Neural Interface and Control Design to Restore Sensation in Amputees

描述 基本原理：标准上肢假体是一种基于线缆的系统，其中附接到假体的线缆围绕背部缠绕到对侧肩部。通过操纵对侧肩部，使用者控制假体的功能，例如抓握或释放物体，以及由假体施加的力。虽然不是自然的，但用户确实从电缆中产生的张力量接收到一种形式的感官反馈。近年来，肌电假体已经变得可用。这些较新的假肢依靠截肢的残余肌肉的自主收缩来控制假肢的功能。虽然肌电假肢比传统的基于电缆的系统更美观，并提供更大的运动范围，但它们缺乏感觉反馈。由于手是操纵外部环境的关键，因此上肢的感觉反馈至关重要。理想的人工感觉反馈机制应该是能够产生与非截肢肢体完全相同的感知。虽然感觉感受器在截肢中缺失，但曾经携带感觉信息的神经通路保持完整，并且可以通过电刺激兴奋，从而为截肢者提供感觉反馈的机会。目的：本研究的目的是证明，以受控的方式施加到截肢者的残余神经的电刺激可以提供可以调制的感觉反馈，并且是可再现的。此外，这项研究旨在证明，电刺激引起的感觉是稳定的，随着时间的推移，他们的位置可以人为 而不改变刺激参数。许多假设将通过一系列跨越10周时间的实验进行测试。研究计划和方法：5名受试者将在其手臂的残余神经周围植入神经袖带电极：正中神经、桡神经、尺神经和肌皮神经。在研究的前四周，将以粗略、快速的方式搜索刺激空间。最有希望的刺激参数及其周围的空间将在未来6周内进行更详细的测试。将询问受试者对刺激的感知以及这些感知如何随时间或刺激参数的变化而变化。通过使受试者与对侧完整肢体镜像位置来研究肢体位置改变的感觉。将使用Vicon系统记录肢体位置。除了制作一个刺激-感受图（可能随时间而变化）之外，还将挑选一个感受者，以便人为地重新安置。这将通过刺激神经和诱导与受试者所看到的不一致的感知来实现。具体来说，压力将施加到指尖， 在用已知在其他地方引起感觉的一组刺激参数刺激受试者的神经的同时，视觉反馈应允许受试者将感知的位置“调整”到指尖。成功的感觉重新定位可以让一个完美的映射，从一个临床医生希望刺激被感知到的地方和受试者实际感知到的地方。除了在研究过程中收集的数据，这将导致两个手稿，一个软件包将存在，允许快速，高效，有意义的刺激优化在研究结束时。该软件将是有用的，在未来的研究，包括额外的刺激通道或位置。在这项研究中获得的数据将指导未来的阶段，其中假体的设计，以控制感觉反馈和受试者的能力，以执行任务的日常生活与感觉反馈进行评估。

DESCRIPTION Rationale: The standard upper extremity prosthesis has been a cable-based system in which cables attached to the prosthesis wrap around the back to the contralateral shoulder. By manipulating the contralateral shoulder, the user controls the function of the prosthesis, such as gripping or releasing an object, as well as the force that is applied by the prosthesis. While not natural, the user does receive a form of sensory feedback from the amount of tension developed in the cables. In more recent years, myoelectric prostheses have become available. These newer prostheses rely on voluntary contraction of the residual muscles of the amputated limb to control the function of the prosthesis. While myoelectric prostheses are more cosmetically pleasing and provide a greater range of motion than the traditional cable-based system, they lack sensory feedback. Because the hands are key for manipulating the external environment, sensory feedback is critical in the upper extremities. The ideal artificial sensory feedback mechanism would be one that produces the exact same perception as the non-amputated limb. Although the sensory receptors are missing in the amputated limb, the neural pathways that once carried sensory information remain intact and can be excited with electrical stimulation, thus affording an opportunity for providing sensory feedback to the amputee. Objective: The objective of this study is to prove that electrical stimulation applied to the residal nerves in an amputee in a controlled manner can provide sensory feedback that can be modulated and is reproducible. Further, this study aims to demonstrate that the sensations induced by electrical stimulation are stable over time and that their locations can be artificially manipulated without altering stimulus parameters. Numerous hypotheses will be tested through a series of experiments that span a 10 week time period. Research Plan and Methodology: Five subjects will be implanted with nerve cuff electrodes around residual nerves in their arm: the median, radial, ulnar, and musculocutaenous nerves. Stimulus space will be searched in a gross, rapid manner over the first four weeks of the study. The most promising stimulus parameters and the space surrounding them will be tested in more detail during the next 6 weeks. Subjects will be queried for their perceptions to stimulation and how those perceptions change with time or with changes in stimulus parameters. Sensations that the limb has changed position will be studied by having the subject mirror the position with the contralateral, intact limb. Limb positions will be recorded with a Vicon system. In addition to creating a stimulus-to-percept map, which may vary over time, a percept will be singled out for the purpose of artificial relocation. This will be accomplished by stimulating the nerve and inducing a percept that is in disagreement with what the subject sees. Specifically, pressure will be applied to the fingertip of the subject's prosthesis at the same time that the subject's nerve is stimulated with a set of stimulus parameters known to induce a sensation somewhere else. The visual feedback should allow the subject to "adjust" the location of the perception to the fingertip. Successful relocatio of a sensation may allow a perfect mapping from where a clinician wants a stimulus to be perceived and where the subject actually perceives it. In addition to the data gathered during the study, which will lead to two manuscripts, a software package will exist that allows fast, efficien, and meaningful stimulus optimization at the conclusion of the study. This software will be useful in future studies that incorporate additional stimulus channels or locations. The data obtained in this study will guide a future phase in which a prosthesis is designed to control sensory feedback and the subject's ability to perform tasks of daily living with the sensory feedback is evaluated.