Cell Survival in a Neural Circuit for Learning

描述(申请人提供)：像人类一样，鸣禽在早期发育的敏感时期学习它们物种用来交流的声音。在许多鸣禽物种中，只有雄鸟才会学习唱歌，这种行为性别差异的一个显著后果是，成年雄鸟控制歌唱的大脑区域突出，而成年雌性鸣鸟的大脑区域缩小(或缺失)。在斑马雀中，一些发声控制区最初在两性中都会发育。然而，在歌曲学习的幼年阶段，这些区域在雌性中显示出大量的神经元死亡，在雄性中显示出较少的神经元死亡。我们的工作假设是，歌唱学习的质量和歌唱区域的形态发育受到幼鸟练习发声模式的频率的影响。依赖使用的机制在运动学习、神经生长和可塑性中的作用在包括人类在内的其他动物中已经有了大量的先例。然而，使用依赖机制在发声学习(人类或鸣禽)中的贡献从未被评估过，部分原因是很难衡量一种自愿的行为，这种行为发生在发育过程中的高水平。然而，通过使用事件触发的记录系统(允许持续监测单个鸟类的声音输出)，我们已经表明，正在学习唱歌的幼鸟每天的歌声产量明显高于成年鸟。在青少年中，歌唱的个体差异也最大，在青少年时期唱歌更多的鸟类在成年后会有更高质量的歌曲。因此，鸣禽的发声学习似乎涉及到一个“练习驱动”的成分，它可能与成熟因素相互作用，影响神经发育，并决定成人发声模式的质量。将在此背景下研究几种基因产品，以建立歌唱和1之间的联系。储存练习的效果，2.)推动宋代地区发展的机制，以及3.)影响青少年排练歌曲的动机系统。我们将在斑马雀身上研究的所有基因系统都显示出与人类同行的高度同源性，所以我们所了解到的斑马雀在鸣禽中的作用可能会对人类大脑发育和发声学习产生功能影响。

DESCRIPTION (provided by applicant): Like humans, songbirds learn the sounds used by their species to communicate during a sensitive period of early development. In many songbird species only males learn to sing and a striking consequence of this behavioral sex difference is that the brain regions for song control are prominent in adult males and diminished in size (or absent) in adult females. In the zebra finch, some vocal control regions initially develop in both sexes. However, during the juvenile phase of song learning these regions show substantial neuron death in females, and growth with little neuron death in males. Our working hypothesis is that the quality of song learning and the morphological development of song regions are influenced by how often juvenile birds practice their vocal pattern. A role for use-dependent mechanisms in motor learning and neural growth and plasticity has ample precedent in other animals, including humans. However, the contribution of use-dependent mechanisms in vocal learning (human or songbird) has never been evaluated, partly because of the difficulty of measuring a behavior that is voluntary and that occurs at high levels over the course of development. However, with the use of an event-triggered recording system (which allows continuous monitoring of the vocal output of individual birds), we have shown that daily song production is significantly greater in juvenile birds that are learning to sing than in adults. Individual differences in song production are also greatest in juveniles, and birds that sing more as juveniles have a higher quality song as adults. Thus, songbird vocal learning appears to involve a 'practice-driven' component, which may interact with maturational factors to influence neural development and determine the quality of the adult vocal pattern. Several gene products will be examined in this context to establish links between singing and 1.) storage of the effects of practice, 2.) mechanisms that drive the growth of song regions, and 3.) motivational systems that influence rehearsal of song by juveniles. All of the gene systems that we will study in zebra finches show a high degree of homology to their human counterparts, so what we learn about their role in songbirds may have functional implications for human brain development and vocal learning.