Bottjer S W, Arnold A P
Department of Biology, University of Southern California, Los Angeles 90089-2520, USA.
Annu Rev Neurosci. 1997;20:459-81. doi: 10.1146/annurev.neuro.20.1.459.
The neural substrate underlying learned vocal behavior in songbirds provides a textbook illustration of anatomical localization of function for a complex learned behavior in vertebrates. The song-control system has become an important model for studying neural systems related to learning, behavior, and development. The song system of zebra finches is characterized by a heightened capacity for both neural and behavioral change during development and has taught us valuable information regarding sensitive periods, rearrangement of synaptic connections, topographic specificity, cell death and neurogenesis, experience-dependent neural plasticity, and sexual differentiation. The song system differs in some interesting ways from some well-studied mammalian model systems and thus offers fresh perspectives on specific theoretical issues. In this highly selective review, we concentrate on two major questions: What are the developmental changes in the song system responsible for song learning and the restriction of learning to a sensitive period, and what factors explain the highly sexually dimorphic development of this system? We discuss the important role of sex steroid hormones and of neurotrophins in creating a male-typical neural song circuit (which can learn to produce complex vocalizations) instead of a reduced, female-typical song circuit that does not produce learned song.
鸣禽习得性发声行为背后的神经基质为脊椎动物复杂习得行为的功能解剖定位提供了一个典型例证。鸣唱控制系统已成为研究与学习、行为及发育相关神经系统的重要模型。斑胸草雀的鸣唱系统特点是在发育过程中神经和行为变化能力增强，它为我们提供了有关敏感期、突触连接重排、拓扑特异性、细胞死亡与神经发生、经验依赖性神经可塑性以及性别分化等方面的宝贵信息。鸣唱系统在一些有趣的方面与某些经过充分研究的哺乳动物模型系统不同，因此为特定理论问题提供了新的视角。在这篇极具选择性的综述中，我们聚焦于两个主要问题：鸣唱系统中负责鸣唱学习以及将学习限制在敏感期的发育变化是什么，以及哪些因素解释了该系统高度两性异形的发育过程？我们讨论了性类固醇激素和神经营养因子在构建典型雄性神经鸣唱回路（能够学习发出复杂叫声）而非发育不全的、不会发出习得性鸣唱的典型雌性鸣唱回路中所起的重要作用。
