Uncovering the Role of GIT Proteins in Encoding Acoustic Information.

世界的听觉感知依赖于声压波转化为神经元之间时间上精确和快速的动作电位（AP）信号。声源的定位是双耳感知的基础，以定位空间中的物体（例如，接近的汽车），并且对于理解噪声中的语音至关重要。与视觉或躯体感觉系统中的空间信息在感觉上皮水平上表示不同，声源的位置必须通过大脑中的神经元计算来重建。这些神经元计算需要哺乳动物神经系统中最高的时间分辨率。然而，神经元通讯依赖于突触前末梢有限数量的突触囊泡（SV）释放神经递质。SV释放的动力学决定了AP信号传导的时机和功效。要了解时间精确和有效的AP生成是如何建立的，关键是要确定哪些分子机制控制SV的动态突触前终端。双耳声音处理的第一阶段的关键突触是位于听觉脑干中的Held/MNTB突触的萼。Held/MNTB突触的花萼在高达数百赫兹的放电频率下具有非凡的突触传递保真度和可靠性。最近的研究表明，G蛋白偶联受体激酶相互作用蛋白（GITs）通过调节SV释放概率来控制突触强度。然而，GIT蛋白在实现时间上精确和持续的听觉信号传导中的作用是未知的。分子，细胞，以及行为方法的组合将被用来产生新的见解的分子机制，所需的编码声学信息。首先，GIT蛋白质将选择性地消融在萼举行的结合新的病毒载体技术与转基因小鼠系规避胚胎致死的常规敲除动物。将在急性脑切片中进行全细胞膜片钳记录，以测量GIT蛋白对SV动力学的影响。为了模拟冲击神经系统的环境，所有实验将在接近生理条件下对功能完全发育的突触进行。将在模拟神经元对自然声音（如语音）的反应的刺激条件下评估确保精确和可靠的AP放电的能力。最后，将使用被动行为范例测试在GIT蛋白缺失后定位声音的能力。该项目预计将产生新的见解GIT蛋白在调节SV动力学的分子机制及其在编码声学信息中的作用。

The auditory perception of the world relies on the transformation of sound pressure waves into temporally precise and rapid action potential (AP) signaling between neurons. The localization of a sound source is fundamental for binaural perception, to localize objects in space (e.g. approaching cars) and crucial for understanding speech in noise. Unlike in the visual or somatosensory system in which spatial information is represented at the level of the sensory epithelium, the location of a sound source has to be reconstructed by neuronal computations in the brain. These neuronal computations require the highest temporal resolution in the mammalian nervous system. Neuronal communication, however, relies on the release of neurotransmitters from a limited number of synaptic vesicles (SV) from the presynaptic terminal. The dynamics of SV release critically determine the timing and efficacy of AP signaling. To understand how temporal precise and efficient AP generation is established it is crucial to identify which molecular mechanisms control SV dynamics in the presynaptic terminal. A critical synapse for the first stages of binaural sound processing is the calyx of Held/MNTB synapse located in the auditory brainstem. The calyx of Held/MNTB synapse has extraordinary fidelity and reliability of synaptic transmission up to hundreds of Hertz firing rate. Recently, it was shown, that G protein-coupled receptor kinase-interacting proteins (GITs) control synaptic strength by regulation SV release probability. However, the GIT proteins’ role in enabling temporally precise and sustained auditory signaling is unknown. A combination of molecular, cellular, as well as behavioral methods will be used to generate novel insights into the molecular mechanisms that are required for encoding acoustic information. First, GIT proteins will be selectively ablated in the calyx of Held by combining novel viral vector technology with transgenic mouse lines circumventing the embryonal lethality of conventional knock-out animals. Whole-cell patch-clamp recordings will be performed in acute brain slices to measure the impact of GIT proteins on SV dynamics. To mimic the environment of an impact nervous system, all experiments will be performed at near-physiological conditions on functionally fully developed synapses. The ability to ensure precise and reliable AP firing will be assessed under stimulus conditions which mimic the neuronal response to natural sounds such as speech. Finally, the ability to localize sounds after deletion of GIT proteins will be tested using a passive behavioral paradigm. The project is expected to generate novel insights into the molecular mechanism of GIT proteins in regulating SV dynamics and their role in encoding acoustic information.