CODING IN AUDITORY NEURONS EFFECTS OF AMINO ACIDS

重要的是要了解神经化学方面的感觉 因为可以想象，许多神经系统 异常，如接受性失语，神经性耳聋，听觉 知觉功能障碍和感觉诱发的癫痫发作涉及神经化学 故障 这项研究将继续努力查明和 表征介导突触传递的神经递质， 中枢听觉通路的特定部位。 微离子电渗疗法将是 用于应用假定的神经递质及其各自的拮抗剂 在模拟（作用的同一性）和拮抗（药理学）试验中 身份）的突触释放的化合物。 阈值的变化， 自发活动、反应模式和频率-强度函数将 检查脑干听觉结构中的神经元。 推定 待测试的神经递质基于形态学选择， 生理学、神经化学和组织化学信息。 双耳 上级橄榄复合体（SOC）中的神经元提供了一个机会， 选择性地控制对给定神经元的突触兴奋和抑制， 操纵每个耳朵的声音输入。 我们最近的发现 表明甘氨酸可能介导某些SOC双耳抑制 神经元 第二种抑制性神经递质GABA的作用， 兴奋性氨基酸在SOC突触中的作用将用 选择的氨基酸受体拮抗剂。 巴氯芬，一种拟议的抑制剂 兴奋性氨基酸释放，减少神经元的反应， 耳蜗核（CN）。 这种药物的效果和最近可用的 将在SOC中检查兴奋性氨基酸的特异性拮抗剂 并将被用于进一步检验一种兴奋性氨基酸 是听觉神经突触的传递器。 细胞内记录 将被用作CN中作用同一性的更严格测试。 的 提出了神经生理学和神经药理学技术的组合 应该有助于识别听觉神经递质， 阐明其在编码过程中的作用。

It is important to understand the neurochemical aspects of sensory processing since it is conceivable that a number of neurologic abnormalities such as receptive aphasia, neural prebycusis, auditory perceptual dysfunction and sensory-induced seizures involve neurochemical fault(s). This study will continue the attempt to identify and characterize the neurotransmitters which mediate synaptic transmission at specific sites in the central auditory pathway. Microiontophoresis will be used to apply putative neurotransmitters and their respective antagonists in tests of mimicry (identity of action) and antagonism (pharmacologic identity) of the synaptically released compound. Alterations of threshold, spontaneous activity, response patterns, and rate-intensity functions will be examined for neurons in brainstem auditory structures. Putative neurotransmitters to be tested are selected based on morphologic, physiologic, neurochemical, and histochemical information. Binaural neurons in the superior olivary complex (SOC) provide an opportunity to selectively control synaptic excitation and inhibition to a given neuron by manipulation of the acoustic input to each ear. Our recent findings suggest that glycine may mediate binaural inhibition in certain SOC neurons. The action of a second inhibitory neurotransmitter, GABA, and the role of excitant amino aicds at SOC synapses will be examined using selected amino acid receptor antagonists. Baclofen, a proposed inhibitor of excitant amino aicd release, reduces the response of neurons in the cochlear nucleus (CN). The effect of this drug and recently available specific antagonists of excitant amino acids will be examined in the SOC and will be used to further test the hypothesis that an excitant amino acid is the transmitter at acoustic nerve synapses. Intracellular recordings will be used as a more rigorous test of identity of action in the CN. The combination of neurophysiologic and neuropharmacologic techniques proposed should aid in the identification of auditory neurotransmitters and an elucidation of their role in the coding process.