Proprioceptive Sensorimotor Integration with Neural Interfaces for Hand Prostheses

目前的假体选择并不能满足所有失去上肢肢体的退伍军人的需求。一直以来- 植入的神经接口在提供直观控制和体感反馈方面表现出了希望 假肢使用者。然而，恢复本体感觉，即肢体位置和运动的感觉，通过 神经刺激在很大程度上仍未得到探索。本体感觉是通知和调节运动的关键 控制在健全的人身上，如果没有控制，义肢使用者必须依赖视觉反馈。这样做的目的是 本研究旨在了解外周神经刺激(PNS)对本体感觉的影响。 与假肢控制相结合。中心假设是感觉运动整合在以下情况下是最佳的 本体感觉输入和假体控制方案都与潜在的神经表示相匹配 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本体感觉 失去肢体是上肢假体朝着再次拥有一只手的方向发展的下一个关键步骤。 6名单侧经桡或经肱失去肢体的参与者将植入慢性神经 和肌肉界面。复合平面界面神经电极(C-FINE)将被植入周围 上臂残存的正中神经、尺神经和放射神经。三个经径向置入器将被植入 采用双极肌内肌电(EMG)电极(IMS)对前臂残馀肌肉进行检测。三 经肱骨截肢者将在植入时接受靶向肌肉再神经支配(TMR)手术，并 IMS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 用两年时间完成三个具体研究目标的实验。 在目标1中，将描述由周围神经刺激引起的本体感觉。PNS-引发 感知到的手部运动将通过对侧姿势匹配来跟踪。回归分析将是 执行以确定各种刺激参数对所产生的感知手的贡献 运动学。这些信息将被用来建立一个刺激编码器，以提供时变的本体感觉 信息。还将开发成对的激动剂-拮抗剂PNS策略。激动剂的可区分性- 只有和配对的激动者-拮抗者策略将与心理测量测试进行比较。 在目标2中，三叉神经节的直接肌肉激活在刺激引起的本体感觉上的作用将 接受检查。使用利多卡因注射的神经阻滞将在经桡动脉参与者身上进行 暂时麻醉前臂肌肉。感知运动和肌电活动将在之前进行比较 并对各种三叉神经节刺激后进行运动阻滞。对于将接受TMR的经肱骨参与者，肌肉恢复 神经支配需要3个月左右。比较再手术前后本体感觉和肌电活动的变化。 神经支配完成了。所有参与者都将进行心理测量实验，评估PNS刺激，以及 将比较强直性收缩频率以上和以下的脉冲频率的可识别性。 在目标3中，将评估人工本体感觉与运动控制的整合。以虚拟的姿势 匹配任务时，参与者将利用记录的肌电信号控制一只虚拟手实现目标姿势 来自IMS的。比较了两种控制模式：1)基于位置的控制，其目的是模仿自然 健全个体的手势控制，以及2)基于速度的控制，这是典型的 商业上可以买到的假体。将比较有无刺激诱发的表现 本体感觉反馈。在心理测量不同的评分任务中，参与者将对主观的 不同的刺激-唤起知觉对。一些配对还会包含手部的自发动作 伴随着刺激。评级将在被动和主动本体感觉条件下进行比较 确定自愿控制对刺激诱发知觉的影响。调查以评估具体化和 还将在每次研究会议之前和之后对该机构进行比较。

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.