Interaction of optic flow and sky compass signals in the central complex of the desert locust Schistocerca gregaria

像脊椎动物一样的昆虫在空间定位和导航方面表现出复杂的能力。这包括超过数千公里的季节性迁徙和中心觅食者的归巢行为。除了用于确定导航方向的地标和天空罗盘方向外，昆虫还使用步数机制（在行走过程中）或依赖于光流的机制来估计距离。来自不同物种的神经生物学数据越来越多地指向中枢复合体在各种导航任务中的关键作用。在果蝇中，中央复合体在空间记忆、方向决定以及空间中身体方向的编码中发挥作用。我们在沙漠蝗虫研究小组的工作中发现，在中心复合体中有一个中间神经元网络，它可以编码相对于天空罗盘信号的空间方向，特别是蓝天的偏振模式。相比之下，中枢神经对距离信息的监测和整合在很大程度上是不清楚的。在这个项目中，我们希望通过表征和识别神经元来弥补这一差距，这些神经元对视觉流场做出特定的反应，从而对飞行中距离估计相关的信号做出反应。该项目将揭示哪些神经元对光流敏感，以及这些信号如何与天空罗盘信息相结合。在该项目的第二部分，gaba能和酪胺能信号传输的作用将被解决。我们将测试gaba能神经元向中枢复合体提供天空罗盘信息的假设，而酪胺能神经元提供光流输入。通过药理学操作，将研究这两种递质在中枢复合体神经元生理学中的作用，以及GABA在极化趋向性行为中的作用。该研究可能揭示昆虫空间定向中枢神经控制的重要方面，并将为空间控制的计算模型奠定基础。

Insects like vertebrates show sophisticated performance in spatial orientation and navigation. This includes seasonal migrations over thousands of kilometers and homing behavior in central-place foragers. Besides landmark- and sky compass orientation for determining navigational directions, a step counting mechanism (during walking) or an optic flow dependent mechanism is used by insects for distance estimation. Neurobiological data from various species increasingly point to a key role of the central complex in diverse navigational tasks. In the fly Drosophila the central complex plays a role in spatial memory, in directional decisions as well as in the coding of body orientation in space. Work from our own group in desert locusts have discovered a network of interneurons in the central complex, which encodes spatial orientations relative to sky compass signals, in particular the polarization pattern of the blue sky. In contrast, the central nervous monitoring and integration of distance information is largely unclear. In this project we want to bridge this gap by characterizing and indentifying neurons that respond specifically to visual flow fields and thus respond to signals that are relevant for distance estimation in flight. The project shall uncover, which neurons are optic-flow sensitive and how these signals are integrated with sky compass information. In a second part of the project, the role of GABAergic and tyraminergic signal transmission will be addressed. We will test the hypothesis that GABAergic neurons provide sky compass information to the central complex, whereas tyraminergic neurons provide optic flow input. Through pharmacological manipulation, the role of both transmitters will be studied on the physiology of central-complex neurons, and the role of GABA on polarotaxis behaviour. The proposed research is likely to uncover important aspects of central nervous control of spatial orientation in insects and will be a basis for computational models of spatial control.