Cyclotron Research Centre, University of Liège-Sart Tilman, Liège, Belgium.
J Biol Rhythms. 2011 Jun;26(3):249-59. doi: 10.1177/0748730411401736.
Light is a powerful modulator of cognition through its long-term effects on circadian rhythmicity and direct effects on brain function as identified by neuroimaging. How the direct impact of light on brain function varies with wavelength of light, circadian phase, and sleep homeostasis, and how this differs between individuals, is a largely unexplored area. Using functional MRI, we compared the effects of 1 minute of low-intensity blue (473 nm) and green light (527 nm) exposures on brain responses to an auditory working memory task while varying circadian phase and status of the sleep homeostat. Data were collected in 27 subjects genotyped for the PER3 VNTR (12 PER3(5/5) and 15 PER3(4/4) ) in whom it was previously shown that the brain responses to this task, when conducted in darkness, depend on circadian phase, sleep homeostasis, and genotype. In the morning after sleep, blue light, relative to green light, increased brain responses primarily in the ventrolateral and dorsolateral prefrontal cortex and in the intraparietal sulcus, but only in PER3(4/4) individuals. By contrast, in the morning after sleep loss, blue light increased brain responses in a left thalamofrontoparietal circuit to a larger extent than green light, and only so in PER3(5/5) individuals. In the evening wake maintenance zone following a normal waking day, no differential effect of 1 minute of blue versus green light was observed in either genotype. Comparison of the current results with the findings observed in darkness indicates that light acts as an activating agent particularly under those circumstances in which and in those individuals in whom brain function is jeopardized by an adverse circadian phase and high homeostatic sleep pressure.
光是一种强大的认知调节剂，它通过对昼夜节律的长期影响和神经影像学所确定的对大脑功能的直接影响来实现这一点。光对大脑功能的直接影响如何随光的波长、昼夜节律相位和睡眠稳态而变化，以及这种影响在个体之间如何不同，这是一个很大程度上尚未探索的领域。使用功能磁共振成像，我们比较了在不同昼夜节律相位和睡眠稳态状态下，1 分钟低强度蓝光（473nm）和绿光（527nm）暴露对听觉工作记忆任务大脑反应的影响。在 27 名被 PER3 VNTR（12 名 PER3(5/5)和 15 名 PER3(4/4)）基因分型的受试者中收集了数据，先前的研究表明，当在黑暗中进行这项任务时，大脑对这项任务的反应取决于昼夜节律相位、睡眠稳态和基因型。在睡眠后的早晨，与绿光相比，蓝光增加了大脑在腹外侧和背外侧前额叶皮层和顶内沟的反应，但仅在 PER3(4/4)个体中。相比之下，在睡眠剥夺后的早晨，蓝光增加了左丘脑-额顶叶回路的大脑反应，其程度大于绿光，而且仅在 PER3(5/5)个体中如此。在正常清醒日之后的夜间清醒维持区，在两种基因型中，1 分钟的蓝光与绿光相比都没有表现出不同的效果。将当前的结果与在黑暗中观察到的结果进行比较表明，光作为一种激活剂，特别是在那些由于不利的昼夜节律相位和高稳态睡眠压力而使大脑功能受到威胁的情况下和那些个体中起作用。
