Neural mechanisms underlying vocal learning in zebra finches

学习一项运动技能通常需要将通过观察形成的内部神经模板转化为一系列运动命令。为了达到理想的动作，有必要进行多次练习，并将表现与模板进行比较。例如，学习发球需要观察老师，练习发球，在练习中发现错误。运动技能学习过程的神经机制尚不清楚。我在斑胸草雀身上解决了这个问题，斑胸草雀是一种通过观察学习获得歌声的鸣禽：斑胸草雀听导师的话，形成一个神经歌唱模板，将这个模板整合到它们的运动程序中，并将它们正在进行的歌唱表演与模板进行比较。斑胸草雀具有相互关联的专用神经通路，用于听觉处理、运动产生和歌曲学习，因此特别适合研究感觉信息如何在神经元水平上转化为运动表现。为了探索运动学习过程中神经回路之间的相互作用，测量这些回路在行为过程中的突触输入和输出是很重要的。细胞内记录使我们能够从单个细胞的角度监测网络活动，是测量网络内部和网络之间潜在神经动力学的理想技术。细胞内微驱动器代表了一种新的工具来测量突触输入到单个细胞的行为。在我的博士后期间，我帮助开发了细胞内微驱动，并用它来研究成年和幼年斑胸草雀在唱歌和听的过程中运动前核的感觉运动整合。在未来，我计划在不同发育阶段对自由行为的斑胸草雀进行细胞内记录，包括在高阶听觉区和负责运动产生和学习的区域。这些实验将揭示模板形成过程中神经元的突触特征，并阐明练习所带来的性能改善是如何在细胞水平上进行编码的。我的研究计划的具体目的是1)研究高阶听觉区域如何代表歌曲模板，以阐明模板如何在歌曲排练期间整合到运动电路中；2)探索运动路径发送的输出信号如何根据目标模板进行严格评估，以提高运动性能。

Learning a motor skill often involves transforming an internal neural template that has been shaped by observation into a series of motor commands. To reach the desired movement, it is necessary to practice many times and compare the performance to the template. Learning to serve a tennis ball, for instance, involves observing a teacher, rehearsing your serve and recognizing your mistakes while practicing. The neural mechanisms underlying the process of motor skill learning are not well understood. I address this issue in the zebra finch, a songbird that acquires its song via observational learning: zebra finches listen to their tutor to form a neural song template, integrate this template into their motor program, and compare their ongoing song performance to the template. Zebra finches have interconnected, dedicated neural pathways for auditory processing, motor production and song learning and are thus particularly well suited for studying how sensory information is translated into motor performance on a neuronal level. To explore interactions between neural circuits during motor learning it is important to measure the synaptic inputs and outputs of these circuits during behavior. Intracellular recordings enable us to monitor network activity from the perspective of a single cell and are the ideal technique to measure the underlying neural dynamics within and across networks. The intracellular microdrive represents a novel tool to measure synaptic inputs onto single cells during behavior. During my postdoc I helped to develop the intracellular microdrive and used it to investigate sensorimotor integration in the premotor nucleus of adult and juvenile zebra finches during singing and listening. In the future I plan to perform intracellular recordings in freely behaving zebra finches at various developmental stages both in higher-order auditory areas and areas responsible for motor production and learning. These experiments will reveal the synaptic profile of neurons during the formation of the template and clarify how the performance improvements that practice affords are encoded at the cellular level. The specific aims of my research proposal are 1) to investigate how higher-order auditory areas represent the song template in order to elucidate how the template is integrated into the motor circuit during song rehearsal and 2) to explore how the output signal sent by the motor pathway is critically evaluated against the target template to improve motor performance.