STRUCTURE AND FUNCTION RELATIONS IN MIDDLE EAR

我们工作的目标是定义与外部和 中耳结构要发挥作用，这样我们才能了解功能 正常变异和病理变异在中耳解剖中的意义。 在本申请中，我们提出了旨在研究 鼓膜、听小骨和听小骨形态的差异 中耳的空气空间会影响中耳的表现。这些过程 受累代表了中耳最外围的动作。二 赠送的分类学团体，将被研究。(1)四种啮齿动物 (灰鼠、沙鼠、仓鼠和老鼠)被选中是因为 他们的中耳和听力图都有明显的差异。这个 结构上的差异在于鼓膜的大小和 听小骨，锤骨悬吊的形状和硬度，相对的 中耳空间的体积，以及中耳空间的相对大小 副鼓膜。生理和解剖学测量 将定量地决定这些结构性因素的影响 不同之处。(2)猫科(猫科)物种的中耳 具有很大的结构一致性，大小变化很大。这个 家猫中耳空气空间的影响是已知的 与频率密切相关，并与双腔有关 猫咪特有的空间配置。使用头骨 从博物馆的收藏品中，我们将对 (本质上)确定该科所有36种植物的数量 将耳朵的大小与头骨大小联系起来的规则。对于一个子集 这些(大约12个物种)更详细地重建了中耳 将通过头骨的CT扫描进行，这将产生3 可用于派生声学模型的维度描述。 将进行声学反应的死后生理测量 6-10种标本(可从动物园和野生动物获得) 科室)，也将根据CT扫描进行解剖重建 从组织切片中提取。相关的定量模型 结构特征和生理性能将开发用于 分类组别和这些模型都将通过测量进行检验。 我们的目标是提供一个统一的理论，在这个理论中，多样化的 这些啮齿动物的结构构型和数量 猫科动物的可变结构包括在数量上 描述这两种变化的功能后果。这 系统的方法将为定量描述生物多样性奠定基础 中耳的病理和种间差异的影响 结构对听觉功能的影响。这样的描述将取代 趣闻轶事描述和全面的理论可以影响 中耳病理与再造的临床认识 作为关于耳朵进化的想法。

The goal of our work is to define rules that relate external and middle-ear structure to function so that we can understand the functional significance of normal and pathologic variations in middle-ear anatomy. In this application we propose experiments designed to investigate how differences in the configuration of the tympanic membrane, ossicles and middle-ear air spaces affect middle-ear performance. The processes involved represent the most peripheral action of the middle ear. Two complimentary taxonomic groups, will be studied. (1) Four rodent species (chinchilla, gerbil, hamster, and rat) have been selected because of distinct differences in both their middle ears and their audiograms. The structural differences are in the size of the tympanic membrane and ossicles, the shape and rigidity of the malleus suspension, the relative volume of the middle-ear air-spaces, and the relative size of the accessory tympanic membrane. Physiological and anatomical measurements will quantitatively determine the effects of these structural differences. (2) The middle-ears of species in the cat family (Felidae) have great structural uniformity with large variations in size. The effects of the middle-ear air spaces in domestic cat are known to be sharply frequency dependent and are related to the two-cavity configuration of the spaces that is characteristic of cats. Using skulls from museum collections we will make structural measurements on (essentially) all 36 species of this family to determine quantitative rules that relate dimensions of the ear to skull size. For a subset of these (about 12 species) more detailed reconstructions of the middle ear will be made from CT scans of the skull, which will yield three dimensional descriptions from which acoustic models can be derived. Post-mortem physiological measurements of acoustic responses will be made on specimens of 6-10 species (as available from zoos and wildlife departments), which will also be reconstructed anatomically from CT scans and from histological sections. Quantitative models relating the structural features and physiologic performance will be developed for both taxonomic groups and these models will tested by the measurements. Our aim is to provide a unified theory in which both the diverse structural configurations of these rodents and the quantitatively variable structure in Felidae are included in rules that quantitatively describe the functional consequences of both kinds of variations. This systematic approach will lay a base for a quantitative description of the effects of pathological and interspecies differences in middle-ear structure on auditory function. Such a description will replace anecdotal descriptions with a comprehensive theory that can impact the clinical understanding of middle-ear pathology and reconstruction as well as ideas about evolution of the ear.