The temporal resolution of binaural integration in the lateral superior olive and its implications for the electrical restoration of spatial hearing

突触输入的精确时间整合是神经元回路中感觉处理的基本原理之一。特别是，在听觉系统中，脑干中的神经元检测到兴奋性和抑制性输入之间到达时间的差异仅在微秒的范围内，从而允许对声源进行准确定位。这种能力对于人类的交流（例如在嘈杂的环境中进行对话，例如在聚会上）和导航（例如穿过繁忙的道路）都是必不可少的。尽管我们在日常生活中经常执行这些任务，但潜在的神经元机制，特别是这种双耳整合的时间限制和抑制性输入的作用，仍然没有完全理解。然而，无论是对快速神经元整合机制的基本理解，还是从临床角度来看，由于声音定位的恢复仍然是人工耳蜗（CIs）的主要障碍之一，因此对听觉处理的这些方面的全面了解都是非常必要的。利用我们在哺乳动物听觉脑干生理学及其系统发育方面的丰富专业知识，我们旨在研究抑制在神经元声音定位加工中的作用，特别是抑制的时间精度范围。利用一种概念新颖的方法，我们将在蒙古沙鼠（Meriones unguiculatus）中进行体内电生理记录，以表征双耳整合神经元及其单耳输入核的突触输入的功能分辨率。在声学（即自然）刺激的同时，我们将获得利用耳蜗电刺激的补充数据集。这不仅可以让我们评估涉及突触抑制的双耳整合的时间分辨率，还可以确定电刺激过程中快速信息处理的基本原理，最终将有助于CI用户声音定位的生理恢复。

The precise temporal integration of synaptic inputs represents one of the fundamental principles of sensory processing in neuronal circuits. Particularly, in the auditory system, neurons in the brainstem detect differences in the arrival time between excitatory and inhibitory inputs on the scale of only microseconds to allow for the accurate localization of a sound source. This ability is essential both for human communication (e.g. attending to a conversation in a noisy environment such as a party) as well as navigation (e.g. crossing a busy road). Whereas we routinely perform these tasks in everyday life, the underlying neuronal mechanisms, particularly the temporal limits of this binaural integration and the role of inhibitory inputs, are still not fully understood. Yet a comprehensive knowledge about these aspects of auditory processing is highly desirable , both for the basic understanding of fast neuronal integration mechanisms and from a clinical perspective, as the restoration of sound localization remains one of the central obstacles of cochlear implants (CIs). Taking advantage of our rich expertise on mammalian auditory brainstem physiology and its phylogeny, we aim to investigate the role of inhibition in neuronal sound location processing, particularly the bounds of temporal precision of inhibition. Utilizing a conceptually novel approach, we will perform in vivo electrophysiological recordings in Mongolian Gerbils (Meriones unguiculatus) to characterize the functional resolution of synaptic inputs both in binaural integration neurons as well as their monaural input nuclei. In parallel to acoustic (i.e. naturalistic) stimulation, we will obtain a complementary data set employing electrical stimulation of the cochleae. This will not only allow us to assess the temporal resolution of binaural integration involving synaptic inhibition, but also to identify basic principles of fast information processing during electrical stimulation, which ultimately will contribute towards the physiological restoration of sound localization in CI users.