Department of Bioengineering, University of Utah, Salt Lake City, UT, 84112, USA.
Department of Neurosurgery, University of Utah, Salt Lake City, UT, 84132, USA.
J Neuroeng Rehabil. 2017 Nov 25;14(1):121. doi: 10.1186/s12984-017-0320-4.
Despite advances in sophisticated robotic hands, intuitive control of and sensory feedback from these prostheses has been limited to only 3-degrees-of-freedom (DOF) with 2 sensory percepts in closed-loop control. A Utah Slanted Electrode Array (USEA) has been used in the past to provide up to 81 sensory percepts for human amputees. Here, we report on the advanced capabilities of multiple USEAs implanted in the residual peripheral arm nerves of human amputees for restoring control of 5 DOF and sensation of up to 131 proprioceptive and cutaneous hand sensory percepts. We also demonstrate that USEA-restored sensory percepts provide a useful source of feedback during closed-loop virtual prosthetic hand control.
Two 100-channel USEAs were implanted for 4-5 weeks, one each in the median and ulnar arm nerves of two human subjects with prior long-duration upper-arm amputations. Intended finger and wrist positions were decoded from neuronal firing patterns via a modified Kalman filter, allowing subjects to control many movements of a virtual prosthetic hand. Additionally, USEA microstimulation was used to evoke numerous sensory percepts spanning the phantom hand. Closed-loop control was achieved by stimulating via an electrode of the ulnar-nerve USEA while recording and decoding movement via the median-nerve USEA.
Subjects controlled up to 12 degrees-of-freedom during informal, 'freeform' online movement decode sessions, and experienced up to 131 USEA-evoked proprioceptive and cutaneous sensations spanning the phantom hand. Independent control was achieved for a 5-DOF real-time decode that included flexion/extension of the thumb, index, middle, and ring fingers, and the wrist. Proportional control was achieved for a 4-DOF real-time decode. One subject used a USEA-evoked hand sensation as feedback to complete a 1-DOF closed-loop virtual-hand movement task. There were no observed long-term functional deficits due to the USEA implants.
Implantation of high-channel-count USEAs enables multi-degree-of-freedom control of virtual prosthetic hand movement and restoration of a rich selection of both proprioceptive and cutaneous sensory percepts spanning the hand during the short 4-5 week post-implant period. Future USEA use in longer-term implants and in closed-loop may enable restoration of many of the capabilities of an intact hand while contributing to a meaningful embodiment of the prosthesis.
尽管先进的机器人手取得了进展，但这些假肢的直观控制和感觉反馈仅限于闭环控制中的 3 自由度（DOF）和 2 种感觉知觉。过去，犹他倾斜电极阵列（USEA）已用于为人类截肢者提供多达 81 种感觉知觉。在这里，我们报告了在人类截肢者残留的周围臂神经中植入多个 USEA 可恢复对 5 DOF 的控制和多达 131 种本体感觉和皮肤手感觉知觉的高级功能。我们还证明，USEA 恢复的感觉知觉在闭环虚拟假肢手控制期间提供了有用的反馈源。
将两个 100 通道的 USEA 植入两个先前进行过长时间上臂截肢的人类受试者的正中神经和尺神经中，每个神经各一个。通过修改后的卡尔曼滤波器从神经元放电模式解码预期的手指和手腕位置，使受试者能够控制虚拟假肢手的许多运动。此外，USEA 微刺激用于引发遍及幻影手的许多感觉知觉。通过尺神经 USEA 的电极刺激来实现闭环控制，同时通过正中神经 USEA 记录和解码运动。
受试者在非正式的“自由形式”在线运动解码会议期间控制了多达 12 个自由度，并体验了多达 131 种 USEA 引发的遍及幻影手的本体感觉和皮肤感觉。实现了包括拇指、食指、中指、环指和手腕的 5-DOF 实时解码的独立控制。实现了 4-DOF 实时解码的比例控制。一名受试者使用 USEA 引发的手部感觉作为反馈来完成 1-DOF 闭环虚拟手部运动任务。由于 USEA 植入物，没有观察到长期功能缺陷。
高通道数 USEA 的植入可实现虚拟假肢手运动的多自由度控制，并在植入后短短的 4-5 周内恢复遍及手部的丰富选择的本体感觉和皮肤感觉知觉。未来在长期植入物和闭环中的 USEA 使用可能会恢复完整手的许多功能，同时为假肢的有意义体现做出贡献。
