Age related effects on macaque auditory cortex

描述(由申请人提供)： 听力障碍是导致老年人残疾的第三大原因。在美国70岁以上的所有人中，超过一半的人患有某种形式的与年龄相关的听力障碍。这是一个普遍存在的问题，有很多来源，外周因素对年龄相关的缺陷，特别是高频听力损失，已经进行了探索，并揭示了这些疾病的几个重要特征。然而，关于年龄相关性听力损失和正常衰老对中枢听觉结构，特别是新皮质的影响，以及中枢结构解剖或生理过程中与年龄相关的变化如何导致知觉缺陷，人们仍然知之甚少。我们缺乏对这些中枢影响的了解，很大程度上是因为缺乏有效的动物模型，该模型(1)与人类分享许多听觉皮质的组织特征，(2)具有相当长的寿命，使得与年龄相关的听力障碍像人类一样在几年的过程中发展，以及(3)不是令人望而却步的昂贵。我有一个独特的机会来开发这样一个动物模型，因为我可以接触到一个满足这三个标准的大型老年猕猴群体。这项建议的目标是确定哪些听觉皮质反应特性受正常衰老和年龄相关性听力损失的影响最大。在这些实验中将使用两只正常的幼年动物，两只患有年龄相关性高频听力损失的老年动物，以及两只年龄匹配的没有年龄相关性听力损失的老年动物。单个神经元在初级和次级听觉皮质区的光谱、空间和时间反应特性将在每个猴子身上定义。不同猴子的神经元以及由于高频听力损失而重组的听觉皮质区域的神经元之间的比较将被比较，以确定听觉信息处理的哪些方面最容易受到老化和年龄相关性听力损失的影响。这项研究的结果将为未来旨在为患有年龄相关性听力障碍的个人开发补救治疗和疗法以及助听器设计的研究计划提供基础。

DESCRIPTION (provided by applicant): Hearing deficits are the third leading cause of disability in the aged. Over half of all people in the US over seventy suffer some form of age-related hearing deficits. This is a ubiquitous problem with many sources, and the peripheral contributions to age-related deficits, particularly high frequency hearing loss, have been explored and have revealed several important features of these disorders. However, there remains relatively little understood about the consequences of age-related hearing loss and normal aging on central auditory structures, particularly the neocortex, and how age-related changes in either anatomical or physiological processes in central structures give rise to perceptual deficits. Our lack of understanding of these central effects is due in large part to the lack of an effective animal model that (1) shares many organizational features of auditory cortex with humans, (2) has a reasonably long life span such that age-related hearing deficits progress over the course of several years as in the human, and (3) are not prohibitively expensive. I have a unique opportunity to develop such an animal model as I have access to a large geriatric colony of macaque monkeys that satisfy these three criteria. The goals of this proposal are to determine which auditory cortical response properties are most influenced by normal aging and age-related hearing loss. Two normal young animals, two older animals with age- related high frequency hearing loss, and two older age-matched animals without age-related hearing loss will be used in these experiments. Spectral, spatial, and temporal response properties of single neurons in primary and secondary auditory cortical fields will be defined in each, monkey. Comparisons between neurons in different monkeys, as well as in auditory cortical fields that have been reorganized due to the high frequency hearing loss, will be compared to determine which aspects of auditory information processing are most susceptible to aging and age-related hearing loss. The results of this study will provide the foundation for future research programs aimed at the development of remedial treatments and therapies, as well as in hearing aid design, for individuals suffering from age-related hearing deficits.