Motor control of auditory steering in crickets

神经科学在了解神经元和神经元网络的功能方面取得了巨大的进步。对运动系统或感觉通路的分析揭示了动物如何从环境中产生运动模式或处理感觉信息的基本原理。然而，感觉-运动接口，即中枢神经系统的网络，在那里处理感觉信号和产生适当的运动命令，很少被研究，因为重点要么是运动系统，要么是感觉系统。该项目的目的是考虑这两个方面，并分析雌性蟋蟀听觉诱发转向反应背后的运动活动。这些动物以雄鸟的叫声为定位，朝向鸣叫的雄鸟。在神经生物学中，它们是多年来用于分析听觉处理的神经机制的模型系统。板球听觉通路的神经元得到了很好的描述，我们对动物在神经系统早期如何处理声音模式有了很好的了解。然而，我们仍然缺乏关键信息，即它们是如何识别雄鸟的叫声的，以及它们是如何设法转向歌声伙伴的。在以前的许多实验中，一般都是对受制动物的听觉处理进行分析。在这些实验中，没有迹象表明是否识别了感觉信号并产生了适当的运动指令。在我们的实验中，被拴住的蟋蟀将在轨迹球上行走，并将朝着一个健全的模式前进。因此，该项目将通过监测动物的行走行为来克服以前方法的一个基本实验问题。这将是一个可靠的指标，表明趋音性被激发，并且对听觉信号的相应处理已经开始。这对于我们展示和理解听觉到运动通路背后的神经机制至关重要。与行走行为一起，我们将记录特定运动神经元和中间神经元的活动，它们控制着前腿的转向运动。这些实验将告诉我们，为了控制转向动作，大脑向运动神经元发送了哪种类型的听觉诱发命令。他们还将演示听觉模式识别过程如何将听觉中间神经元的反应转换为控制腿部运动的运动命令。分析这个模型系统将揭示听觉处理的原理，并将有助于行为神经科学的一个关键目标，即从感觉处理到运动模式生成，理解动物行为的神经组织。

Neuroscience has made enormous progress in understanding the function of neurons and neuronal networks. The analysis of motor systems or sensory pathways has revealed fundamental principles of how animals generate motor patterns or process sensory information from their environment. However, sensory-to-motor interfaces, the networks of the central nervous system where sensory signals are processed and appropriate motor commands are generated, have rarely been studied, as the focus is either on motor systems or on sensory systems. The aim of the project is to consider both aspects and to analyse the motor activity underlying auditory evoked steering responses in female crickets. These animals orient towards singing males using the male's calling song for orientation. In neurobiology they are model systems for analysing the neural mechanisms of auditory processing since many years. The neurons of the cricket auditory pathway are well described and we have a very good understanding, how the animals process sound patterns at the early stages of their nervous system. However, we still lack the crucial information, how they actually recognise the calling songs of the males and how they then manage to steer towards the singing mate. In many previous experiments auditory processing was generally analysed in restrained animals. In those experiments there was no indication, if the sensory signals were recognised and appropriate motor commands were generated. In our experiments tethered crickets will be walking on a trackball and will steer towards a sound pattern. The project will therefore overcome a fundamental experimental problem of previous approaches by monitoring the walking behaviour of the animals. This will be a reliable indicator that phonotaxis is elicited and that the corresponding processing of auditory signals has been initiated. This is crucial for our approach to demonstrate and understand the neural mechanisms underlying the auditory-to-motor pathway. Together with the walking behaviour we will record the activity of specific motoneurons, and interneurons, which control the steering movements of the front legs. These experiments will tell us, what type of auditory evoked commands are send to the motoneurons from the brain, in order to control the steering movements. They will also demonstrate how an auditory pattern recognition process, transforms responses of auditory interneurons into motor commands controlling leg movements. Analysing this model system will reveal principles of auditory processing and will contribute to a pivotal aim of behavioural neuroscience that is to understand the neural organisation of animal behaviour from sensory processing to motor pattern generation.