CAREER: Maintaining volitional effort during electrical stimulation-assisted stroke rehabilitation

肢体瘫痪(由于神经损伤或疾病导致的肌肉无力)影响着数百万患有中风和脑瘫等神经损伤的美国人。功能性电刺激(FES)被广泛用于辅助减弱的肢体运动，以便神经损伤患者能够更好地参与治疗。尽管它从未被证实，但FES被认为可以促进运动技能的重新学习，因为它使一个人的运动意图与肢体运动同步。如果情况并非如此，参与者可能会通过减少努力和允许FES被动移动虚弱的肢体来“松懈”，这不利于运动技能的重新学习。这个职业项目通过开发技术来测量和防止FES辅助治疗中的松弛来解决这个问题，由于FES在康复医学中的广泛应用，这可能会产生广泛的临床影响。该项目的教育目标是以视频游戏制作为平台，为K-12和大学生积极参与康复科学和工程开发机会。康复视频游戏开发将被整合到正在进行的小学、高中和大学生科学教育项目中。一个“功能游戏”项目将培训大学生和高中生为临床医生客户制作视频游戏，一个“教育工作者的E-stim”实验室将培训小学教师向他们的学生介绍康复工程。主要研究人员的长期任务是部署基于家庭的虚拟环境疗法，为脑损伤患者恢复丧失的功能。为了实现这一使命，这个职业项目将创建一种依赖努力的FES援助模式，并展示其在基于任务和基于视频游戏的中风康复期间保持参与者努力的能力。研究旨在回答以下问题：在FES期间，如何准确地估计努力？FES的协助是否会导致参与者在任务练习中松懈？在手部治疗视频游戏中，依赖努力的FES控制算法能维持参与者的努力吗？该项目建立在初步结果的基础上，该结果表明，在时变(下降的脉冲)FES刺激期间，可以开发出从也包含由刺激引起的幅度更大的信号的EMG信号中提取意志EMG(肌电)信号的方法，该信号可用于估计参与者的努力。研究计划是在三个目标下组织的。第一个目标是确定在时变的功能电刺激过程中，使用现有方法可以如何准确地估计意志肌电信号。使用从患有手部张开障碍的慢性中风后偏瘫患者身上获得的数据，研究旨在揭示现有的信号处理技术如何能够很好地消除FES干扰，并估计参与者在自愿伸指努力中的努力。第二个目的是描述FES辅助手部张开练习任务时FES辅助对手指伸展努力的影响，以确定FES辅助是否会导致参与者在伸指努力过程中松懈，并阐明FES和努力之间的未知关系。计算肌电遮挡模型将被用来创建特定于人的校准，以防止低估工作量。第三个目标是设计一种在任务练习期间保持持续努力的FES援助模式。该设计包括一个依赖于努力的控制框架，该框架通过招募曲线将非偏瘫患者手的张开程度直接转换为施加到偏瘫患者手上的刺激脉冲宽度。这种对侧控制的FES通道(CCFES)将被用来研究当FES辅助伸指时，FES辅助与意志努力和手张开错误成正比时，是否可以防止松弛，期望与努力无关的FES相比，努力依赖型FES将增加参与者的努力。虽然该项目关注的是中风后的运动功能恢复，但FES被广泛应用于康复医学，因此，拟议的依赖努力的FES模式也有望为脑瘫、脊髓损伤、创伤性脑损伤、运动损伤和疼痛的患者带来更有效的分娩治疗。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。

Limb paresis (muscular weakness due to nerve damage or disease) affects millions of Americans with neurological injuries such as stroke and cerebral palsy. Functional electrical stimulation (FES) is widely used to assist weakened limb movement so that people with neurological injury can better participate in therapy. Though it has never been proven, FES is thought to promote motor skill relearning because it synchronizes a person’s intent to move with limb movement. If this is not the case, there is a risk that participants can”slack” by reducing effort and allowing FES to passively move the weakened limb, which does not benefit motor skill relearning. This CAREER project addresses this issue by developing techniques to measure and prevent slacking during FES assisted therapy, which could have broad clinical impact as FES is widely used in rehabilitation medicine. The project's educational goal is to use video game production as a platform to develop opportunities for K-12 and college students to actively participate in rehabilitation science and engineering. Rehabilitation video game development will be integrated into ongoing science education programs for primary school, high school, and college students. A “Games for FUNction” program will train college and high school students to create video games for clinician clients and an “E-stim for Educators” lab will train primary school teachers to introduce rehabilitation engineering to their students.The principal investigator’s long-term mission is to deploy home-based virtual environment therapies that restore lost function for people with brain injury. Towards this mission, this CAREER project will create an effort-dependent FES assistance modality and demonstrate its ability to maintain participant effort during task-based and video game-based stroke rehabilitation. Studies are designed to answer the following questions: How accurately can effort be estimated during FES? Does FES assistance cause participants to slack during task practice? Can an effort-dependent FES control algorithm maintain participant effort during hand therapy video games? The project builds on preliminary results showing that, during time-varying (dropped pulses) FES stimulation, methods can be developed to extract volitional EMG (electromyography) signals, which can be used to estimate participant effort, from EMG signals that also contain the much greater in amplitude signal evoked by the stimulation. The Research Plan is organized under three Aims. The FIRST Aim is to determine how accurately volitional EMG can be estimated during time-varying FES using existing methods. Using data obtained from adults with chronic post-stroke hemiplegia with hand opening impairment, studies are designed to reveal how well existing signal processing techniques can eliminate FES interference and estimate participant effort during volitional finger extension efforts. The SECOND Aim is to characterize the effect of FES assistance on finger extension efforts when practicing tasks with FES-assisted hand opening to determine if FES assistance causes participants to slack during finger extension efforts and to shed light on the unknown relationship between FES and effort. Computational EMG occlusion models will be used to create person-specific calibrations to prevent effort underestimation. The THIRD Aim is to design an FES assistance modality that maintains continuous effort during task practice. The design includes an effort-dependent control framework that translates the degree of non-paretic hand opening directly into the stimulation pulse width applied to the paretic hand by way of a recruitment curve. This contralaterally-controlled FES modality (CCFES) will be used to investigate whether slacking can be prevented during FES assisted finger extension when FES assistance is applied in direct proportion to volitional effort and hand opening error, with the expectation that effort dependent FES will increase participant effort compared to effort independent FES. Though this project focuses on motor function recovery following stroke, FES is widely used in rehabilitation medicine, thus the proposed effort-dependent FES modality is also expected to lead to more effective delivery therapy for people with cerebral palsy, spinal cord injury, traumatic brain injury, sports injury, and pain.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.