Corticofugal Regulation of Central Auditory Sensitivity

人类和动物处理复杂声音所携带的听觉信息是如此容易和快速。 这种有效的信号处理是基于在中央听觉系统中发生的巨大计算。 听觉生理学家解释说，听觉信号处理或中枢听觉神经元的反应特性是由上行听觉系统内的发散和会聚投射引起的。 然而，最近的研究表明，离皮质（下行）系统在信号处理中起着非常重要的作用。 已有研究表明，离皮质系统通过高度集中的正反馈与广泛分布的侧抑制共同作用来调节皮层下听觉信号处理。 以蝙蝠作为哺乳动物模型系统，本研究将收集三个假设驱动的实验数据，以形成一个假设的中脑听觉信息加工的离皮质调节的工作模型。 这些研究涉及自由场刺激条件下的电生理学和离子导入法。 具体而言，本申请将研究（1）离皮质系统如何促进或抑制中脑听觉核（下丘）外部和中央部分神经元的听觉反应特性（2）下丘这两个部分的神经元如何在声音刺激期间相互作用以及（3）可能参与这些听觉信息传递的可能神经递质。 对离皮质系统的研究将有助于建立一个更真实、更动态的中枢听觉信号处理模型。 特别是，所收集的数据将有助于了解离皮质系统如何有助于皮层下听觉核的上行听觉信号处理的优化和重组。 这项研究将促进我们对离皮质系统在中央声信号处理过程中的功能作用的理解，直到最近才受到很少的关注。

Humans, and animals process auditory information carried by complex sounds so easily and so fast. This efficient signal processing is based on enormous computation taking place in the central auditory system. Auditory physiologists have explained that auditory signal processing or the response properties of central auditory neurons are resulted from divergent and convergent projections within the ascending auditory system. However, recent studies have shown that the corticofugal (descending) system plays a very important role in signal processing. It has been suggested that the corticofugal system regulates subcortical auditory signal processing through a highly focused positive feedback which works together with a wide spread lateral inhibition. Using bats as a mammalian model system, this proposal will collect data from three hypothesis-driven experiments in order to form a hypothetical working model for corticofugal regulation of midbrain auditory information processing. These studies involve electrophysiology and iontophoresis under free field stimulation conditions. Specifically, this application will study (1) how corticofugal system may facilitate or inhibit auditory response properties of neurons in the external and central parts of a midbrain auditory nucleus (the inferior colliculus) (2) how neurons in these two parts of the inferior colliculus may interact during sound stimulation and (3) the possible neurotransmitters that may be involved in these auditory information transmissions. The proposed study of the corticofugal system will contribute significantly to the development of a more realistic and dynamic model of central auditory signal processing. In particular, the data to be collected will help understand how the corticofugal system contributes to the optimization and reorganization of ascending auditory signal processing in subcortical auditory nucleus. This proposed study will advance our understanding of the functional role of the corticofugal system during central acoustic signal processing which has been given little attention until recently.