Comparative Investigations of neuronal integration processes along the auditory pathway in simple systems

我们的世界充满了可以被感觉器官检测到并被大脑评估的物理刺激。为了繁殖或生存，声波的检测对许多动物来说是必不可少的。沿着听觉通路的沿着神经元通过耳朵的传入纤维的突触输入而被告知周围的声音。在简单的听觉系统中，只有沿着通往大脑的听觉通路的低突触水平，例如在蟋蟀中，前胸神经节的输入是第一个重要的信号整合中心。在这个水平上的神经元反应是基于初级感觉神经元的尖峰，初级感觉神经元编码声音的频谱和时间信息。虽然在耳朵中的频率歧视，这是由音调行波，是很好地理解蟋蟀，时间编码的动态仍在调查中，目前的建议的一个焦点。在这项比较研究中，我们将调查两个不同的蟋蟀物种的神经元整合。这两个物种在交配行为上表现出性别特异性差异，如趋声性和它们的耳朵具有显着不同的形态。在一个物种中，Ancylecha fenestrata，听觉器官被广泛扩展，并提供了一个过度的行为重要的听觉输入，一个听觉中心凹。总共约有110个轴突投射到前胸神经节。这里分析的另一个物种，Mecopoda elongata，只有大约45个轴突向前胸神经节发送投射，没有任何过度表现。我们的比较研究将调查在两个物种的神经元整合过程，旨在获得知识的优势，建立一个听凹。在这个项目中，我们使用多电极和细胞内记录在前胸神经节的局部场电位在一个小的网络，这是由声音引起的信号从蟋蟀耳朵，这反过来又是由激光多普勒振动测量，细胞内记录和神经解剖学研究调查的神经元整合。

Our world is full of physical stimuli that can be detected by sensory organs and evaluated by the brain. For reproduction or survival, the detection of sound waves is essential for many animals. Neurons along the auditory pathway are informed about surrounding sounds by synaptic inputs through afferent fibres of the ear. In simple hearing systems with only low synapse levels along the auditory pathway to the brain, such as in bushcrickets, the input to prothoracic ganglion is the first important signal integration centre. The neuronal response at this level is based on the spiking of primary sensory neurons that encode spectral as well as temporal information of the sound. While frequency discrimination in the ear, which is accomplished by tonotopical travelling waves, is well understood in bushcrickets, the dynamics of the temporal encoding is still under investigation and one focus of the current proposal. In this comparative study we will investigate the neuronal integration in two different bushcricket species. Both species show sex-specific differences in mating behavior, like phonotaxis and their ears feature significantly different morphologies. In one species, Ancylecha fenestrata, the hearing organ is extensively expanded and provides an overrepresentation of behaviorally important auditory input, an auditory fovea. In total about 110 axons project to the prothoracic ganglion. The other here analyzed species, Mecopoda elongata, has only about 45 axons sending projections to the prothoracic ganglion without any overrepresentation. Our comparative study will investigate the neuronal integration process in both species and aims to gain knowledge on the advantage to build up an auditory fovea. In this project we use multielectrode and intracellular recordings in the prothoracic ganglion to investigate the neuronal integration by local field potentials in a small network, which is determined by the sound-induced signals from the bushcrickets ear, which in turn are investigated by Laser Doppler Vibrometry, intracellular recordings and neuroanatomical studies.