Development and plasticity of the neural network for speech motor control

人类的言语产生是一种看似简单的运动技能，大多数人认为这是理所当然的。实际上，语音需要在呼吸、喉、咽和口腔子系统之间以毫秒级精度进行复杂的运动排序。尽管言语在人类互动中扮演着独特的角色，以及其中断的破坏性影响，但人们对言语运动学习及其发展的神经机制知之甚少。 在我的博士和博士后培训过程中，我研究了在线言语运动控制中听觉反馈的神经机制。我记录了在健康成年人和儿童的准确言语产生过程中，言语运动传出复制对听觉反馈的神经抑制作用的重要性（比尔等人，2010、2011、2013）。我还发现，成人的言语运动学习与两个网络中的神经活动的变化有关，这两个网络通常与一般运动学习（基底神经节和前补充运动区）和言语的神经运动反馈控制（腹侧前运动区，后上级颞回;比尔等人，在准备中; Segawa等人，在印刷之前在线）。 我以前的研究结果使我质疑语言运动学习在儿童时期是如何发展的，以及它在建立稳定的神经运动程序方面的至关重要的作用，这些程序是在一个人的一生中精确控制语言运动所必需的。 我提议的研究计划将使用行为和多模态定量磁共振成像来研究4-12岁儿童语音运动序列学习神经网络的功能和结构发展。具体目标是： 1.确定言语神经运动程序稳定性的发展轨迹。 2.确定语音的记忆-运动学习的发展轨迹。 3.区分皮质-纹状体（一般运动）和皮质-皮质（听觉运动）神经网络对儿童语言运动学习的贡献。 这项研究将揭示大脑如何发展和整合神经运动信息，以建立言语产生的神经运动程序。它将丰富我们对语音处理的功能和结构神经通路如何在学习和发展过程中获得的理解。

Human speech production is a deceptively simple motor skill that the majority of people take for granted. In actuality, speech requires the complex sequencing of movements among the respiratory, laryngeal, pharyngeal and oromotor subsystems with millisecond level precision. Despite the unique role that speech plays in human interaction, and the debilitating impact of its disruption, little is known about the neural mechanisms underlying speech-motor learning and its development. Over the course of my doctoral and post-doctoral training I investigated the neural mechanisms of auditory feedback in online speech-motor control. I documented the importance of the neural inhibitory effect of speech-motor efference copy on auditory feedback during accurate speech production in healthy adults and, for the first time, in children (Beal et al., 2010, 2011, 2013). I also discovered that adult speech-motor learning is associated with changes in neural activity in both networks typically associated with general motor learning (basal ganglia and pre-supplementary motor area) and auditory-motor feedback control for speech (ventral premotor, posterior superior temporal gyrus; Beal et al., in preparation; Segawa et al., online ahead of print). The results of my previous studies led me to question how speech-motor learning develops in childhood and its critically important role for establishing the stable neuro-motor programs necessary for accurate speech-motor control over one's lifespan. My proposed research program will use behavioral and multi-modal quantitative magnetic resonance imaging to investigate the functional and structural development of the neural network for speech motor sequence learning in children aged 4-12. The specific aims are to: 1. Determine the developmental trajectory of neuro-motor program stability for speech. 2. Determine the developmental trajectory for auditory-motor learning of speech sounds. 3. Differentiate the contributions of the cortico-striatal (general motor) and cortico-cortical (auditory motor) neural networks to speech-motor learning in childhood. This research will reveal how the brain develops and integrates auditory-motor information for establishing neuro-motor programs for speech production. It will enrich our understanding of how the functional and structural neural pathways for speech processing are acquired over the course of learning and development.