Proprioceptive Sensorimotor Integration with Neural Interfaces for Hand Prostheses

目前的假肢选择不能满足所有上肢肢体缺失的退伍军人的需求。长期以来- 植入的神经接口已经显示出提供直观控制和体感反馈的希望， 假肢使用者然而，恢复本体感觉，这是肢体位置和运动的感觉，通过 神经刺激在很大程度上仍未被探索。本体感觉对于告知和调节运动是至关重要的 控制在健全的个人，没有它，假肢用户必须依靠视觉反馈。这个目标 本研究旨在了解外周神经刺激（PNS）对本体感觉的感知及其 与假肢控制集成。中心假设是，感觉运动整合将是最好的， 本体感受输入和假肢控制方案都与潜在的神经表征相匹配 在现存的身体图式中的感觉运动过程。为退伍军人提供自然的本体感觉， 肢体丧失是上肢假肢朝着再次拥有手的方向发展的下一个关键步骤。 6名单侧经桡动脉或经肱骨肢体缺失的参与者将植入慢性神经功能缺损， 和肌肉接口。复合扁平界面神经电极（C-FINE）将植入到 上臂的残余正中神经、尺神经和桡神经。三名经桡神经参与者将被植入 用双极肌内肌电图（EMG）电极（IM）在前臂的残余肌肉中。三 经肱骨截肢者将在植入时接受靶向肌肉神经再支配（TMR）手术， IM将被放置在重新神经支配的肌肉中。参与者将每45天参加一次实验室测试会议 用两年时间来完成这项研究的三个具体目标的实验。 在目标1中，将表征由外周神经刺激引起的本体感受感知。PNS诱导 将通过对侧姿势匹配来跟踪所感知的手运动。回归分析将 以确定各种刺激参数对所得到的感知手的贡献 运动学该信息将用于构建刺激编码器，以提供时变本体感受 信息.还将开发成对的激动剂-拮抗剂PNS策略。激动剂的辨别力- 单独和成对的激动剂-拮抗剂策略将与心理测量测试进行比较。 在目的2中，来自PNS的直接肌肉激活对刺激引起的本体感受感知的作用将 接受检查。将对经桡动脉受试者进行利多卡因注射神经阻滞， 暂时麻醉前臂肌肉感知运动和EMG活动将进行比较， 和运动阻滞后的各种PNS刺激。对于将接受TMR的经肱骨参与者，肌肉重建 神经支配需要约3个月。本体感觉和肌电图活动将进行比较之前和之后， 神经支配已完成。所有参与者将进行心理测量实验，评估PNS刺激， 将比较高于和低于强直收缩频率的脉冲频率的可辨别性。 在目标3中，将评估人工本体感觉与运动控制的整合。以虚拟的姿态 匹配任务，参与者将控制一个虚拟的手，以实现目标姿态使用肌电信号记录 从即时消息里两种控制范式将进行比较：1）基于位置的控制，其目的是模仿自然的 身体健全的人的手姿势控制，以及2）基于速度的控制，这是典型的 市售假肢。性能将进行比较，并没有刺激诱发 本体感受反馈在一个心理测量的不同评级任务，参与者将评价主观的 刺激诱发感知对的不相似性。有些对也将包含自愿的手部动作，沿着 与刺激。将比较被动和主动本体感受条件之间的评级， 确定随意控制对刺激诱发感知的影响。调查以评估实施情况， 机构也将在每次研究会议之前和之后进行比较。

Current prosthetic options do not meet the needs of all Veterans with upper extremity limb loss. Chronically- implanted neural interfaces have shown promise for providing intuitive control and somatosensory feedback to prosthesis users. However, restoring proprioception, which is the sense of limb position and movement, via neural stimulation remains largely unexplored. Proprioception is critical for informing and modulating motor control in able-bodied individuals, and without it, prosthesis users must rely on visual feedback. The goal of this study is to understand the perception of proprioception from peripheral nerve stimulation (PNS) and its integration with prosthesis control. The central hypothesis is that sensorimotor integration will be best when both the proprioceptive inputs and the prosthesis control scheme match the underlying neural representations of sensorimotor processes in the extant body schema. Providing natural proprioception to Veterans with upper limb loss is the next critical step in the advancement of upper limb prosthetics toward having a hand again. Six participants with unilateral trans-radial or trans-humeral limb loss will be implanted with chronic neural and muscular interfaces. Composite Flat Interface Nerve Electrodes (C-FINEs) will be implanted around the residual median, ulnar, and radial nerves in the upper arm. Three trans-radial participants will be implanted with bipolar intramuscular electromyography (EMG) electrodes (IMs) in residual muscles in the forearm. Three trans-humeral amputees will receive Targeted Muscle Reinnervation (TMR) surgery at the time of implant and IMs will be placed in re-innervated muscles. Participants will attend laboratory testing sessions every 45 days for two years to complete experiments for the three specific aims of the study. In Aim 1, proprioceptive percepts elicited by peripheral nerve stimulation will be characterized. PNS-elicited perceived hand movements will be tracked through contralateral posture matching. Regression analyses will be performed to determine the contribution of various stimulation parameters on the resulting perceived hand kinematics. This information will be used to build a stimulation encoder to provide time-varying proprioceptive information. Paired agonist-antagonist PNS strategies will also be developed. The discriminability of agonist- only and paired agonist-antagonist strategies will be compared with psychometric tests. In Aim 2, the role of direct muscle activation from PNS on stimulation-elicited proprioceptive percepts will be examined. A nerve block using lidocaine injection will be performed on trans-radial participants to temporarily anesthetize the forearm muscles. Perceived movements and EMG activity will be compared before and after motor block for various PNS stimuli. For trans-humeral participants who will receive TMR, muscle re- innervation takes ~3 months. Proprioceptive percepts and EMG activity will be compared before and after re- innervation is complete. All participants will perform psychometric experiments assessing PNS stimuli, and discriminability will be compared for pulse frequencies above and below tetanic contraction frequency. In Aim 3, the integration of artificial proprioception with motor control will be assessed. In a virtual posture matching task, participants will control a virtual hand to achieve target postures using EMG signals recorded from the IMs. Two control paradigms will be compared: 1) position-based control, which aims to mimic natural hand posture control in able-bodied individuals, and 2) velocity-based control, which is typical for commercially-available prostheses. Performance will be compared with and without stimulation-evoked proprioceptive feedback. In a psychometric dissimilarity rating task, participants will rate the subjective dissimilarity of pairs of stimulation-evoked percepts. Some pairs will also contain voluntary hand motions along with the stimulation. Ratings will be compared between passive and active proprioceptive conditions to determine the effect of voluntary control on stimulation-evoked percepts. Surveys to assess embodiment and agency will also be compared before and after each research session.