Melanopsin and rod-cone photoreceptors play different roles in mediating pupillary light responses during exposure to continuous light in humans.
Melanopsin and rod-cone photoreceptors play different roles in mediating pupillary light responses during exposure to continuous light in humans.
复制标题
黑素蛋白和杆孔光感受器在介导人类连续光期间介导瞳孔光反应中起着不同的作用。
DOI：
10.1523/jneurosci.1321-12.2012
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发表时间：
2012-10-10
期刊：
影响因子：
--
通讯作者：
Lockley SW
中科院分区：
文献类型：
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作者：
Gooley JJ;Ho Mien I;St Hilaire MA;Yeo SC;Chua EC;van Reen E;Hanley CJ;Hull JT;Czeisler CA;Lockley SW
在哺乳动物中，瞳孔光反射是由含有黑视素的固有光敏视网膜神经节细胞介导的，这些细胞也接受杆状锥光感受器的输入。为了评估黑视素和杆状锥体光感受器对人类瞳孔光反射的相对贡献，我们比较了视力正常的人（n = 24）和缺乏杆状锥体功能的盲人的瞳孔光反应。在这里，我们表明，在低辐照水平下，正常的瞳孔反应需要视觉光感受器，并且在暴露于视觉光谱的长波长部分的光时，持续的瞳孔收缩需要视觉光感受器。在没有视杆-视锥细胞功能的情况下，瞳孔运动反应缓慢而持续，不能跟踪间歇性的光刺激，这表明视杆/视锥细胞需要编码光强度的快速调制。在视力正常的个体中，在连续低辐照度光照射下，瞳孔收缩至少在30分钟内单调下降，这表明稳态瞳孔反应比先前报道的慢一个数量级。暴露在低辐照度间歇性绿光（543 nm; 0.1-4 Hz）下30分钟，反复激活锥状光感受器，引起持续的瞳孔收缩反应，比暴露在连续绿光下的反应强烈两倍以上。我们的研究结果表明，杆状视锥光感受器和黑视素在调节瞳孔对连续光的反应中起着非冗余的作用。此外，我们的研究结果表明，通过使用间歇性光来反复激活人类的视锥光感受器，可能会增强对低辐照度暴露的非视觉光反应。
In mammals, the pupillary light reflex is mediated by intrinsically photosensitive melanopsin-containing retinal ganglion cells that also receive input from rod-cone photoreceptors. To assess the relative contribution of melanopsin and rod-cone photoreceptors to the pupillary light reflex in humans, we compared pupillary light responses in normally-sighted individuals (n = 24) with a blind individual lacking rod-cone function. Here, we show that visual photoreceptors are required for normal pupillary responses to continuous light exposure at low irradiance levels, and for sustained pupillary constriction during exposure to light in the long-wavelength portion of the visual spectrum. In the absence of rod-cone function, pupillomotor responses are slow and sustained, and cannot track intermittent light stimuli, suggesting that rods/cones are required for encoding fast modulations in light intensity. In sighted individuals, pupillary constriction decreased monotonically for at least 30 minutes during exposure to continuous low-irradiance light, indicating that steady-state pupillary responses are an order of magnitude slower than previously reported. Exposure to low-irradiance intermittent green light (543 nm; 0.1–4 Hz) for 30 min, which was given to activate cone photoreceptors repeatedly, elicited sustained pupillary constriction responses that were more than twice as great compared to exposure to continuous green light. Our findings demonstrate non-redundant roles for rod-cone photoreceptors and melanopsin in mediating pupillary responses to continuous light. Moreover, our results suggest that it might be possible to enhance non-visual light responses to low-irradiance exposures by using intermittent light to activate cone photoreceptors repeatedly in humans.