Posture in oromotor control

姿势是一种基本的运动行为，是自主运动的前兆（Ting, 2007）。即使是基本的动作，如伸手，也需要控制头部和躯干的姿势（Soechting & Flanders, 1991）。在对姿势达成普遍理解的过程中，部分问题在于，文献几乎只关注头部、躯干和四肢。目前尚不清楚这些大型结构的姿势控制范式是否同样适用于身体的其他区域。这项拟议的研究旨在提高我们对口腔部位姿势的理解，口腔是呼吸、进食、吞咽、面部表情和语言等重要功能的宿主。例如，尽管研究重力对姿势的影响已有很长的传统（Ivanenko & Gurfinkel, 2008），但在运动系统中，重力对姿势的影响在很大程度上被忽视了。宇航员克里斯·哈德菲尔德从远征35号太空任务中返回后报告说：“我能感觉到我的嘴唇和舌头的重量，不得不改变我说话的方式。我没有意识到我已经学会了用没有重量的舌头说话。”(https://www.npr.org/2013/05/18/184821421/)。通过明确地将姿态建模为运动行为的基本基础，我们正在建立一个新的研究方向，有望进一步了解运动控制，以及一般的姿势。我们建议在两个阶段进行一系列的三组研究。第一阶段的研究将涉及计算机模拟和现有数据集的分析，这些研究可以在实验室设施因COVID-19而关闭时远程进行。二期研究包括使用口内视频、超声成像和肌电图的实验室实验。该研究将重点放在三个研究问题上。首先，口腔姿势如何受到外部扰动的影响？我们研究了重力的变化是如何系统性地改变宇航员的语言的，以及舌头的姿势是如何适应咬块扰动降低舌头和下巴的。其次，口腔姿势是否“即使在没有运动的情况下也保持活跃”（Martin, 1977）？我们研究了舌头和软腭的姿势行为，后者在呼吸、吞咽和说话时负责打开和关闭鼻腔。最后，口腔姿势如何受到同步言语运动的内部扰动的影响？我们研究了表达姿势（如微笑）如何对言语中相互冲突的短暂嘴唇运动做出反应。除了在生物医学工程、运动控制、感觉-运动整合和认知/意识的具体化模型等领域推进理论外，我们改进的人类运动系统模型将影响手术计划和康复、机器人、语言教学和学习、计算机动画以及吞咽障碍和语言发展和衰退的临床干预等应用领域。

Posture is a fundamental motor behaviour, and is a precursor to voluntary movements (Ting, 2007). Even basic movements such as reaching require control of head and trunk posture (Soechting & Flanders, 1991). Part of the problem in arriving at a universal understanding of posture is that the literature has focused almost exclusively on the head, trunk and limbs. It is unknown whether the control paradigms that have been proposed for posture of these large structures apply equally to other regions of the body. The proposed research aims to improve our understanding of posture in the oral region, host to such vital functions as breathing, feeding, swallowing, facial expression and speech. For example, although there has been a long tradition of investigating the effects of gravity on posture (Ivanenko & Gurfinkel, 2008), gravitational effects on posture in oromotor systems has been largely overlooked. After returning from the Expedition 35 space mission, astronaut Chris Hadfield reported: "I could feel the weight of my lips and tongue and had to change how I was talking. I didn't realize I had learned to talk with a weightless tongue." (https://www.npr.org/2013/05/18/184821421/). By explicitly modeling posture as a fundamental basis of oromotor behaviour, we are establishing a new research direction that promises to further our understanding of oromotor control, and of posture in general. We propose a series of three study sets across two phases. Phase 1 studies will involve computer simulations and analyses of existing datasets, which can be carried out remotely while laboratory facilities are closed due to COVID-19. Phase 2 studies include laboratory experiments using intraoral video, ultrasound imaging and electromyography. The study sets focus on three research questions. Firstly, how are oral postures affected by external perturbations? We investigate how changes in gravity systematically change the speech of astronauts, and how tongue posture adapts in response to bite block perturbation lowering the tongue and jaw. Secondly, do oral postures remain "active [even] in the absence of movement" (Martin, 1977)? We examine postural behaviours of the tongue and velum, the latter of which is responsible for opening and closing the nasal cavity during breathing, swallowing, and speech. Lastly, how are oral postures affected by internal perturbations from synchronous speech movements? We investigate how expressive postures (e.g., smiling) respond to conflicting transient lip movements from speech. In addition to advancing theory in areas such as biomedical engineering, motor control, sensory-motor integration and embodied models of cognition/consciousness, our improved models of the human oromotor system will impact application areas such as surgical planning and rehabilitation, robotics, language teaching and learning, computer animation and clinical intervention in swallowing disorders and language development and decline.