PARALLEL AUDITORY PATHWAYS IN THE BRAIN STEM

下丘中央核(ICC)是 自下而上的多条专用并行路径的汇聚 脑干。因此，国际刑事法院是第一个阶段，有重大的 双耳专用通路的输入整合 比较、频谱分析和时间模式分析。大号 对ICC的投入比例似乎要么是GABA能的，要么是 甘氨酸能，提示抑制可能在 综合流程。拟议研究的目的是调查 假设：1)抑制性输入在环境中起着关键作用 增强或降低对声音的敏感性的声音诱发窗口 随后的声音，以及2)对大脑中单个神经元的抑制性输入 ICC塑造了它们的光谱敏感性。使用回声定位蝙蝠是因为 我们从它们的生物声纳信号中了解到 在生物学上具有重要的意义。然而，基础神经 锐化光谱灵敏度和创建滤光片的机制 声音的特定时间模式很可能与 对包括语音在内的所有复杂声音的神经处理。具体的 目的如下：1)确定声音诱发的颞叶起源 对后续声音的响应度增加或降低的窗口 测试时间窗是否构成神经元选择性的基础 对于特定的声音模式，如调幅速率；2) 确定声音诱发的敏感度窗口是启动还是 由核单声道计时通路的输入控制 外侧丘疹；3)确定光谱敏感性是否 通过国际刑事法院的抑制机制进行强化；4)确定 抑制受体的分布与功能特性有关，如 作为时间和光谱的选择性。将使用多种方法 来解决这些问题。其中包括：细胞外 单个神经元的电生理记录，解剖示踪 方法，免疫细胞化学；受体放射自显影，神经药理学 对于单个神经元，活体全细胞膜片钳技术。数据 所获得的结果应该为以下神经机制提供新的见解 分析复杂的声音模式。例如，数据应该 解释基本现象，例如锁相响应如何 在脑干水平上的幅度调制在 中脑，到时间过滤器，对窄率的 调制。

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.