higher cognitive brain activity, independently of vision, and engages supplemental brain areas to perform an ongoing cognitive process. To our knowledge, our results constitute the first indication that ipRGC signaling may rapidly affect fundamental cerebral organization, so that it could potentially participate to the regulation of numerous aspects of human brain function.
光通过内在光敏视网膜神经节细胞（ipRGCs）的输出，调节多种非成像（或非视觉）的昼夜节律、神经内分泌和神经行为功能。暴露于光线下可直接提高警觉性和表现，因此光是清醒和认知的重要调节因素。然而，视杆细胞、视锥细胞和ipRGCs在光对认知脑功能影响中的作用仍不清楚。一小部分盲人保留了非成像光感受能力，这为在没有有意识视觉的情况下研究光的影响提供了独特机会，推测是通过ipRGCs实现的。在这里，我们表明，尽管这三名患者完全失明，但他们能够非随机地选择是否存在光线。此外，在给予听觉刺激的同时施加2秒蓝光，可改变脑电图活动。功能磁共振成像进一步显示，在听觉工作记忆任务期间，不到一分钟的蓝光就会促使参与警觉性和认知调节的前额叶补充区和丘脑脑区以及默认模式网络的关键区域被激活。这些结果必须被视为概念验证，表明非成像光感受能引发对光的某种意识，并且如果大脑处理过程积极参与，对人类认知的影响可能比之前理解的更快。此外，光可独立于视觉刺激更高的认知脑活动，并促使补充脑区参与正在进行的认知过程。据我们所知，我们的结果首次表明ipRGC信号可能会迅速影响基本的大脑组织，从而可能参与调节人类脑功能的众多方面。
