Neuronal processing of sky compass information in the brain of bees

许多动物拥有一个时间补偿的太阳罗盘，这使他们能够推断出一个固定的地球方向，例如。到一个巢穴，从不断变化的太阳方位角。太阳光在大气中的散射导致了天空中颜色的梯度和偏振光的沿着分布。这两种现象在空间上都与太阳方位角直接相关。除了直接看到太阳之外，它们还可以用来推断太阳方位角。六十多年来，蜜蜂一直被用作行为实验中天空罗盘定位的模型生物。 然而，这种迷人行为背后的神经元基础至今仍是个谜。本研究的目的是利用神经生理学技术来阐明蜜蜂大脑中与导航相关的偏振和彩色视觉线索的处理过程。由于大量的行为数据，它们相当简单的大脑（与脊椎动物相比），以及将这些动物保持在户外的独特可能性，即在自然光条件下，蜜蜂不像其他物种那样适合这些实验。两个问题构成了这一建议的核心。1.偏振光和非偏振光刺激如何整合到这些动物的大脑中？2.天空罗盘系统的动态特性（昼夜节律和毫秒时间尺度）是什么？在天空指南针导航过程中，大脑必须解决一项高度复杂的任务。一方面，必须整合关于太阳方位角的所有可用信息（偏振光刺激的取向、非偏振光刺激的方位角和颜色）。另一方面，动物必须能够区分太阳，天空和云在任何时候。例如，当太阳本身不可见时，被阳光照射的云不应该被错误地解释为太阳。通过用不同偏振光和非偏振光刺激的刺激，将使用细胞内记录来阐明潜在的机制。在项目的第二部分，将研究天空罗盘系统神经元的长期和短期变化。钙成像和细胞外记录将用于监测昼夜变化和神经活性物质对这些的影响。使用细胞内记录将使我能够研究神经元调谐的短期变化，这些变化是通过动态视觉刺激引起的，就像在飞行过程中所经历的那样。这个项目的结果将提供深入了解导航相关的视觉刺激的感觉处理的基本神经元的原则。

Many animals possess a time-compensated sun compass, which enables them to infer a fixed earthbound direction, eg. to a nest, from the continually changing solar azimuth. Scattering of sun light in the atmosphere leads to a color gradient and a pattern of polarized light along the sky. Both phenomena are spatially directly linked to the solar azimuth. In addition to the direct view of the sun, they can therefore be exploited to infer the solar azimuth. For more than six decades, bees have been used as model organisms for sky compass orientation in behavioral experiments. However, the neuronal basis underlying this fascinating behavior has so far remained enigmatic. The goal of this project is to elucidate the processing of navigationally relevant polarized and chromatic visual cues in the brain of bees, using neurophysiological techniques. Due to the abundance of behavioral data available, their rather simple brain (compared to vertebrates), and the unique possibility to keep these animals outdoors, i.e. under natural light conditions, bees lend themselves to these experiments like no other species. Two questions form the core of this proposal. 1. How are polarized and unpolarized light stimuli integrated in the brain of these animals? 2. What are the dynamic properties (both circadian and on the ms-s timescale) of the sky compass system? During sky compass navigation, the brain has to solve a highly sophisticated task. On one hand, all available pieces of information regarding solar azimuth have to be integrated (orientation of polarized light stimuli, azimuth and color of unpolarized light stimuli). On the other hand the animal has to be able to differentiate between sun, sky, and clouds at all times. For example when the sun itself is not visible a sunlit cloud should not be erroneously interpreted as the sun. By stimulation with different polarized and unpolarized light stimuli the underlying mechanisms will be elucidated using intracellular recordings. In the second part of the project, long- and short-term changes of neurons of the sky compass system will be investigated. Calcium imaging and extracellular recordings will be used to monitor diurnal changes and the influence of neuroactive substances on these. Using intracellular recordings will allow me to investigate short-term changes in neuronal tuning that are elicited through dynamic visual stimuli, as experienced during flight. The outcome of this project will provide insight into fundamental neuronal principles underlying sensory processing of navigationally relevant visual stimuli.