Neural processing and perception of complex sounds

描述（由申请人提供）：本研究的长期目标是加深我们对复杂声音加工的机制理解，并将皮层神经表征与听觉感知联系起来。为此，我建议研究具有丰富声音交流行为的物种——鸣禽的听觉前脑——的中央听觉回路中复杂的声音处理。鸣禽为研究高级声音处理的一般原理提供了一个很好的模型，因为它们面临着复杂的听觉任务。此外，它们还拥有一个层次分明的听觉区域网络，为这些任务提供支持，包括鸟类的初级听觉皮层，field l。我最近发现，在field中，有一个简单的时间和频谱接受场的有序组织。这种有组织的声音特征表示为研究复杂声音的皮层处理提供了一个框架。在提出的实验中，我将进一步研究单个神经元水平上的表征，通过探测自然发声刺激和映射非线性接受野，使用一种基于信息理论的技术，称为最大信息维度。为了开始解决产生表征的电路机制，我将再次绘制场L的接受野图，同时选择性地使场L的不同子区域失活。最后，我将通过在鸟类执行操作性歌曲辨别任务时使场L的子区域失活，来测试具有不同训练特性的场L子区域对复杂声音感知的不同贡献的假设。本研究的结果不仅将进一步加深我们对光谱颞叶感受野如何通过神经回路产生及其与感知的关系的基本理解，而且对听觉障碍的治疗也将具有重要意义。

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. PUBLIC HEALTH RELEVANCE: Basic understanding of neural processing of complex communication signals is crucial for devising strategies to cope with hearing impairments in humans. The proposed study, which uses a tractable animal model with rich vocal communication and learning behavior, has potential to provide novel insights into the general principles of complex sound processing. The outcome will have implications for speech perception, hearing dysfunction, and many other diseases in which auditory dysfunction has been implicated.