PHYSIOLOGICAL STUDIES OF AGE RELATED HEARING LOSS

描述：总体目标是检查潜在的机制 动物听神经编码的病理生理变化 静静地老去。在过去的10年里，他们成功地开发出了 蒙古沙鼠是人类老年性耳聋的典范。在这份提案中，我们 关注沙土鼠模型中一个已知受以下因素影响的耳蜗电 年龄：侧壁系统产生的耳蜗内电位(EP)。 我们研究了青少年和青少年的EP和神经编码之间的关系。 年迈的动物。具体的焦点是EP在加工过程中的影响 听神经纤维中的时间信息--一个尚未解决的问题 在正常耳蜗文学中，在老年性耳聋中就更不用说了 耳蜗骨。有三个具体目标。特指1检查神经 青年和老年人听神经时序信息的编码 沙鼠。实验包括单纤维研究和种群研究 使用复合动作电位(CAP)。需要检验的假设是 随着年龄的增长，安静年龄的动物的时间编码会变得有缺陷。 特指2急性操纵老年沙土鼠和幼年沙土鼠的EP进行测试 认为EP在编码过程中起基础作用的假设 听神经活动中的时间信息。特指三考 幼年沙土鼠在慢性低EP条件下的神经编码。 降低的EP将通过向耳蜗内注射速尿来维持 使用植入的插管和渗透泵进行为期数周的 长达几个月。以前的研究支持这样的假设；安静的老年人 沙土鼠耳蜗可以被模拟为一个完整的毛细胞系统，在 低EP的条件。最终目的是建立老年性耳聋模型。 幼年动物的耳蜗，从而极大地提高了 老年性耳聋的动物模型研究。

DESCRIPTION: The overall aim is to examine the mechanisms underlying pathophysiologic changes in neural coding in the auditory nerves of animals aged in quiet. Over the past 10 years they have successfully developed the Mongolian gerbil as a model of human presbyacusis. In this proposal we focus on one cochlear potential in the gerbil model known to be affected by age: the endocochlear potential (EP) produced by the lateral wall system. We examine the relationship between the EP and neural coding in young and aged animals. Specific focus is on the effects of EP on the processing of temporal information in auditory nerve fibers, an aspect not yet addressed in the literature in the normal cochlea, much less in the presbyacusic cochlea. There are three specific aims. Specific aim 1 examines neural coding of timing information in the auditory nerves of young and quite-aged gerbils. Experiments include single fiber studies and population studies using the compound action potential (CAP). The hypothesis to be tested is that temporal coding in quiet-aged animals becomes deficient with age. Specific Aim 2 acutely manipulates the EP in old and young gerbils to test the hypothesis that the EP plays a fundamental role in the coding of temporal information in auditory-nerve activity. Specific Aim 3 examines neural coding under conditions of a chronically low EP in young gerbils. The lowered EP will be maintained by infusing furosemide into the cochlea with an implanted cannula and osmotic pump over periods ranging from weeks to months. Previous work supports the hypothesis that ;the quiet-aged gerbil cochlea can be modeled as an intact hair cell system operating under conditions of a low EP. The last aim will establish a model of presbyacusic cochlea in a young animal, thereby greatly enhancing the efficiency of studies of presbyacusis in animal models.