LOW RETINAL NOISE IN ANIMALS WITH LOW BODY-TEMPERATURE ALLOWS HIGH VISUAL SENSITIVITY
LOW RETINAL NOISE IN ANIMALS WITH LOW BODY-TEMPERATURE ALLOWS HIGH VISUAL SENSITIVITY
复制标题
DOI：
10.1038/334348a0
复制
发表时间：
1988-07-28
期刊：
影响因子：
64.8
通讯作者：
REUTER, T
中科院分区：
文献类型：
--
作者：
AHO, AC;DONNER, K;REUTER, T
人类可以检测到的最弱的光脉冲通过瞳孔发送大约100个光子，并在一个小的视网膜区域中产生10-20个视紫红质异构化。我们不能看到单个光子，这是因为随机发生的热异构化产生了视网膜噪声。直接记录已经证明了存在的电'暗'杆事件与光异构化信号4 -6。它们的平均发生率大致与心理物理阈值实验中的“暗光”一致，它们的热参数证明了热异构化的识别。在两栖动物的视网膜中，一小部分敏感的神经节细胞具有性能限制噪声，该噪声足够低，可以很好地解释这些事件7 -10。在这里，我们研究的性能黑暗适应蟾蜍和青蛙，并表明，视觉引导行为的性能极限也设置热异构化。由于受热事件限制的视觉灵敏度在温度福尔斯下降时会上升，因此生活在低温下的变温脊椎动物应该达到哺乳动物和鸟类在光学因子相等的情况下无法达到的光敏感度。不同物种在不同温度下的比较显示了视网膜中的绝对阈值强度和估计的热异构化率之间的相关性。
The weakest pulse of light a human can detect sends about 100 photons through the pupil and produces 10–20 rhodopsin isomerizations in a small retinal area1,2. It has been postulated3that we cannot see single photons because of a retinal noise arising from randomly occurring thermal isomerizations. Direct recordings have since demonstrated the existence of electrical 'dark' rod events indistinguishable from photoisomerization signals4–6. Their mean rate of occurrence is roughly consistent with the 'dark light' in psychophysical threshold experiments, and their thermal parameters justify an identification with thermal isomerizations5. In the retina of amphibians, a small proportion of sensitive ganglion cells have a performance-limiting noise that is low enough to be well accounted for by these events7–10. Here we study the performance of dark-adapted toads and frogs and show that the performance limit of visually guided behaviour is also set by thermal isomerizations. As visual sensitivity limited by thermal events should rise when the temperature falls, poikilothermous vertebrates living at low temperatures should then reach light sensitivities unattainable by mammals and birds with optical factors equal. Comparison of different species at different temperatures shows a correlation between absolute threshold intensities and estimated thermal isomerization rates in the retina.