Motor control of auditory steering in crickets

点击翻译按钮获取中文摘要

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.