CODING IN AUDITORY NEURONS: EFFECTS OF AMINO ACIDS

临床异常如接受性失语、听觉知觉 功能障碍和神经性老年性耳聋可能涉及神经化学故障， 中央听觉通路 了解神经化学基础 这些结构中的感觉处理可能导致代理的发展 来治疗这些临床症状 上级橄榄复合体（SOC）和 耳蜗核（CN）是听觉信号处理的重要结构 信息. 拟议的研究将继续确定、表征 并评估这些听觉神经递质的作用 结构. 对龙猫CN和SOC的研究旨在检查 抑制性和兴奋性氨基酸类神经递质在脑缺血中的作用 编码过程 细胞外离子电渗研究将用于 研究GABA和甘氨酸在编码特异性抑制蛋白中的作用。 耳蜗背核（DCN）神经元的反应。 甘氨酸 拮抗剂，士的宁，已被证明可以阻断抑制， 某些DCN神经元的非单调率强度函数。 的作用 兴奋性神经递质在产生特异性反应中的作用 在斜方体内侧核（MNTB）和外侧核的模式 还将检查上级橄榄核（LSO）。 先前 在这个实验室的离子电渗研究已经检查了主要的 LSO的神经元对双耳刺激表现出抑制作用。 甘氨酸被认为是一种抑制性神经递质， 从MNTB投射到LSO神经元的神经元。 初步 细胞内数据表明，抑制性突触后电位（IPSP） 对侧刺激诱发的双耳抑制 LSO。 将尝试描述振幅、持续时间和 这个IPSP的逆转潜力。 甘氨酸的离子电渗应用， 其受体拮抗剂士的宁将能够进行模仿试验（身份 作用）和拮抗作用（药理学特性） 突触释放的神经递质介导对侧诱发的 IPSP。 以后的研究也将描述同侧诱发的EPSP 在我们的初步研究中发现。 结合这些 实验，使用辣根的细胞内记录标记研究 过氧化物酶（HRP）将使我们能够更好地建立一个结构-功能 LSO的主要神经元的相关性。 从这些 研究应有助于更好地了解 正常成人听觉信息加工中的神经递质 动物，并导致未来的研究潜在的神经递质为基础的 听觉障碍

Clinical abnormalities such as receptive aphasia, auditory perceptual dysfunction and neural presbycusis may involve neurochemical fault(s) of the central auditory pathway. Understanding the neurochemical basis of sensory processing in these structures could lead to development of agents to treat these clinical conditions. The superior olivary complex (SOC) and cochlear nucleus (CN) are important structures in processing acoustic information. The proposed studies will continue to identify, characterize and evaluate the role of putative neurotransmitters in these auditory structures. Studies in the chinchilla CN and SOC are designed to examine the role of inhibitory and excitatory amino acid neurotransmitters in the coding process. Extracellular iontophoretic studies will be used to examine the role of GABA and glycine in the coding of specific inhibitory responses seen for dorsal cochlear nucleus (DCN) neurons. The glycine antagonist, strychnine, has been shown to block suppression seen as nonmonotonic rate-intensity functions for certain DCN neurons. The role of excitatory neurotransmitters in the generation of specific response patterns in the medial nucleus of the trapezoid body (MNTB) and the lateral superior olivary (LSO) nucleus will also be examined. Previous iontophoretic studies in this laboratory have examined the principal neurons of the LSO which display inhibition upon binaural stimulation. Glycine has been implicated as an inhibitory neurotransmitter released by neurons projecting from the MNTB onto LSO neurons. Preliminary intracellular data suggest that inhibitory postsynaptic potential (IPSP) evoked by contralateral stimulation subserves binaural inhibition in the LSO. Attempts will be made to characterize the amplitude, duration and reversal potential of this IPSP. Iontophoretic application of glycine and its receptor antagonist, strychnine, will enable tests of mimicry (identity of action) and antagonism (pharmacologic identity) of the synaptically-released neurotransmitter mediating the contralaterally-evoked IPSP. Later studies will characterize the ipsilaterally-evoked EPSP also observed in our preliminary studies. In conjunction with these experiments, intracellular record-marking studies using horseradish peroxidase (HRP) will allow us to better establish a structure-function correlation for the principal neurons of the LSO. Results from these studies should lead to a better understanding of the role of neurotransmitters in processing the acoustic message in normal adult animals and lead to future studies on potentially neurotransmitter-based acoustic disorders.