Neural processing and perception of complex sounds

描述(由申请人提供)：拟议研究的长期目标是加深我们对复杂声音处理的机械理解，并将皮质神经表征与听觉感知联系起来。为此，我建议研究一种具有丰富声音交流行为的物种--鸣鸟的听觉前脑--的中央听觉回路中复杂的声音处理。鸣禽面临着复杂的听觉任务，为研究高级声音处理的一般原理提供了一个极好的模型。此外，它们拥有一个为这些任务提供服务的听觉区域的分层网络，包括鸟类的初级听觉皮质L场。我最近发现，在场中，简单的时间和光谱感受场有一个有序的组织。声音特征的这种有组织的表示提供了用于研究复杂声音的皮层处理的框架。在拟议的实验中，我将通过使用自然发声刺激的探测和非线性感受场的映射，使用一种基于信息论的最大信息维度技术，进一步研究单个神经元水平上的表征。为了开始解决产生表征的电路机制，我将再次映射L场中的感受野，同时选择性地灭活场L的不同亚区。最后，我将检验这样一种假设，即当鸟类执行可操作的鸣叫辨别任务时，场L不同发声性质的亚区通过灭活L场的亚区而对复杂声音的感知有不同的贡献。这项研究的结果不仅将加深我们对频谱时间感受场如何通过神经回路产生以及它们如何与知觉相关的基本理解，而且还将对治疗听觉障碍具有重要意义。

DESCRIPTION (provided by applicant): The long-term objective of the proposed study is to deepen our mechanistic understanding of complex sound processing and to relate cortical neural representations to auditory perception. To this end, I propose to study complex sound processing in a central auditory circuit of a species with rich vocal communication behavior - the auditory forebrain of songbirds. Songbirds provide an excellent model for studying general principles of higher-level sound processing, because of the complex auditory tasks they face. Moreover, they possess a hierarchical network of auditory areas that subserve these tasks, including the avian equivalent of primary auditory cortex, field L. I recently found that in field there is an orderly organization of simple temporal and spectral receptive fields. This organized representation of sound features provides a framework for investigating cortical processing of complex sounds. In the proposed experiments, I will further investigate the representation at the single neuron level, by probing with natural vocalization stimuli and by mapping nonlinear receptive fields, using an information theory-based technique called maximally informative dimensions. To begin to address the circuit mechanisms that give rise to the representation, I will then map the receptive fields in field L again while selectively inactivating different subregions of field L. Finally, I will test the hypothesis that field L subregions with different tning properties differentially contribute to perception of complex sounds, by inactivating subregions of field L while birds perform operant song discrimination tasks. The outcome of the proposed study will not only further our basic understanding of how spectrotemporal receptive field arise through neural circuits and how they relate to perception, but will also have important implications for treating auditory disorders.