LEAD EFFECTS ON THE AUDITORY SYSTEM IN MAMMALS

早期接触铅似乎会对听觉造成有害影响 流程。不仅是基本的心理声学和电生理学 受影响的措施，但也包括更高级别的过程，如语音 感知和语言理解。很可能这种听觉上的 系统病理有助于产生更多的全球行为后果 阅读技能、学校问题和智商缺陷 儿童时期接触过铅。这项研究的目标是界定 与儿童铅暴露有关的听觉病理学的性质 实验，非人类灵长类动物模型(恒河猴)。我们的目标是评估 外周和中枢听觉系统对此的贡献 异常，并表征外生因素的贡献， 例如，使用行为学对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，改变干预计划的组成，以及 为确定更广泛的调查是否 潜在的病理生理学是有根据的。 猴子在整个怀孕期间或在一段时间内每天都暴露在铅中 可比较的出生后从出生开始的时间。铅暴露水平为 与人类童年时期铅暴露相关的水平。对照猴子是 没有额外的领先优势。这些猴子现在9岁了，有广泛的 实验测试记录。对这些猴子和其他猴子的初步研究 用电生理指标显示铅对外周和外周的影响 更高级的听觉过程。几个信号的潜伏期和幅度 脑干听觉诱发反应的成分增加和 复合音(音素)辨别的电生理指标 随着铅暴露时间的不同而发生改变 暴露会产生不同的结果模式。行为测量： 在早期接触铅之后，注意力也被扰乱了 歧视研究。 建议对听觉系统完整性进行进一步测试，包括 绝对阈值和差异阈值、行为测量的行为测量 注意过程的测量，辨别的行为测量 包括人类语音的复杂听觉刺激，并且还 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.