PROCESSING AM SIGNALS IN AUDITORY SYSTEM

这项研究计划的长期目标是了解交流声音中的时间模式是如何在中央听觉系统中表现和处理的。通信信号中的许多信息，包括人类语言，都存在于它们的时间结构中。因此，了解声音的时间结构是如何在神经系统中表示和处理的，对于理解沟通和沟通障碍的神经基础至关重要。这项研究将对无尾目动物的听觉系统进行，因为它们发声的时间结构已经被证明在它们的生殖生物学中很重要，并且可以进行行为研究来描绘它们的时间处理能力。目前，关于听觉系统中时间加工的神经机制知之甚少。在基本层面上，声音的时间结构包括其幅度和频率如何随时间变化，即如何被调制。这个研究项目的具体目标是深入了解幅度调制在大脑中是如何表示的，以及这些表示中的转换。在包括哺乳动物在内的许多脊椎动物中，存在着从幅度调制速率的周期性编码到AM滤波表示的转换；中脑中的大多数神经元在AM速率的特定范围内反应最好，即带通。人们对这种转变背后的机制知之甚少。本研究方案中概述的具体实验旨在测试有关产生带通AM选择性的假设。将研究恢复过程和时间整合的作用。其他实验应该能揭示中脑中是否存在“AM图”。

The long-term objectives of this research program are to understand how temporal patterns in communication sounds are represented and processed in the central auditory system. Much of the information in communication signals, including human language, resides in their temporal structure. An understanding of how the temporal structure of sounds is represented and processed in the nervous system, therefore, is vital to understanding the neural bases of communication and communicative disorders. The research will be conducted on the auditory system of anurans because the temporal structure of their vocalizations has been shown to be important in their reproductive biology and behavioral studies can be conducted to delineate their temporal processing abilities. Presently, little is known concerning the neural mechanisms of temporal processing in the auditory system. At a basic level, the temporal structure of sound consists of how its amplitude and frequency changes, i.e., is modulated, over time. The specific goals of this research project are to gain insight into how amplitude modulations are represented in the brain and the transformations in these representations. In a number of vertebrate species, including mammals, there is a transformation from a periodicity coding of the rate of amplitude modulation to an AM filter representation; most neurons in the midbrain respond best over a particular range of AM rate, i.e., are band-pass. The mechanisms underlying this transformation are poorly understood. The specific experiments outlined in this research proposal are designed to test hypotheses concerning the generation of band-pass AM selectivity. The roles of recovery processes and temporal integration will be investigated. Other experiments should reveal whether an 'AM map' exists in the midbrain.