Restoration of Reach and Grasp in Stroke Patients using Electrical Stimulation and Haptic Feedback

当你练习打网球时，你会变得更好，因为你的大脑和脊髓中已经建立了新的神经连接。你不仅需要练习，你还需要对你的表现进行反馈，这样你才能纠正你的动作。在这项研究中，我们使用这个想法来教中风患者如何学习新的技能。当人们在中风后重新学习技能时，他们会经历与你学习打网球时相同的过程。但他们有一个问题。因为连接他们大脑和肌肉的一些神经受损，他们几乎不能动。因此，他们无法练习，这意味着他们得不到反馈。肌肉可以通过电刺激通向肌肉的神经来工作。电脉冲沿神经传播的方式与来自大脑的电脉冲相似。如果仔细控制刺激，就能做出有用的动作。如果人自己尝试运动，效果会更好；因此，我们需要将人自己的努力与刚刚足够的额外电刺激结合起来，才能实现运动。在之前的一个研究项目中，我们设计并测试了控制算法(用于调节刺激的规则)，以在简单的伸展任务中刺激一块肌肉。我们要求患者在光点离开他们身体时用他们的手跟踪它。他们的前臂放在一个水平支撑物上，这个支撑物从桌子上滑过，他们的手绕着一根竖杆弯曲。当他们移动时，我们刺激伸展他们肘部肌肉的肌肉。在每次尝试之后，我们使用规则来调整下一次刺激的水平和时间，以提高它们的跟踪能力。经过五次尝试，患者几乎可以完美地跟踪光点。然后他们继续练习；如果他们跟踪得很好，那么下一次他们从刺激中得到的帮助就会更少。这被称为迭代学习，它模拟了大脑学习新技能的方式。一项针对5名中风患者的研究表明，这有助于他们重新学习移动手臂，但他们并没有更好地执行日常任务。为了做到这一点，我们认为我们需要通过3D让任务变得更加“真实”，包括张开手、握住和伸手。这需要刺激肩部、肘部、手腕和手指的肌肉。追踪一束光也很无聊，而且不会给出你在现实生活中所经历的“触摸”反馈。因此，患者不会跟踪一个光点，而是玩一个虚拟现实电脑游戏，当他们成功地抓住一个虚拟物体时，他们将获得对指尖的感觉刺激。为了让游戏更有趣，我们会调整难度，让它更具挑战性，给人一种成功和进步的感觉。设计控制算法来调整对多个肌肉的刺激，使它们能够执行现实生活中的任务，提供适当和及时的感觉反馈，并调整‘游戏’是本项目的目标。这些是为实现我们的目标而采取的步骤。首先，为了设计规则，我们将创建手臂和手的数学模型，以预测它将如何反应，并考虑到痉挛(某些肌肉的非自愿过度活动)和疲劳等情况。然后我们设计算法--这是该项目最具挑战性的部分。为了提供感官或触觉反馈，我们将改装一种商用手套(无需重新发明)，添加传感器，将手套中的信息与算法联系起来，使患者易于戴上和脱下手套。在整个项目中，我们将与患者、治疗师和其他人交谈，以确保我们创造的东西是适合用途的。每种成分都将在健康人和中风患者身上进行测试。这项实验工作将在一项为期8周的临床试验中达到高潮，涉及5到8名中风患者。

When you practice playing tennis you become better at it, because new nerve connections have been made within your brain and spinal cord. Not only do you need to practice, but you also need feedback of your performance so that you can correct your movement. In this research we are using this idea to teach people who have had a stroke how to learn new skills. When people re-learn skills after a stroke they go through the same process as you do when you learn to play tennis. But they have a problem. Because some of the nerves connecting their brain and their muscles have been damaged they can hardly move at all. Consequently they cannot practice which means they don't get feedback. Muscles can be made to work by Electrical Stimulation of the nerves leading to them. Electrical impulses travel along nerves in a similar way to electrical impulses from your brain. If stimulation is carefully controlled, a useful movement can be made. This works better if the person is attempting the movement themselves; we therefore need to combine a person's own effort with just enough extra electrical stimulation to achieve the movement. In a previous research project we designed and tested control algorithms (rules used to regulate stimulation) to stimulate one muscle during a simple reaching task. We asked patients to track a spot of light with their hand as it moved away from their body. Their forearm rested on a horizontal support that glided over a table and their hand was curved around a vertical bar. As they moved we stimulated the muscle that extended their elbow muscle. After each attempt we used the 'rules' to adjust the level and timing of the stimulation on the next to improve their tracking. After five attempts patients could track the spot of light almost perfectly. They then continued to practice; if they tracked the spot well, then the next time they got less help from the stimulation. This is called Iterative Learning and it models the way the brain learns new skills.A study with 5 stroke patients showed that it helped them to relearn to move their arm, but they didn't get much better at performing everyday tasks. To do this we believe we need to make the tasks more 'real' by being 3D and include opening the hand and grasping as well as reaching. This requires stimulating the muscles of the shoulder, elbow, wrist and fingers. Tracking a spot of light is also boring and does not give the 'touch' feedback that you experience in real-life. So, rather than tracking a spot of light, patients will play a virtual reality computer game and when they successfully grasp a virtual object they will get a sensory stimulus to the finger tips. To the make the games more fun we will adjust the level of difficulty so make it challenging and give a feeling of success and progress. To design control algorithms to adjust stimulation to multiple muscles so that they can perform real-life tasks, provide appropriate and timely sensory feedback and adjust the 'game' is the goal of this project. These are the steps to be taken to achieve our goal. Firstly, to design the rules, we will create a mathematical model of the arm and hand to predict how it will respond, taking into account things like spasticity (involuntary over-activity in some muscles) and fatigue. We then design the algorithms - this is the most challenging part of the project. To provide the sensory or 'haptic' feedback we will adapt a commercially available glove (no need to re-invent this) adding sensors, linking the information from the glove to the algorithm and making the glove easy for patients to put on and take off. Throughout the project we will talk to patients, therapists and others to make sure what we create is fit-for-purpose. Each component will be tested with healthy people and those who have had a stroke. The experimental work will culminate in an 8-week clinical trial involving between five and eight stroke patients.