Collaborative Research: Defining the neurobiological requirements for vocal learning in birds

蜂鸟、鸣禽和鹦鹉从成年人那里学习发声，就像人类婴儿通过模仿父母的讲话来学习说话一样。这种能力为人类如何获得言语和语言提供了基础，但大脑如何实现这一目标尚不清楚。利用一系列强大的技术，这个合作项目将检查控制蜂鸟和鸣禽发声的大脑回路的解剖学、电学和分子特性，并将它们相互比较，并与之前的人类研究进行比较。了解这些不同的生物如何进化大脑回路来完成类似的目标，将揭示对声音学习系统基本特性的见解。传统的实验动物不能使用，因为它们缺乏声音学习；因此，使用发声学习鸟是至关重要的。该项目将为高中生、本科生和研究生提供多种研究技术方面的培训，重点关注未被充分代表的群体。它还将促进广泛传播与科学和养护工作有关的发现和外联活动。该项目还与一个国际联盟（由巴西政府资助）进行了整合，该联盟负责对热带鸟类的多样性进行编目和特征描述，包括整合博物馆藏品，生成基因组序列，以及检查与声乐学习进化相关的大脑标本。这些活动将促进美国和巴西教师和学生之间的互动，同时通过实地考察、实地考察和研讨会促进分子和组织学方法的培训。鸣禽的发声控制系统对鸣叫和学习至关重要，并在解剖学、电生理学和分子生物学上得到了很好的表征。然而，在其他鸟类声乐学习者的类似领域的知识是有限的。最近的系统基因组学研究表明，蜂鸟独立于鸣禽进化出了声音学习能力；因此，比较它们的声音控制系统将揭示这种特征可能根本需要的趋同进化特征。研究人员将使用通道追踪来确定蜂鸟的声音控制区域是如何连接的，在体外电生理记录来确定蜂鸟和鸣禽的声音区域的内在神经元特性，以及原位杂交来识别声核的分子标记。解剖学、生理学和分子专门化的共同证据将指向一些趋同的特征，这些特征代表了可能与人类共享的声音学习系统的普遍特性。另一种差异可能表明，多回路和细胞/分子结构可以支持声音学习。研究结果将为声乐学习的进化起源和限制以及相关途径提供新的线索，从而深入了解声乐学习的基本要求。

Hummingbirds, songbirds and parrots learn their vocalizations from adults, just like human infants learn to speak by imitating their parents' speech. This capacity provides the basis for how humans acquire speech and language, yet how the brain achieves this goal is unknown. Using an array of powerful techniques, this collaborative project will examine the anatomical, electrical, and molecular properties of brain circuits that control vocalizations in hummingbirds and songbirds, comparing them with each other and with prior human studies. Understanding how these different organisms evolved brain circuits to accomplish similar goals will reveal insights into fundamental properties of vocal learning systems. Traditional lab animals cannot be used as they lack vocal learning; hence, the use of vocal learner birds is critical. The project will provide training in multiple research techniques to high school, undergraduate, and graduate students, emphasizing underrepresented groups. It will also promote broad dissemination of findings and outreach activities, related to both scientific and conservation efforts. The project is also integrated with an International Consortium (funded by the Brazilian Government) for cataloguing and characterizing the diversity of tropical birds, including integration of Museum collections, generation of genome sequences, and examination of brain specimens relevant to the evolution of vocal learning. These activities will enable interactions between US and Brazilian faculty and students, while promoting training in molecular and histological methods through site visits, field trips, and workshops.The vocal control system of songbirds is critical for song production and learning, and is well characterized anatomically, electrophysiologically, and molecularly. However, knowledge of the analogous areas in other avian vocal learners is limited. Recent phylogenomics efforts reveal that hummingbirds evolved vocal learning independently of songbirds; thus, comparing their vocal control systems will reveal convergently evolved features that may be fundamentally required for this trait. The investigators will use tract-tracing to determine how vocal control areas are connected in hummingbirds, in vitro electrophysiological recordings to determine intrinsic neuronal properties of vocal areas in hummingbirds and songbirds, and in situ hybridization to identify molecular markers of vocal nuclei. Evidence of shared anatomical, physiological and molecular specializations will point to convergent features representing possible universal properties of vocal learning systems that may also be shared with humans. Alternatively, differences would suggest that multiple circuit and cellular/molecular architectures can subserve vocal learning. Outcomes will provide novel clues as to evolutionary origins and constraints of vocal learning and associated pathways, leading to insights into fundamental requirements of vocal learning.