Processing AM signals in the auditory system.

描述（由申请人提供）：本研究计划的长期目标是了解交流声音的时间模式如何在中央听觉系统中表示和处理。通信信号（包括人类语音）中的大部分信息都存在于它们的时间结构中，而处理时间信息的缺陷是语音识别障碍的基础。因此，了解声音的时间结构在神经系统中是如何表现和处理的，对于理解交流和交流障碍的神经基础至关重要。这项研究将在无尾两栖类的听觉系统上进行，因为它们发声的时间结构已被证明在其生殖生物学中很重要，而且它们非常适合对时间处理机制进行神经生理学研究。目前，很少有人知道有关的听觉系统的时间处理的神经机制。在基本层面上，声音的时间结构包括其振幅和频率如何变化，即，随着时间的推移，该研究项目的具体目标是深入了解幅度调制（包括脉冲持续时间和上升时间）在大脑中的表现方式以及这些表现中的转换机制。在包括哺乳动物在内的许多脊椎动物物种中，存在从幅度调制速率的周期性编码到AM滤波器表示的转换;中脑中的大多数神经元在AM速率的特定范围内响应最佳，即，是带通的。这种转变背后的机制知之甚少。以前的工作表明，兴奋，抑制和可塑性之间的相互作用的基础上选择性的中脑神经元AM率，声音的持续时间和可能的上升时间。本研究提案中概述的具体实验旨在进一步阐明这些突触特性如何被中脑神经元整合，以产生对声音这些时间特征的选择性。

DESCRIPTION (provided by applicant): 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 speech, resides in their temporal structure, and deficits in processing temporal information underlie disorders in speech recognition. An understanding of how the temporal structure of sounds is represented and processed in the nervous system is vital, therefore, 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 they are well suited for neurophysiological investigations of the mechanisms that underlie temporal processing. 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, including pulse duration and rise time, are represented in the brain and the mechanisms that underlie 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. Previous work suggests that interplay between excitation, inhibition and plasticity underlies the selectivity of midbrain neurons for AM rate, sound duration and possibly rise time. The specific experiments outlined in this research proposal are designed to further elucidate how these synaptic properties are integrated by midbrain neurons to generate selectivity for these temporal features of sounds.