AUDITORY SYSTEM RESPONSE TO AIRBORNE AND SEISMIC STIMULI

该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限制。特别是，本研究的主要目标是了解和评价空气、基质和组合（双峰）刺激接受的机械和电气因素，并进一步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，为了a (a)直接测量两栖动物中耳听骨在空气声音、基材振动和双峰刺激下的运动，从而更精确地定义这些结构在低频接收中的作用，将进行一系列五项详细的研究。(b)表征另外两种“低频”动物——普通鼹鼠和金鼹鼠——中耳小骨的空气和地震响应特性，从而将我们的观察扩展到化石哺乳动物；(c)量化顶盖膜对低频声音和振动的响应程度，以阐明这种结构在双峰加工中的作用；(d)通过跟踪去极化响应的相关电容变化，系统地比较两栖动物乳头的低频（双峰）和高频（单峰）毛细胞的突触释放；(e)将声学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的双峰纤维。这种综合结构-功能和神经行为学方法所产生的数据将对声-振动复合物处理的解剖学和神经基质具有丰富的含义；因此，这项工作有望为理解包括人类在内的动物的空气传导和骨传导声音传播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.