Nason-Tomaszewski Samuel R, Mender Matthew J, Kennedy Eric, Lambrecht Joris M, Kilgore Kevin L, Chiravuri Srinivas, Ganesh Kumar Nishant, Kung Theodore A, Willsey Matthew S, Chestek Cynthia A, Patil Parag G
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, United States of America.
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America.
J Neural Eng. 2023 May 9;20(3). doi: 10.1088/1741-2552/accf36.
Brain-machine interfaces (BMIs) have shown promise in extracting upper extremity movement intention from the thoughts of nonhuman primates and people with tetraplegia. Attempts to restore a user's own hand and arm function have employed functional electrical stimulation (FES), but most work has restored discrete grasps. Little is known about how well FES can control continuous finger movements. Here, we use a low-power brain-controlled functional electrical stimulation (BCFES) system to restore continuous volitional control of finger positions to a monkey with a temporarily paralyzed hand.We delivered a nerve block to the median, radial, and ulnar nerves just proximal to the elbow to simulate finger paralysis, then used a closed-loop BMI to predict finger movements the monkey was attempting to make in two tasks. The BCFES task was one-dimensional in which all fingers moved together, and we used the BMI's predictions to control FES of the monkey's finger muscles. The virtual two-finger task was two-dimensional in which the index finger moved simultaneously and independently from the middle, ring, and small fingers, and we used the BMI's predictions to control movements of virtual fingers, with no FES.In the BCFES task, the monkey improved his success rate to 83% (1.5 s median acquisition time) when using the BCFES system during temporary paralysis from 8.8% (9.5 s median acquisition time, equal to the trial timeout) when attempting to use his temporarily paralyzed hand. In one monkey performing the virtual two-finger task with no FES, we found BMI performance (task success rate and completion time) could be completely recovered following temporary paralysis by executing recalibrated feedback-intention training one time.These results suggest that BCFES can restore continuous finger function during temporary paralysis using existing low-power technologies and brain-control may not be the limiting factor in a BCFES neuroprosthesis.
脑机接口（BMI）已在从非人类灵长类动物和四肢瘫痪患者的思维中提取上肢运动意图方面展现出前景。恢复用户自身手部和手臂功能的尝试采用了功能性电刺激（FES），但大多数工作仅恢复了离散抓握功能。关于FES对连续手指运动的控制效果知之甚少。在此，我们使用一种低功耗脑控功能性电刺激（BCFES）系统，为一只手部暂时瘫痪的猴子恢复对手指位置的连续自主控制。我们在肘部近端对正中神经、桡神经和尺神经进行神经阻滞以模拟手指瘫痪，然后使用闭环BMI预测猴子在两项任务中试图做出的手指运动。BCFES任务是一维的，所有手指一起移动，我们利用BMI的预测结果来控制猴子手指肌肉的FES。虚拟双指任务是二维的，食指与中指、无名指和小指同时且独立地移动，我们利用BMI的预测结果来控制虚拟手指的运动，不使用FES。在BCFES任务中，猴子在手部暂时瘫痪期间使用BCFES系统时，成功率提高到了83%（中位获取时间为1.5秒），而试图使用其暂时瘫痪的手时成功率为8.8%（中位获取时间为9.5秒，等于试验超时）。在一只执行无FES虚拟双指任务的猴子中，我们发现通过执行一次重新校准的反馈意图训练，BMI性能（任务成功率和完成时间）在暂时瘫痪后可完全恢复。这些结果表明，BCFES可以利用现有的低功耗技术在暂时瘫痪期间恢复连续手指功能，并且脑控可能不是BCFES神经假体的限制因素。
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