Organization and experience-dependence of auditory coding in forebrain

描述（由申请人提供）：处理和感知诸如语音之类的交流声音对人类非常重要，而听觉是两者的关键组成部分。然而，令人惊讶的是，我们对大脑如何转换听觉信号以完成这些复杂任务所知甚少。我们的长期目标是进一步发展一个统一的框架，以了解高级听觉处理以及它如何随着经验和学习而改变。为此，我们建议研究一个阶段，在中央听觉回路中，有一个显着的变化，从简单的，初级样的响应特性复杂的发声敏感性，在听觉前脑的鸣禽。这些动物为提取高级声音处理的一般原理提供了一个很好的模型，因为它们学习与人类相似难度的听觉任务，并且拥有一个辅助这些任务的听觉区域的分层网络，包括相当于初级听觉皮层的鸟类区域L和几个可能相当于带状皮层的次级区域。此外，我们还可以接触到一系列丰富的与行为相关的听觉刺激，比如歌曲。我们最近发现，在场L内，感受场沿着谱轴和时间轴有着惊人的有序组织。我们将问这个组织是否以及如何传播到下一个层次，通过映射这些二级区域的响应选择性电池的歌曲，使用信息理论为基础的技术称为最大信息维度（MID）。我们还将记录对早期（从父亲、伴侣那里）学到的歌曲的反应，以检验另一个假设，即在生命早期学到的声音记忆在这些区域有特殊的表现。同时，我们将通过选择性地标记或关闭这些输入的子集来测试从场L到这些次级区域的输入的解剖学和生理学贡献。最后，武装这些电路的组织的知识，我们将询问是否以及如何他们的感受野组织和歌曲表征的变化后，鸟类学习的行为辨别任务，强烈关注他们的注意力在任何频谱或时间方面的歌曲，两个关键参数映射在字段L，并在正常和受损的听觉处理的关键。

DESCRIPTION (provided by applicant): Processing and perception of communication sounds such as speech are enormously important to humans, and hearing is a critical component of both. Yet we know surprisingly little about how the brain transforms auditory signals to accomplish these complex tasks. Our long-term objective is to further the development of a unified framework for understanding high-level auditory processing and how it changes, for good or ill, with experience and learning. To this end, we propose to study a stage in a central auditory circuit where there is a remarkable change from simple, primary-like response properties to complex vocalization-sensitivity, in the auditory forebrain of songbirds. These animals provide an excellent model for extracting general principles of higher-level sound processing, because they learn auditory tasks of similar difficulty to humans, and possess a hierarchical network of auditory areas that sub serve these tasks, including the avian equivalent of primary auditory cortex, field L, and several secondary areas that are the likely equivalent of belt cortex. Moreover, we have access to a rich set of auditory stimuli of behavioral relevance, songs. We recently found that within field L there is a strikingly orderly organization of receptiv fields, along spectral and temporal axes. We will ask whether and how this organization propagates to the next level, by mapping the response selectivity of these secondary areas to batteries of songs, using an information theory-based technique called maximally informative dimensions (MID). We will also record responses to songs learned earlier (from father, mate) to examine the additional hypothesis that sound memories learned early in life have a special representation in such areas. In parallel, we will test the anatomical and physiological contribution of the inputs from field L to these secondary areas, by selectively labeling or turnin off subsets of these inputs. Finally, armed with the knowledge of these circuits' organization, we will ask whether and how their receptive field organization and song representations change after birds learn a behavioral discrimination task that strongly focuses their attention on either spectral or temporal aspects of song, two key parameters mapped in field L, and critical both in normal and impaired auditory processing.