Neuroethology of navigation in Tritonia

我的总体目标是了解动物如何使用多种导航策略来移动。我和我的学生将通过关注海蛞蝓Tritonia diomedea的气味导航来解决这个问题。人们花了相当大的努力来了解动物如何对有吸引力的气味羽状物做出反应，从而找到气味的来源。各种各样的研究表明，蛞蝓和其他动物并不仅仅利用气味来完成这个过程。相反，气味的存在会刺激动物向上游爬行，跟随气味的流向。然而，在自然界中，流动方向经常改变。我们对水流变化对动物导航的影响知之甚少。我的前两个目标是探索鼻涕虫如何在两个不同的水平上应对流动变化：一个水平应该被跟踪，以便到达气味源，另一个水平应该被忽略，以成功导航。首先，随着栖息地内气流方向的改变，气味羽流也会随之改变。动物必须追踪携带气味羽流的气流的变化，以找到气味的来源。我和我的学生将使用现场录像来探索Tritonia对不同程度的流动流动的反应。其次，在由不变的散装气流携带的气味羽流中，海底的水运动在流动方向上产生较小的变化。这种湍流不能为寻找气味来源提供有用的信息，应该忽略。蛞蝓的运动表明它们可能适应了湍流，但这种可能性还没有实验证实。因此，我还将测试段塞对更细微的流动变化的反应，从而深入了解段塞如何区分整体流动方向的变化和湍流的变化。我的最终目标是为探索蛞蝓的神经系统是如何产生这些行为奠定基础。Tritonia的实验适应性和更简单的神经系统允许实验测试单个神经元在线索检测和随后的控制机制中的作用。我建议研究神经系统感觉成分的结构和功能，以及测试哪些神经元直接控制流动中气味刺激的转向。这两个组成部分分别作为控制导航的神经元回路的输入和输出，其结果将指导未来研究该回路如何产生不同导航策略的工作。更一般地说，通过将这些结果与动物王国的结果进行比较，我们可以对导航行为背后的神经机制有更广泛的了解。此外，这里使用的方法适用于神经科学的其他领域，我的学生在继续从事学术或职业生涯时将获得宝贵的技能。

My overall goal is to understand how animals use multiple navigation strategies to move.  My students and I will tackle this problem by focusing on odour-based navigation in the sea slug Tritonia diomedea. Considerable effort has been spent understanding how animals respond to attractive odour plumes to find odour sources.  A variety of studies have shown that the slugs and other animals do no use odours alone for this process.  Instead, the presence of odours stimulate the animals to crawl upstream, following the flow to the odour source. Yet, in nature, flow directions frequently change. We know much less about the consequences of this flow variability on animal navigation. My first two objectives are to explore how the slugs cope with flow variability at two different levels: one level that should be tracked in order to reach the odour source, and another level that should probably be ignored for successful navigation. First, as bulk flow direction changes in a habitat, so too do odour plumes.   Animals must track these changes in the flow carrying the odour plume to find odour sources. My students and I will use field video recordings to explore how responsive Tritonia is to shifting flows of varying degrees. Second, inside an odour plume carried by unchanging bulk flow, water movement across the sea floor generates smaller scale variations in flow direction. This turbulence does not provide useful information for finding the odour source, and should be ignored.  The slugs show movements that suggest they may be adapted to cope with the turbulence, but there has been no experimental verification of this possibility.  Consequently, I will also test for how responsive the slugs are to finer flow variations, and thus gain insight into how the slugs may differentiate between changes in bulk flow direction versus changes from turbulent flow. My final objective is to lay a foundation for exploration of how the slugs’ nervous system produces these behaviours. The experimental amenability and simpler nervous system of Tritonia allow experiments to test the roles of single neurons in cue detection and the subsequent control mechanisms of the slugs’ crawling. I propose to study the structure and function of the sensory components of the nervous system, as well as test which neurons directly control turns stimulated by odours in flow. These two components serve as the input and output respectively for the circuit of neurons that controls navigation, and the results will guide future work studying how that circuit functions to produce the different navigational strategies. More generally, by comparing these results to those from across the animal kingdom, we can achieve a broader understanding of the neural mechanisms underlying navigation behaviour. Moreover, the methods used here are applicable to other areas of neuroscience, and my students will acquire valuable skills as they continue in academic or professional careers.