Unraveling posture control in severe cerebral palsy.

脑性瘫痪(CP)的绝大多数研究涉及具有站立和行走能力的儿童。相比之下，患有严重脑瘫的儿童，他们没有行走能力，通常被排除在基于活动的研究之外，或者以非常简单或非客观的方式进行研究。本项目将重点了解重度脑瘫儿童躯干姿势控制的复杂任务。躯干姿势控制几乎是所有运动活动的基础，包括说话、进食和社交。该项目以一种创新的方式使用控制系统工程来确定患有严重脑瘫的个别儿童的哪些神经过程是完整的、延迟的或缺失的。此外，虽然有为有站立能力的成年人提供的姿势模型，但没有为缺乏独立坐着的个人或患有CP的儿童提供的模型。研究人员将开发和验证在姿势控制中量化特定神经系统的模型。这些模型有助于确定CP儿童在试图控制他们的平衡时所使用的潜在机制。模型的开发、改进和测试将是临床工程中的一大进步，因为模型参数的量化，如关节刚度和神经时延，将对临床实践产生直接和基本的影响。与该项目相关的教育活动将吸引高中、本科生和研究生中有无CP的学生参与。除了学习姿势控制外，学生还将学习建模和控制系统。最后，学生将参与创建和测试一种独特的传播工具--“SIMCP”。在“SIM CP”中，发育中的儿童和成人通常可以尝试控制自己的姿势，同时受到计算机模拟的限制，以适应与CP类似的对运动结果的挑战。这项研究项目将通过结合工程学、参数建模和临床儿科学来研究严重脑瘫儿童的姿势控制，并通过指导学生和创造新的传播工具来增加影响。由于闭环姿势控制的内在复杂性，很难识别健康姿势摇摆背后的神经过程。这一困难在患有严重脑瘫的儿童中加剧，他们缺乏独立的坐着，也可能有不正常的语调或缺乏语言交流。本项目通过利用控制工程学来探索中重度脑瘫儿童的姿势系统，从而克服了这些障碍。研究计划是按照三个目标组织的。第一个目标是通过收集丰富的姿势行为实验数据集来表征姿势系统和学习潜力。参与者坐在一个铰接式长凳上，后备箱系统可调节，与地面倾斜同步移动，分辨率和精度都很高。该支撑件在垂直垂直对齐中稳定躯干的特定节段，同时要求在支承节段上方进行静态、主动和反应性姿势控制。姿势反应将由定制的外部刺激引起：正弦波、伪随机波形和一种新的以坐姿为参照的条件来检查运动学习。数据将通过两个不同级别的干线支持进行收集：最低级别存在干线控制，而较低级别则挑战控制。第二个目标是开发实验有效的姿势系统参数模型，解释从大约0.04到1.5赫兹的频率范围内的摇摆数据。姿态模型将识别潜在的系统和控制机制，如神经时滞、感觉运动噪声、感觉到运动的转换、关节刚度和阻尼以及控制参数的适应。将测试不同的模型假设(基于现有的电机控制研究)。第三个目标是使用相同的实验和建模技术比较15名患有中到重度CP(粗大运动功能分级等级IV和V级)的6至17岁儿童和年龄匹配的对照组的结果。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The vast majority of research in cerebral palsy (CP) involves children who have the ability to stand and walk. In contrast, children with severe CP, who do not have the ability to walk, are typically excluded from activity-based research or are studied in very simplistic or nonobjective ways. This project will focus on understanding the complex task of trunk posture control in children with severe CP. Trunk posture control underlies nearly all motor activities, including speech, eating, and socialization. This project uses control systems engineering in an innovative way to determine which neural processes are intact, delayed, or absent in individual children with severe CP. Furthermore, while posture models exist for adults who have the ability to stand, no model exists for individuals who lack independent sitting or for children with CP. The researchers will develop and validate models that quantify specific neural systems in posture control. These models help identify underlying mechanisms used by children with CP when attempting to control their balance. The development, refinement, and testing of models will be a major advance in clinical engineering, in that the quantification of model parameters, e.g., joint stiffness and neural time delay, will have immediate and fundamental implications on clinical practice. Educational activities associated with this project will engage students with and without CP who are in high school, undergraduate, and graduate school. In addition to learning about posture control, students will learn about modeling and control systems. Finally, students will be engaged in creating and testing a unique dissemination tool, "sim CP." In "sim CP," typically developing children and adults can attempt to control their posture while constrained by the computer simulation to adjust to CP-like challenges on motor outcomes. Together, this research project will catalyze the field by combining engineering, parametric modeling, and clinical pediatrics to investigate posture control in children with severe CP with the added impact of mentoring students and creating novel dissemination tools.Due to the inherent complexity of closed loop posture control, it is difficult to identify neural processes underlying healthy posture sway. This difficulty is exacerbated in children with severe CP who lack independent sitting, and who may also have abnormal tone or lack of verbal communication. This project overcomes these barriers by leveraging controls engineering to probe the posture system of children with moderate-to-severe CP. The Research Plan is organized under three objectives. The first objective is to characterize the posture system and potential for learning by collecting a rich experimental data set of posture behavior. Participants sit on an articulating bench with an adjustable trunk system that moves synchronously with surface tilts with high resolution and accuracy. The support stabilizes specific segments of the trunk in vertical upright alignment while requiring static, active and reactive posture control above the supported segments. Posture responses will be evoked with custom external stimuli: sine waves, pseudorandom waveforms, and a novel sitting sway-referenced condition to examine motor learning. Data will be collected with two different levels of trunk support: the lowest level where trunk control is present and one level lower where control is challenged. The second objective is to develop experimentally-valid parametric models of the posture system that explain sway data across frequencies from approximately 0.04 to 1.5 Hz. The posture model will identify underlying systems and control mechanisms, such as neural time delays, sensorimotor noise, sensory-to-motor transformations, joint stiffness and damping, and adaptation of control parameters. Different model assumptions (based on existing motor control research) will be tested. The third objective is to compare results in 15 children, ages 6 to 17 years old with moderate to severe CP (Gross Motor Function Classification Scale levels IV & V), to age-matched controls using the same experimental and modeling techniques.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.