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

肢体轻瘫（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）被广泛用于辅助虚弱的肢体运动，使神经损伤患者能够更好地参与治疗。虽然它从来没有被证明，FES被认为是促进运动技能再学习，因为它验证了一个人的意图，以肢体运动。如果不是这种情况，参与者可能会通过减少努力并允许FES被动地移动虚弱的肢体而“松懈”，这不利于运动技能的再学习。这个CAREER项目通过开发技术来测量和防止FES辅助治疗期间的懈怠来解决这个问题，这可能会产生广泛的临床影响，因为FES广泛用于康复医学。该项目的教育目标是利用视频游戏制作作为平台，为K-12和大学生提供积极参与康复科学和工程的机会。康复视频游戏的开发将被整合到正在进行的小学，高中和大学学生的科学教育计划中。一个名为“游戏娱乐”的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，一个名为“教育工作者电子刺激”的实验室将培训小学教师向学生介绍康复工程。首席研究员的长期使命是部署基于家庭的虚拟环境治疗，恢复脑损伤患者失去的功能。 为了实现这一使命，该CAREER项目将创建一个依赖于努力的FES援助模式，并证明其在基于任务和基于视频游戏的中风康复过程中保持参与者努力的能力。研究的目的是回答以下问题：如何准确地可以在FES的努力估计？FES协助是否会导致学员在任务练习中松懈？一个依赖于努力的FES控制算法能否在手治疗视频游戏中保持参与者的努力？该项目建立在初步结果的基础上，表明在时变（下降脉冲）FES刺激期间，可以开发方法来提取意志EMG（肌电图）信号，该信号可以用于估计参与者的努力，从EMG信号中也包含由刺激引起的幅度更大的信号。 研究计划有三个目标。 第一个目的是确定如何准确地意志EMG可以估计在时变FES使用现有的方法。 使用从患有慢性中风后偏瘫伴手张开障碍的成年人获得的数据，研究旨在揭示现有的信号处理技术如何消除FES干扰并估计参与者在意志手指伸展努力期间的努力。 第二个目的是表征FES辅助手指伸展努力练习任务时，FES辅助手张开，以确定是否FES援助导致参与者在手指伸展努力松弛，并阐明FES和努力之间的未知关系。 计算EMG闭塞模型将用于创建个人特定的校准，以防止低估努力。 第三个目标是设计一个FES援助模式，保持持续的努力，在任务实践。 该设计包括一个依赖于努力的控制框架，该框架通过募集曲线将非麻痹手张开的程度直接转化为施加到麻痹手的刺激脉冲宽度。这种对侧控制的FES模式（CCFES）将用于研究当FES辅助与意志努力和手张开错误成正比时，在FES辅助手指伸展期间是否可以防止松弛，期望与努力无关的FES相比，努力依赖的FES将增加参与者的努力。虽然该项目的重点是中风后的运动功能恢复，但FES广泛用于康复医学，因此所提出的努力依赖FES模式也有望为脑瘫，脊髓损伤，创伤性脑损伤，运动损伤，该奖项反映了NSF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。

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.