NEURONS AND CIRCUITS OF PERIOLIVARY NUCLEI

摘要 下丘（IC）是几乎所有上行和下行听觉整合的主要部位， 通路，IC神经元的许多基本特征都是由它们的抑制作用深刻地塑造的。 输入。GABA能抑制IC的一个重要来源来自脑干回路， 斜方体内侧核（MNTB）和邻近的上级橄榄旁核（SPON）。的 本研究计划的长期目标是阐明MNTB/SPON回路在听力中的功能作用。 我们的中心假设是，MNTB/SPON电路提取和编码听觉刺激 不连续性，并且该电路的输出有助于IC中的时间处理。的目标 该应用是i）确定MNTB和SPON神经元如何整合它们的突触输入以生成 该电路的输出，以及ii）检查MNTB/SPON电路的传出投射对 IC神经元的响应特性。三个具体目标，每一个都专注于路径上的一个特定步骤，沿着 从MNTB到IC，提出了。 具体目标1将直接检查MNTB/SPON电路对声音处理的影响 在中脑，主要集中在IC神经元的能力，以检测音调的差距，并同步 它们对正弦幅度调制音调的反应。双记录配置将用于 可逆地记录SPON神经元，同时记录IC中的突触后靶点。 在目标2和3中，我们将进行体内记录研究，以阐明抑制和兴奋在以下方面的作用： 塑造SPON和MNTB神经元对刺激不连续性的响应特性。一个多步骤， 将采用顺序方案来系统地阻断特定的神经递质系统， 揭示了他们对整体单一单元响应的贡献。综合表征 将执行每个记录的单元。 在紧密放置的声音或声音成分之间检测刺激不连续性的敏锐度 声音在言语感知中起着重要作用，时间处理的缺陷与 语言障碍因此，为了更好地了解动物MNTB/SPON回路的功能， 模型将推进我们对人类语音理解的神经基础的认识。

Abstract The inferior colliculus (IC) is a major site for integration of virtually all ascending and descending auditory pathways, and many fundamental characteristics of IC neurons are profoundly shaped by their inhibitory inputs. A significant source of GABAergic inhibition to the IC originates from a brainstem circuit formed by the medial nucleus of the trapezoid body (MNTB) and the nearby superior paraolivary nucleus (SPON). The long-term goal of this research program is to clarify the functional role of the MNTB/SPON circuit in hearing. Our central hypothesis is that the MNTB/SPON circuit extracts and encodes auditory stimulus discontinuities, and that the output of this circuit contributes to temporal processing in the IC. The objectives of this application are i) to determine how MNTB and SPON neurons integrate their synaptic inputs to generate the output of this circuit, and ii) to examine the impact of the MNTB/SPON circuit's efferent projection on response properties of IC neurons. Three Specific Aims, each focusing on a specific step along the pathway from the MNTB to the IC, are proposed. Specific Aim 1 will directly examine the influence exerted by the MNTB/SPON circuit on sound processing in the midbrain, focusing primarily on the ability of IC neurons to detect gaps in tones, and to synchronize their responses to sinusoidally amplitude modulated tones. A dual recording configuration will be used to reversibly inactivate SPON neurons, while simultaneously recording from their postsynaptic targets in the IC. In Aims 2 and 3, we will perform in-vivo recording studies to clarify the roles of inhibition and excitation in shaping the response properties of SPON and MNTB neurons to stimulus discontinuities. A multi-step, sequential protocol will be employed to systematically block specific neurotransmitter systems in order to reveal their individual contributions to single-unit responses as a whole. Comprehensive characterizations of each recorded cell will be performed. The acuity with which stimulus discontinuities are detected between closely placed sounds or components of sounds plays an important role in speech perception, and deficits in temporal processing are related to language impairment. Therefore, a better understanding of the function of the MNTB/SPON circuit in animal models will advance our knowledge of the neural basis for human speech comprehension.