Multiple Disciplinary Collaborative Research: Evolution of Brain Structures for Vocal Learning in Birds

贾维斯。发声学习是幼年动物学习模仿父母或导师发出的声音的过程。这种罕见的特征只在人类、鲸鱼、海豚、蝙蝠和3种鸟类（蜂鸟、鹦鹉和鸣禽）中发现。该项目的目标是识别和描述蜂鸟控制声音交流的大脑区域，以及测试没有声音学习的鸟类（如鸡和鸽子）的大脑是否包含类似的结构。使用的主要方法是分析神经元细胞放电时在大脑中表达的基因。利用一种称为原位杂交的分子技术，人们可以确定参与感知和产生发声的确切脑细胞。通过比较听觉动物和发声动物，人们可以绘制出控制习得发声的大脑区域的高分辨率地图。语言习得，无论是在言语产生还是语义方面，都是人类经验的一个基本方面，并依赖于声乐学习。为什么有发声能力的动物如此之少呢？只有这些动物有必要的大脑结构和连接吗？如果是这样，这些结构是什么，它们是如何在进化过程中出现的？通过解决这些问题，这项研究可能有助于揭示声音学习所需的大脑机制，并有可能帮助理解人类如何学习语言。该结果也为研究其他动物群体习得的声音交流的神经生物学提供了一个框架。如果声音学习的进化受到很强的表观遗传限制，那么人类、鲸目动物和蝙蝠也有可能进化出类似的大脑结构。另一种说法是，用于发声学习的大脑区域可能是作为一种特殊的结构进化而来的，这种结构存在于不能发声的祖先身上。这个项目的结果有望对这些问题提供相当大的启示。

Jarvis. Lay AbstractVocal learning is the process by which young animals learn to imitate the vocal sounds made by their parents or a tutor. This rare trait has only been found in humans, whales, dolphins, bats and 3 groups of birds (hummingbirds, parrots and songbirds). The goal of this project is to identify and characterize the brain areas that control vocal communication in hummingbirds, as well as test whether the brains of birds that do not have vocal learning, such as chicken and pigeons, contain similar structures. The main method used is analysis of a gene that is expressed in the brain when neuronal cells fire. Utilizing a molecular technique called in situ hybridization, one can determine the exact brain cells that are involved in the perception and production of vocalizations. By comparing hearing and vocalizing animals, one can then generate high-resolution maps of brain areas that control the production of learned vocalizations.Language acquisition, both in terms of speech production and semantics, is a fundamental aspect of the human experience and depends on vocal learning. Why is it though that so few animals have vocal learning? Do only these animals have the necessary brain structures and connections? If so, what are these structures, and how did they arise during evolution? By addressing such questions, this study may help reveal what are the brain mechanisms required for vocal learning, and potentially help understand how humans learn speech. The results should also provide a framework for studying the neurobiology of learned vocal communication in other animal groups. If the evolution of vocal learning is under strong epigenetic constraints, it is possible that humans, cetaceans and bats have also evolved similar brain structures. Alternatively, brain areas for vocal learning may have evolved as a specialization of structures present in a vocal non-learning ancestor. Results from this project are expected to throw considerable light on these questions.