FUNCTIONAL PATHWAYS OF THE COCHLEAR NUCLEUS

我们的长期目标是理解听觉背后的神经编码和计算。所有的声音信息都是通过耳蜗核中听神经纤维形成的突触传递给大脑的。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。耳蜗核神经元和它们的神经编码构成了中枢听觉通路的基础，中枢听觉通路最终负责我们定位和识别声音的能力：我们统称为听觉的感知。这些感知背后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通路，以及它们在目标结构中的突触组织。在这一提议中，我们计划研究由一大群耳蜗核神经元所承载的轴突通路，称为多极神经元。我们认为，耳蜗核腹侧分裂的多极神经元在声学信息处理的初始阶段起着关键作用。它们完全参与了耳蜗核的内在回路，它们的轴突以听觉通路中的每个脑干核为目标。多极神经元是一个异质性的群体，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多极神经元群体的目标，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大量耳蜗核细胞的功能作用的新知识，并提供对中央听核进行神经计算的本质的见解。

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.