FUNCTIONAL PATHWAYS OF THE COCHLEAR NUCLEUS

我们的长期目标是理解作为听力基础的神经编码和计算。所有的声音信息都是通过耳蜗核中的听神经纤维形成的突触呈现给大脑的。在这里，神经中包含的数据分布在各种细胞类型中，每种细胞类型代表声环境的某些特征。耳蜗核神经元及其神经编码构成了中枢听觉通路的基础，而中枢听觉通路最终负责我们定位和识别声音的能力：我们统称为听力的感知。支撑这些感知的神经计算如何以及在哪里发生，将取决于不同类别的耳蜗核神经元产生的轴突路径，以及它们在目标结构中的突触组织。在这个方案中，我们计划研究一大群被称为多极神经元的耳蜗核神经元所承担的轴突通路。我们认为，耳蜗核腹侧区的多极神经元在声信息处理的初始阶段起着关键作用。他们是耳蜗核内部回路的完全参与者，他们的轴突针对听觉通路中的每一个脑干核团。多极神经元是一个不同的群体，这表明它们由几个不同的细胞亚类组成。我们建议使用逆行路径追踪方法来识别不同群体多极神经元的靶点，并使用电生理记录技术来匹配每种类型的轴突路径及其生理反应特性。这些数据将提供关于一大群耳蜗核细胞所扮演的功能角色的新知识，以及对中枢听觉核团进行的神经计算的性质的洞察。

Our long term goal is to understand the neural codes and computations that underlie hearing. All acoustic information is presented to the brain with the synapses formed by auditory nerve fibers in the cochlear nucleus. Here, the data contained in the nerve are distributed amongst a variety of cell types that each represent some feature of the acoustic environment. Cochlear nucleus neurons and their neural codes form the foundation of central auditory pathways that are ultimately responsible for our ability to locate and identify a sound: perceptions that collectively we refer to as hearing. How and where the neural computations that underlie these perceptions occur will depend on the axonal pathways engendered by distinct classes of cochlear nucleus neurons, and their synaptic organizations in the structures that they target. In this proposal, we plan to study the axonal pathways borne by one large group of cochlear nucleus neurons referred to as multipolar neurons. We propose that multipolar neurons in the ventral division of the cochlear nucleus play a key role in the initial stages of acoustic information processing. They are full participants in the intrinsic circuitry of the cochlear nucleus and their axons target every brain stem nucleus in the auditory pathway. Multipolar neurons are a heterogeneous population, suggesting that they are comprised of several distinct subclasses of cells. We propose to use retrograde pathway tracing methods to identify the targets of different populations of multipolar neurons, and electrophysiological recording techniques to match the axonal pathway of each type with its physiological response properties. These data will provide new knowledge with respect to the functional roles served by a large group of cochlear nucleus cells, as well as provide insights into the nature of the neural computations performed in central auditory nuclei.