Cell Survival in a Neural Circuit for Learning

描述（由申请人提供）：像人类一样，鸣禽在早期发育的敏感时期学习其物种用于交流的声音。在许多鸣禽物种中，只有雄性才学会唱歌，这种行为性别差异的一个显著后果是，成年雄性大脑中控制歌曲的区域很突出，而成年雌性的尺寸缩小（或不存在）。在斑胸草雀中，一些发声控制区域最初在两性中发育。然而，在少年阶段的歌曲学习这些地区表现出大量的神经元死亡的女性，和增长与很少的神经元死亡的男性。我们的工作假设是，歌曲学习的质量和歌曲区域的形态发育受到幼鸟练习发声模式的影响。使用依赖性机制在运动学习、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有充分的先例。然而，使用依赖机制在声乐学习（人类或鸣禽）的贡献从来没有得到评估，部分原因是难以衡量的行为，是自愿的，并发生在高水平的发展过程中。然而，通过使用事件触发记录系统（允许连续监测单个鸟类的声音输出），我们已经证明，正在学习唱歌的幼鸟的每日歌曲产量明显高于成年鸟。在歌曲制作的个体差异也是最大的青少年，和鸟类唱更多的青少年有一个更高质量的歌曲作为成年人。因此，鸣禽声乐学习似乎涉及一个“实践驱动”的组成部分，这可能与成熟因素相互作用，影响神经发育，并确定成人声乐模式的质量。在此背景下，将检查几个基因产物，以建立唱歌和1之间的联系。（2）实践的影响;驱动歌曲区域生长的机制，以及3.）影响青少年排练歌曲的动机系统。我们将在斑胸草雀中研究的所有基因系统都与它们的人类对应物具有高度的同源性，因此我们对它们在鸣禽中的作用的了解可能对人类大脑发育和声音学习具有功能性意义。

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.