PARALLEL AUDITORY PATHWAYS IN THE BRAIN STEM

下丘中央核（ICc）是 多个专门的平行通路从下到上的汇聚 脑干 因此，国际刑事法院是第一个阶段， 专门用于双耳的通路的输入的整合 比较、频谱分析和时间模式分析。 大 ICc的输入比例似乎是GABA能的， 甘氨酸能，这表明抑制可能发挥主要作用， 整合过程 拟议研究的目的是调查 假设：1）抑制性输入在情境中起着重要作用 声音诱发的窗口增加或减少的敏感性， 随后声音，和2）抑制性输入到单个神经元在 ICc塑造了它们的光谱灵敏度。 使用回声定位蝙蝠是因为 我们从他们的生物声纳信号中得知 在生物学上很重要。 然而，基本的神经 用于锐化光谱灵敏度和创建滤波器的机制 声音的特定时间模式可能与 神经处理所有复杂的声音，包括语音。 具体 目的如下：1）确定声音诱发的时间的起源 对后续声音的反应性增加或减少的窗口， 测试时间窗口是否构成神经元选择性的基础 对于特定的声音模式，例如幅度调制的速率; 2） 确定是否启动了声音诱发的灵敏度窗口，或者 控制的输入从单耳定时途径的核 外侧丘系; 3）确定光谱敏感性是否 通过ICc的抑制机制锐化; 4）以确定是否 抑制性受体分布与功能特性有关， 时间和光谱选择性。 将采用多种方法 来解决这些问题。这些包括：细胞外 单神经元电生理记录，解剖描记 方法，免疫细胞化学，受体放射自显影，神经药理学 单神经元，在体内全细胞膜片钳技术。 数据 获得应该提供新的见解神经机制， 分析复杂的声音模式 例如，数据应 解释基本现象，例如锁相响应如何 在脑干水平的振幅调制被转换，在 中脑，时间过滤器，是选择性的狭窄率， 调变

The central nucleus of the inferior colliculus (ICc) is the site of convergence of multiple specialized parallel pathways from the lower brainstem. Thus, the ICc is the first stage at which there is major integration of the inputs of pathways specialized for binaural comparison, spectral analysis and temporal pattern analysis. A large proportion of input to the ICc appears to be either GABAergic or glycinergic, suggesting that inhibition may play a major role in the integrative process. The aim of the proposed studies is to investigate the hypotheses: 1) that inhibitory inputs play a crucial role in setting up sound-evoked windows of increased or decreased sensitivity to a subsequent sound, and 2) that inhibitory inputs to single neurons in the ICc shape their spectral sensitivity. Echolocating bats are used because we know from their biosonar signals which temporal and spectral features of sound are biologically important. However, the basic neural mechanisms for sharpening spectral sensitivity and for creating filters to specific temporal patterns of sound are likely to be relevant for neural processing of all complex sounds including speech. The specific aims are as follows: 1) to determine the origins of sound-evoked temporal windows of increased or decreased responsiveness to subsequent sounds and test whether temporal windows form the basis for a neuron's selectivity for specific sound patterns such as rate of amplitude modulation; 2) to determine whether sound-evoked windows of sensitivity are initiated or controlled by inputs from the monaural timing pathways of the nuclei of the lateral lemniscus; 3) to determine whether spectral sensitivity is sharpened by inhibitory mechanisms at the ICc; 4) to determine whether inhibitory receptor distribution is related to functional properties such as temporal and spectral selectivity. A variety of methods will be used to address these questions. These include: extracellular electrophysiological recording of single neurons, anatomical tracing methods, immunocytochemistry; receptor autoradiography, neuropharmacology of single neurons, in vivo whole-cell patch-clamp techniques. The data obtained should provide new insights into the neural mechanisms for analyzing complex patterns of sound. For example, the data should explain fundamental phenomena, such as how phase-locked responses to amplitude modulation at the brainstem level are transformed, at the midbrain, to temporal filters that are selective for narrow rates of modulation.