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)之外，许多无脊椎动物还可以检测光的偏振，并将其用于各种目的，包括定位、检测猎物、躲避捕食者和通信。光的偏振是指构成光的光子的电场振荡的主要平面。如果所有的光子都具有在同一平面内振荡的电场，则光在该平面(E矢量平面)中被称为100%线偏振。在脊椎动物中，极化视觉，包括解释极化检测的细胞机制，只在某些种类的凤尾鱼中建立。在这些动物中，一组视网膜视锥感光细胞是轴向二色性的，即它们对进入眼睛的入射光的偏振(E向方向)很敏感。这是因为，与目前所研究的其他脊椎动物的锥体不同，这些轴向二向色性锥体具有平行于细胞长度的片层。两个这样的视锥(短的和长的)都有彼此垂直的薄片，形成了两个具有正交偏振敏感性的视网膜通道的输入。*我最近发现，北方凤尾鱼Engraulis mordax的腹侧视网膜根据颜色和偏振敏感性进行划分，这在脊椎动物中是首次发现。腹-颞侧视网膜有轴向二向色锥，在视神经水平上调节偏振，但不对颜色敏感，而腹-鼻侧视网膜有三个锥体(像其他脊椎动物一样，有横跨感光细胞长度的片层)，不是偏振敏感的，而是颜色敏感的。这种视觉形态的功能分离只在昆虫中已知，在昆虫中，复眼的一个专门区域处理偏振信息，而眼睛的其余部分则致力于颜色视觉。构成凤尾鱼颜色和偏振视觉通路的细胞的特性尚不清楚。这项研究结合了分子(qPCR，原位杂交)、电生理学(细胞内/膜片钳)和数学建模技术，试图揭示构成北部凤尾鱼颜色和偏振视觉通路的细胞特性。为了了解动物在自然界中使用偏振视觉的情况，将进行行为研究，以测试偏振敏感性增强凤尾鱼对浮游动物的目标对比度感知，从而改善其觅食性能的假设。最后，这项研究将优化新型偏振传感器，灵感来自凤尾鱼眼睛中发现的光学结构。这些传感器远远优于目前市场上找到的传感器，并可能通过在相机和手机等设备上的大规模应用来彻底改变该行业。

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.