Cortical correlates of age-related hearing deficits

描述(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。这项建议的目标是通过将与年龄或听力损失有关的听力障碍与听觉皮质核心和带状区域的单个神经元活动以及相同个体的感知能力和耳蜗形态联系起来，来填补这一空白。实验组将包括没有听力损失的幼年动物、听力损失的幼年动物、听力损失轻微的老年动物和听力损失的老年动物。动物将接受空间和时间辨别任务的训练，大脑皮层活动将与这种行为表现、听力阈值和耳蜗形态直接相关。不同动物中神经元之间的比较，以及由于高频听力损失而重组的听觉皮质区域，将进行比较，以确定听觉信息处理的哪些方面最容易受到老化和与年龄相关的听力损失的影响。这项研究的结果是为患有年龄相关性听力障碍的个人开发新的补救疗法和疗法以及助听器设计的关键一步。

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. The goals of this proposal are to fill this gap by correlating hearing deficits related to either age or hearing loss with single neuron activity in core and belt areas of auditory cortex as well as the perceptual abilities and the cochlear morphology of the same individuals. Experimental groups will include young animals with no hearing loss, young animals with hearing loss, geriatric animals with minimal hearing loss and geriatric animals with hearing loss. Animals will be trained on spatial and temporal discrimination tasks and cortical activity will be directly correlated with this behavioral performance, hearing thresholds, and cochlear morphology. Comparisons between neurons in different animals, 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 are a critical step in the development of new remedial treatments and therapies, as well as in hearing aid design, for individuals suffering from age-related hearing deficits.