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 IC神经元的通路和许多基本特征都受到它们的抑制作用的深刻影响 投入。对IC的GABA能抑制的一个重要来源来自脑干回路，该回路由 斜方体内侧核(MNTB)和邻近的上橄榄旁核(SPON)。这个 该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回路提取和编码听觉刺激 中断，并且该电路的输出有助于IC中的时间处理。的目标 这个应用是：i)确定MNTB和SPON神经元如何整合它们的突触输入以产生 此电路的输出，以及ii)检查MNTB/SPON电路的传出投影对 IC神经元的反应特性。三个具体目标，每个目标都侧重于这条道路上的一个特定步骤 从MNTB到IC，都提出了自己的观点。 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，主要关注IC神经元检测音调间隙和同步的能力 它们对正弦调幅音调的反应。将使用双录制配置来 可逆地使Spon神经元失活，同时从其在IC中的突触后目标进行记录。 在目标2和目标3中，我们将进行体内记录研究，以阐明抑制和兴奋在 改变SPON和MNTB神经元对刺激间断的反应特性。一个多步骤的， 将采用序贯方案系统地阻断特定的神经递质系统，以便 作为一个整体，揭示他们对单个单位回答的个人贡献。全面刻画 将执行每个记录的单元格。 在紧密放置的声音或成分之间检测到刺激不连续的敏锐度 声音在言语知觉中起着重要的作用，而时间加工的缺陷与 语言障碍。因此，对MNTB/SPON回路在动物体内的功能有了更好的了解 模型将提高我们对人类语音理解的神经基础的了解。

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.