LEAD EFFECTS ON THE AUDITORY SYSTEM IN MAMMALS

早期接触铅似乎会对听力造成有害影响 流程. 不仅是基本的心理声学和电生理学 受影响的措施，但也更高阶的过程，如语音 感知和语言理解。 很可能这种听觉 系统病理学有助于更多的全球行为后果， 阅读技能，学校问题，和智商缺陷的特点， 儿童铅暴露。 本研究的目的是确定 与儿童期铅暴露相关的听觉病理学性质 实验性非人灵长类动物模型（恒河猴）。 我们的目标是评估 周边和中央听觉系统的贡献，这些 异常，并表征外源因素的贡献， 例如使用行为的听觉病理的注意过程， 和神经生理学技术。 这些研究的结果将影响 筛查方法，改变干预方案的组成， 为确定是否进行更广泛的调查提供依据。 潜在的病理生理学是有根据的 猴子在整个妊娠期每天接触铅， 从出生开始的出生后时间。 铅暴露在 与人类儿童期铅暴露相关的水平。 对照组猴子 没有额外的铅。 这些猴子现在9岁了， 实验测试历史 对这些和其他猴子的初步研究 使用电生理指标表明铅对外周和 高阶听觉过程 几个信号的振幅和振幅 脑干听觉诱发反应的成分增加， 复杂音（音素）辨别的电生理学指标 随着铅暴露时间的不同， 暴露产生不同的结果模式。 行为测量 注意力也被打乱后，早期铅暴露在 歧视研究。 提出了进一步的听觉系统完整性测试，包括 绝对和差异阈值的行为测量，行为 注意力过程的测量， 包括人类语音的复杂听觉刺激，以及进一步 分析对听觉刺激的电生理反应，包括 脑干听觉反应

Early exposure to lead appears to cause deleterious effects on auditory processes. Not only are basic psychoacoustic and electrophysiological measures affected, but also higher-order processes such as speech perception and language comprehension. It is likely that such auditory system pathology contributes to more global behavioral consequences for reading skills, school problems, and IQ deficits characteristic of childhood lead exposure. The objectives of this research are to define the nature of auditory pathologies related to childhood lead exposure for an experimental, nonhuman primate model (rhesus monkey). We aim to evaluate contributions of the peripheral and central auditory system to these abnormalities, and to characterize the contribution of exogenous factors, such as attentional processes to the auditory pathology using behavioral and neurophysiologic techniques. Results of these studies would affect screening methods, alter the composition of intervention programs, and provide the basis for determining whether a more extensive investigation of the underlying pathophysiology are warranted. Monkeys were exposed to lead daily either throughout gestation or for a comparable time postnatally beginning at birth. Lead exposure was at levels relevant to human childhood lead exposure. Control monkeys were given no added lead. The monkeys are now 9 years old and have extensive experimental test histories. Initial studies with these and other monkeys using electrophysiologic indices indicate effects of lead on peripheral and higher order auditory processes. Latencies and amplitudes of several components of the brainstem auditory evoked response were increased and electrophysiological indices of discrimination of complex sounds (phonemes) were altered as a function of lead exposure with different periods of lead exposure producing different patterns of results. Behavioral measures of attention also were disrupted following early lead exposure in the discrimination studies. Further tests of auditory system integrity are proposed including behavioral measurements of absolute and difference threshold, behavioral measures of attentional processes, behavioral measures of discrimination of complex auditory stimuli including human speech sounds, and further analysis of electrophysiologic responses to auditory stimuli including the brainstem auditory response.