A "Melanopic" Spectral Efficiency Function Predicts the Sensitivity of Melanopsin Photoreceptors to Polychromatic Lights
A "Melanopic" Spectral Efficiency Function Predicts the Sensitivity of Melanopsin Photoreceptors to Polychromatic Lights
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DOI：
10.1177/0748730411409719
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发表时间：
2011-08-01
影响因子：
3.5
通讯作者：
Lucas, Robert
中科院分区：
文献类型：
--
作者：
al Enezi, Jazi;Revell, Victoria;Lucas, Robert
哺乳动物视网膜中的光感受不限于视杆细胞和视锥细胞，而是延伸到少数表达黑视素的固有光敏视网膜神经节细胞。这些mRGC对昼夜节律诱导、瞳孔光反射和其他所谓的非成像（NIF）反应尤其重要。通过比较对一系列单色刺激的反应，已经在几个物种中解决了黑视素光转导的光谱敏感性。所得的作用光谱与基于视蛋白：维生素A的色素的预测曲线（列线图）匹配，峰值灵敏度（λ（max））在480 nm左右。最有用的是能够使用该光谱敏感度函数来预测黑视蛋白对广谱（包括“白色”光）的敏感度。然而，黑视素是一种具有内在光依赖性漂白恢复机制的色素，这一证据提出了光谱质量和感光器响应之间更复杂关系的可能性。在这里，我们开始凭经验确定是否简单地加权光功率在每个波长根据480 nm诺模图和整合整个光谱可以预测黑视蛋白的敏感性，各种多色刺激。我们表明，瞳孔和昼夜节律的反应，小鼠完全依赖于黑视蛋白的光敏性（rd/rd cl）确实可以准确地预测使用这种方法。因此，我们的数据表明，480 nm诺模图可以作为一个新的光度测量的光强度（我们称之为“melanopic”）相关的黑视蛋白光感受的基础。他们进一步表明，以这些术语测量光预测黑视素对发散光谱组成的光的响应比目前广泛使用的用于量化辐照度或照度的其他方法可靠得多。
Photoreception in the mammalian retina is not restricted to rods and cones but extends to a small number of intrinsically photosensitive retinal ganglion cells expressing the photopigment melanopsin. These mRGCs are especially important contributors to circadian entrainment, the pupil light reflex, and other so-called nonimage-forming (NIF) responses. The spectral sensitivity of melanopsin phototransduction has been addressed in several species by comparing responses to a range of monochromatic stimuli. The resultant action spectra match the predicted profile of an opsin: vitamin A-based photopigment (nomogram) with a peak sensitivity (lambda(max)) around 480 nm. It would be most useful to be able to use this spectral sensitivity function to predict melanopsin's sensitivity to broad-spectrum, including "white," lights. However, evidence that melanopsin is a bistable pigment with an intrinsic light-dependent bleach recovery mechanism raises the possibility of a more complex relationship between spectral quality and photoreceptor response. Here, we set out to empirically determine whether simply weighting optical power at each wavelength according to the 480-nm nomogram and integrating across the spectrum could predict melanopsin sensitivity to a variety of polychromatic stimuli. We show that pupillomotor and circadian responses of mice relying solely on melanopsin for their photosensitivity (rd/rd cl) can indeed be accurately predicted using this methodology. Our data therefore suggest that the 480-nm nomogram may be employed as the basis for a new photometric measure of light intensity (which we term "melanopic") relevant for melanopsin photoreception. They further show that measuring light in these terms predicts the melanopsin response to light of divergent spectral composition much more reliably than other methods for quantifying irradiance or illuminance currently in widespread use.