Cortical correlates of age-related hearing deficits

描述（由申请人提供）：听力障碍是老年人残疾的第三大原因。在美国，超过一半的70岁以上的人患有某种形式的与年龄有关的听力缺陷。这是一个普遍存在的问题，有许多来源，和周边贡献的年龄相关的缺陷，特别是高频听力损失，已被探索，并揭示了这些疾病的几个重要特征。然而，对于年龄相关性听力损失和正常衰老对中枢听觉结构（特别是新皮层）的影响，以及中枢结构中解剖学或生理学过程的年龄相关性变化如何导致感知缺陷，仍然知之甚少。我们对这些中枢效应缺乏了解，在很大程度上是因为缺乏一种有效的动物模型，这种动物模型（1）与人类具有许多听觉皮层的组织特征，（2）具有相当长的寿命，使得与年龄相关的听力障碍在几年的时间内发展，就像人类一样，（3）不是过于昂贵。该提案的目标是通过将与年龄或听力损失相关的听力缺陷与听觉皮层核心和带状区域中的单个神经元活动以及同一个体的感知能力和耳蜗形态相关联来填补这一空白。实验组将包括无听力损失的幼龄动物、听力损失的幼龄动物、极轻微听力损失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，皮质活动将与这种行为表现、听力阈值和耳蜗形态直接相关。将比较不同动物的神经元之间的比较，以及由于高频听力损失而重组的听觉皮层领域，以确定听觉信息处理的哪些方面最容易受到衰老和与年龄相关的听力损失的影响。这项研究的结果是开发新的补救治疗和疗法以及助听器设计的关键一步，适用于患有与年龄相关的听力缺陷的个人。

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.