Development and plasticity of the neural network for speech motor control

人类的语音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。事实上，语音需要呼吸、喉咙、咽部和口腔运动子系统之间复杂的运动序列，精确到毫秒级。尽管语音在人类互动中扮演着独特的角色，而且它的干扰会使人衰弱，但人们对语音-运动学习及其发展背后的神经机制知之甚少。在我的博士和博士后培训过程中，我研究了在线语音-运动控制中听觉反馈的神经机制。我记录了在健康成年人以及首次在儿童中准确的言语产生过程中，言语运动传出拷贝对听觉反馈的神经抑制效应的重要性(Beal等人，2010、2011、2013)。我还发现，成年人的言语-运动学习与神经活动的变化有关，这两个网络通常与一般运动学习(基底节和前补充运动区)和语音的听觉-运动反馈控制(腹侧运动前、颞叶上后回；比尔等人，正在准备中；Segawa等人，印刷前在线)有关。*我之前的研究结果让我质疑言语-运动学习是如何在童年时期发展起来的，以及它在建立稳定的神经运动程序方面的关键作用，这是在一个人的一生中准确控制言语-运动程序所必需的。*我提议的研究计划将使用行为和多模式定量磁共振成像来调查4-12岁儿童言语运动序列学习神经网络的功能和结构发展。其具体目标是：*1.确定神经运动程序稳定性的发展轨迹语音。2.确定语音听觉-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)神经网络对儿童语音-运动学习的贡献。*这项研究将揭示大脑如何发展和整合听觉-运动信息，以建立语音产生的神经-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是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.**