Colour and polarization visual pathways of the northern anchovy: from neuroethology to machine sensor technology

除了波长（颜色）和强度（光子数量）外，许多无脊椎动物还可以探测光的偏振，并将其用于各种目的，包括定向、猎物探测、捕食者躲避和交流。光的偏振是指构成它的光子的电场振荡的主要平面。如果所有光子的电场在同一平面上振荡，光在该平面上被称为100%线偏振（e向量平面）。在脊椎动物中，偏振视觉，包括解释偏振检测的细胞机制，仅在某些种类的凤尾鱼中建立。在这些动物中，一组视网膜锥状光感受器是轴向二向性的，也就是说，它们对进入眼睛的入射光的偏振（e矢量方向）敏感。这是因为，与迄今为止研究过的其他脊椎动物的锥体不同，这些轴向二向性的锥体有平行于细胞长度的片层。两个这样的视锥细胞（短的和长的）具有相互垂直的片层，形成两个具有正交偏振灵敏度的视网膜通道的输入。我最近展示了北凤尾鱼（Engraulis mordax）的腹侧视网膜，该视网膜被划分为颜色和偏振敏感度，这是脊椎动物中首次发现这类视网膜。腹颞视网膜具有轴向二色性视锥细胞，介导偏振，但在视神经水平上不具有颜色敏感性，而腹鼻视网膜具有三重视锥细胞（与其他脊椎动物一样，片层横向与光感受器的长度相同），对偏振不敏感，但对颜色敏感。这种视觉模式的功能分离只在复眼的一个专门区域处理偏振信息，而眼睛的其余部分致力于色觉的昆虫中才知道。组成凤尾鱼的颜色和偏振视觉通路的细胞的特性是未知的。利用分子（qPCR，原位杂交），电生理（细胞内/膜片钳）和数学建模技术的组合，本研究将试图揭示构成北凤尾鱼颜色和极化视觉通路的细胞特性。为了了解动物在自然界中对偏振视觉的使用，我们将进行行为学研究，以验证偏振敏感性增强凤尾鱼对浮游动物的目标对比度感知，从而提高其觅食性能的假设。最后，本研究将优化受凤尾鱼眼睛光学结构启发的新型偏振传感器。这些传感器远远优于市场上现有的传感器，并可能通过在相机和手机等设备上的大规模应用，彻底改变整个行业。

In addition to wavelength (colour) and intensity (number of photons), many invertebrates can detect the polarization of light and use it for a variety of purposes including orientation, prey detection, predator avoidance, and communication. The polarization of light refers to the predominant plane of electric field oscillations of the photons that comprise it. If all the photons have electric fields that oscillate in the same plane, light is termed 100% linearly polarized in that plane (the E-vector plane). In vertebrates, polarization vision, including a cellular mechanism explaining polarization detection, has only been established for some species of anchovies. In these animals, a set of retinal cone photoreceptors are axially dichroic, i.e., they are sensitive to the polarization (E-vector orientation) of incident light that enters the eye. This is due to the fact that, unlike the cones in other vertebrates examined so far, these axially dichroic cones have lamellae oriented parallel to the length of the cell. Two such cones (short and long) have lamellae that are perpendicular to each other forming the inputs to two retinal channels with orthogonal polarization sensitivity. I have recently shown that the northern anchovy, Engraulis mordax, has a ventral retina that is compartmentalized for colour and polarization sensitivity, the first discovery of its kind among vertebrates. The ventro-temporal retina has axially dichroic cones that mediate polarization but not colour sensitivity at the level of the optic nerve, whereas the ventro-nasal retina has triple cones (with lamellae transverse to the photoreceptor's length, as in other vertebrates) and is not polarization-sensitive but colour-sensitive. Such functional segregation of visual modalities is only known in insects where a specialized area of the compound eye processes polarization information whereas the rest of the eye is devoted to colour vision. The properties of cells that make up the colour and polarization visual pathways of anchovies are unknown. Using a combination of molecular (qPCR, in-situ hybridization), electrophysiological (intracellular/patch clamp), and mathematical modeling techniques, this research will attempt to unveil the properties of cells that underlie the colour and polarization visual pathways of the northern anchovy. To understand the animal's use of polarization vision in nature, behavioural studies will be carried out to test the hypothesis that polarization sensitivity enhances target contrast perception of zooplankton by the anchovy, thereby improving its foraging performance. Lastly, this research will optimize novel polarization sensors inspired by optical structures found in the eyes of anchovies. These sensors are far superior to those presently found in the market place and could revolutionize the industry through mass applications in devices like cameras and cell phones.