Unraveling posture control in severe cerebral palsy.

绝大多数关于脑瘫（CP）的研究都涉及有站立和行走能力的儿童。相比之下，患有严重CP的儿童，没有行走能力，通常被排除在以活动为基础的研究之外，或者以非常简单或非客观的方式进行研究。本项目将重点了解严重CP儿童躯干姿势控制的复杂任务。躯干姿势控制是几乎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CP的儿童个体中哪些神经过程是完整的、延迟的或缺失的。此外，虽然有针对能够站立的成年人的姿势模型，但没有针对缺乏独立坐下的个体或患有CP的儿童的模型。研究人员将开发和验证量化姿势控制中特定神经系统的模型。这些模型有助于识别患有CP的儿童在试图控制平衡时使用的潜在机制。模型的开发、完善和测试将是临床工程学的一个重大进步，因为模型参数的量化，例如关节刚度和神经时间延迟，将对临床实践产生直接和根本的影响。与此项目相关的教育活动将吸引有或没有CP的学生，包括高中、本科和研究生。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个独特的传播工具，“模拟CP”。在“模拟CP”中，典型的发育中的儿童和成人可以在计算机模拟的约束下尝试控制他们的姿势，以适应类似CP的运动结果挑战。总之，本研究项目将结合工程学、参数化建模和临床儿科学来研究严重CP儿童的姿势控制，并通过指导学生和创造新的传播工具来促进该领域的发展。由于闭环姿势控制固有的复杂性，很难识别健康姿势摇摆背后的神经过程。这种困难在患有严重CP的儿童中更加严重，他们缺乏独立的坐姿，也可能有异常的音调或缺乏语言交流。本项目通过利用控制工程来探索中重度CP儿童的姿势系统，克服了这些障碍。研究计划分为三个目标。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。参与者坐在具有可调节主干系统的铰接长凳上，该系统与表面倾斜同步移动，具有高分辨率和准确性。支撑稳定的特定部分的躯干在垂直垂直对齐，同时要求静态，主动和被动的姿态控制以上的支撑部分。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坐姿摇摆参考条件来检查运动学习。数据将在两个不同级别的中继支持下收集：最低级别的中继控制存在，较低级别的中继控制受到挑战。第二个目标是开发实验有效的姿态系统参数模型，解释频率从大约0.04到1.5 Hz的摇摆数据。姿态模型将识别潜在的系统和控制机制，如神经时间延迟、感觉运动噪声、感觉到运动的转换、关节刚度和阻尼，以及控制参数的自适应。不同的模型假设（基于现有的电机控制研究）将被测试。第三个目标是使用相同的实验和建模技术，比较15名6至17岁中度至重度CP（大运动功能分类量表IV级和V级）儿童与年龄匹配的对照组的结果。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.