Inhibitory Circuits and Their Role in the Analysis of Complex Sounds

复杂的生物声音在许多动物的交流中尤为重要，对人类来说也是如此。这些声音包含了光谱（声音波长或音高）和时间（模式）领域的信息。这些特性被编码在听神经神经元的反应中，听神经将信号从耳朵传递到大脑。编码信号在脑干和中脑的两个重要中继中心进一步转换，因为兴奋和抑制过程以特定的方式聚集在特定的神经元上。这些中心的一些神经元在对同一物种动物的特定光谱和时间特征的反应中具有高度选择性。选择性是由神经元输入到这些细胞的兴奋和抑制的组合产生的。本项目以青蛙为模型系统，以其高度专业化的叫声来探索听觉网络中刺激选择性的机制。电生理学和药理学的结合被用于一种新的方法来阐明不仅仅是一种，而是两种不同的抑制化合物，称为GABA和甘氨酸，如何塑造这些反应，并在不同阶段提高系统的刺激选择性。结果将增加我们对时间和频率滤波器如何在听觉系统中构建和相互作用的认识，并增强我们对复杂声音识别背后的生物和计算机制的一般理解。其影响将超越感觉神经生物学，扩展到交流行为研究、人工语音工程和交流识别系统。

9421180 Hall JC Complex biological sounds are particularly important in communication for many animals, as well as speech for humans. Such sounds contain information in both spectral (sound wavelength, or pitch) and temporal (patterning) domains. These properties are encoded in responses of neurons in the auditory nerve carrying signals from the ear to the brain. The coded signals are further transformed in two important relay centers in the brainstem and in the midbrain, as excitatory and inhibitory processes converge in particular ways on particular neurons. Some of the neurons in these centers are highly selective in their responses to particular spectral and temporal features of vocalizations by animals of the same species. Selectivity is created by combinations of excitation and inhibition from neuronal inputs to these cells. This project uses frogs, with their highly specialized calls, as a model system for exploring the mechanisms of stimulus selectivity in auditory networks. A combination of electrophysiology and pharmacology is used in a novel approach to clarify how not just one, but two different inhibitory compounds, called GABA and glycine, shape these responses and sharpen the stimulus selectivity of the system in the different stages. Results will add to our knowledge of how time and frequency filters are constructed and interact in the auditory system, and enhance our general understanding of the biological and computational mechanisms that underlie complex sound recognition. The impact will extend beyond sensory neurobiology to studies of communication behavior, to engineering of artificial speech, and to recognition systems for communications.