Closed-Loop Control and Operant Conditioning of Loading Response during Locomotion After Stroke

中风后的人往往挣扎着使用他们的中风影响的腿，以推动自己在行走。由于受影响的腿的部分废用和补偿，人们走路缓慢，更努力。尽管外骨骼技术和机器人步态康复在改善步态能量和速度方面取得了进展，但在腿部功能方面产生持续改善仍然具有挑战性。在中风后的人中，小腿肌肉的激活和产生的力量减少，并且对于行走至关重要的踝关节运动受损。本研究的目的是开发一种新的步态训练方法，通过针对踝关节及其肌肉来增加步行功率，以增强中风影响腿的功能。该项目将使用可穿戴机器人设备对脚踝施加小的运动扰动，以在行走过程中策略性地激活受中风影响的脚踝肌肉。一个独特的条件训练协议将被设计来增加人的脚踝肌肉活动和力量，以推动身体在步行过程中向前。该项目将推进基础知识，以提高肌肉力量和推进力，这是改善中风后步态的关键障碍。教育和外联影响：残疾的初中和高中学生和教师将有机会通过讲习班环境中的实践课程接触可穿戴设备和步态辅助技术。更广泛的外展影响包括一个公共论坛，用于分享该项目的发现，并提高当地中风支持小组的残疾意识。将鼓励代表性不足的群体和少数群体的本科研究人员参加这些培训和传播活动。 该项目旨在通过整合一种新的操作性条件反射协议和机器人踝关节设备来实现神经行为步态训练的范式转变，以增强中风后的瘫痪腿功能。该项目的创新之处在于开发了一种混合方法，以在步行的站立阶段内针对比目鱼肌活动，并调节其负荷反应，作为改善偏瘫步行的策略。该研究计划包括两个目标，即在中风后和身体健全的人中进行测试。目的1研究踝关节跖屈肌在站立相负荷反应的输入输出特性。一个自适应闭环控制算法将被设计和评估应用踝关节旋转使用可穿戴机器人。关节扰动将从自然踝运动学转移到目标比目鱼肌负载响应，即，在站立中晚期激活负荷感受Ib传入。闭环算法将被系统地研究，以定制每个参与者的扰动幅度，速度和定时。在15名中风后参与者的一次跑步机行走过程中，将量化在扰动和未扰动步周期之间比目鱼肌肌电图（EMG）、关节运动学和推进力的变化。来自该目标的发现将提供对通过使用可穿戴设备（即，模仿正常步态期间施加的背屈）。目标2将开发一个动态协议，以提高（操作性条件）比目鱼肌负荷反应在跑步机行走。通过EMG诱发反应的操作性条件反射，参与者将通过视觉反馈增强比目鱼肌负荷反应而获得奖励。将在8名身体健全的个体中实施调节方案，以在6个基线和24个调节会话期间量化比目鱼肌EMG、关节运动学和推进力。从这个目标的发现将有助于推进知识的目标和提高Ib途径的兴奋性，以增加比目鱼肌活动和推进力generation.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Individuals after stroke often struggle to use their stroke-affected leg to propel themselves during walking. Due to this partial disuse of the affected leg and in compensation to that, people walk slowly and with more effort. Despite advances in exoskeleton technologies and robotic gait rehabilitation in improving gait energetics and speed, it remains challenging to yield sustaining improvements in leg function. In people after stroke, the activation of lower leg muscles and generated forces are diminished, and the ankle joint motion that is critically important for walking is impaired. The goal of this project is to develop a novel gait training method to augment the function of the stroke-affected leg by targeting the ankle joint and its muscles to increase walking power. This project will use a wearable robotic device to impose small movement perturbations about the ankle to strategically activate stroke-affected ankle muscles during walking. A unique conditioning training protocol will be designed to increase the person’s ankle muscle activity and force to propel the body forward during walking. This project will advance fundamental knowledge to enhance the muscle power and propulsion, which is a key barrier to improving gait after stroke. Educational and outreach impact: middle and high school students and teachers with disabilities will have opportunities to be exposed to the wearables and gait-assistance technologies through hands-on lessons in a workshop setting. Broader outreach impact includes a public forum for sharing findings from this project and raising disability awareness with people at the local stroke support group. Undergraduate researchers from underrepresented groups and minorities will be encouraged to participate in these training and dissemination activities. This project seeks to achieve a paradigm shift in neuro-behavioral gait training by integrating a novel operant conditioning protocol and a robotic ankle device to enhance paretic leg function post-stroke. The innovation in this project is the development of a hybrid approach to target the soleus muscle activity within the stance phase of walking and condition its loading response as a strategy to improve hemiparetic walking. The research plan includes two objectives with testing in people post-stroke and able-bodied individuals. Objective 1 will characterize the input-output property of the ankle plantarflexors’ loading response in stance phase. An adaptive closed-loop control algorithm will be designed and evaluated to apply ankle joint rotations using the wearable robot. The joint perturbations will be shifted from the natural ankle kinematics to target the soleus loading response, i.e., activate load sensing Ib afferents, in mid-late stance phase. The closed-loop algorithm will be systematically investigated to customize the perturbation magnitude, speed, and timing for each participant. Changes in soleus electromyography (EMG), joint kinematics, and propulsion will be quantified between perturbed and unperturbed step cycles during one treadmill walking session in 15 participants post-stroke. Findings from this objective will provide insights into the methods to modulate the soleus loading response by manipulating ankle kinematics through applied, controlled joint perturbations using the wearable device (i.e., emulate imposed dorsiflexions during normal gait). Objective 2 will develop a dynamic protocol to enhance (operantly up-condition) the soleus loading response during treadmill walking. With operant conditioning of the EMG evoked response, participants will be rewarded for enhancing the soleus loading response through visual feedback. The conditioning protocol will be implemented in 8 able-bodied individuals to quantify soleus EMG, joint kinematics, and propulsion throughout 6 baseline and 24 conditioning sessions. Findings from this objective will help to advance the knowledge to target and enhance the excitability of Ib pathways to increasing soleus activity and propulsive force generation.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.