AUDITORY SYSTEM RESPONSE TO AIRBORNE AND SEISMIC STIMULI

这项研究的总体目标是定量描述脊椎动物听觉系统中低频选择性的结构和生理约束。特别是，拟议研究的主要目标是了解和欣赏空气、基质和组合(双峰)刺激接收背后的机械和电气因素，并进一步深入了解影响脊椎动物内耳调谐的刺激相互作用的机制。为了实现这些目标，将进行一系列五项详细研究，以便：(A)直接测量两栖动物中耳听小骨对空气传播的声音、底物传播的振动和双峰刺激的反应，从而更准确地确定这些结构在低频接收中的作用；(B)描述另外两种“低频”动物--普通鼹鼠和金鼹鼠--的中耳听骨的空气传播和地震响应特性，从而将我们的观察扩展到化石哺乳动物，(C)量化盖层膜对低频声音和振动的反应程度，以阐明这一结构在双峰处理中的作用；(D)通过跟踪两栖动物乳头毛细胞对去极化反应的相关电容变化，系统地比较低频(双峰)和高频(单峰)毛细胞的突触释放；以及(E)将我们对声波和地震刺激之间的非线性相互作用的研究扩展到第八神经中的双峰纤维。这种综合的结构-功能和神经行为学方法产生的数据将对声音-振动复合体处理的解剖学和神经基础产生丰富的影响；因此，这项工作有望为理解包括人类在内的动物中空气传导和骨传导的声音传递之间的关系提供一个框架。

The overall goal of the proposed research is a quantitative description of the structural and physiological constraints on low-frequency selectivity in the vertebrate auditory system. In particular, the primary objectives of the proposed research are to gain an understanding and appreciation of the mechanical and electrical factors underlying airborne, substrate-borne and combination (bimodal) stimulus reception, and to provide further insight into the mechanisms underlying stimulus interactions which affect tuning in the vertebrate inner ear. To accomplish these objectives, a series of five detailed investigations will be performed in order to a (a) directly measure the motion of the middle ear ossicles in amphibians in response to airborne sound, substrate-borne vibration and bimodal stimulation, and thus more precisely define the role of these structures in low-frequency reception, (b) characterize the airborne and seismic response properties of the middle ear ossicles of two other "low- frequency" animals- the common and golden mole- and thus extend our observations to fossorial mammals, (c) quantify the extent to which the tectorial membrane responds to low-frequency sound and vibration in order to elucidate the role of this structure in bimodal processing, (d) systematically compare synaptic release in low-frequency (bimodal) and high-frequency (unimodal) hair cells from the amphibian papilla by tracking correlated capacitance changes in response to depolarization, and (e) extend our investigation of the nonlinear interactions between acoustic and seismic stimuli to the bimodal fibers in the eighth nerve. The data that result from this integrative structure-functional and neuroethological approach will be rich in implications regarding the anatomical and neural substrates underlying the processing of sound-vibration complexes; thus this work is expected to provide a framework for understanding the relationship between air-conducted and bone-conducted sound transmission in animals, including humans.