Sensory feedback for prosthesis control is typically based on encoding sensory information in specific types of sensory stimuli that the users interpret to adjust the control of the prosthesis. However, in physiological conditions, the afferent feedback received from peripheral nerves is not only processed consciously but also modulates spinal reflex loops that contribute to the neural information driving muscles. Spinal pathways are relevant for sensory-motor integration, but they are commonly not leveraged for prosthesis control. We propose an approach to improve sensory-motor integration for prosthesis control based on modulating the excitability of spinal circuits through the vibration of tendons in a closed loop with muscle activity. We measured muscle signals in healthy participants and amputees during different motor tasks, and we closed the loop by applying vibration on tendons connected to the muscles, which modulated the excitability of motor neurons. The control signals to the prosthesis were thus the combination of voluntary control and additional spinal reflex inputs induced by tendon vibration. Results showed that closed-loop tendon vibration was able to modulate the neural drive to the muscles. When closed-loop tendon vibration was used, participants could achieve similar or better control performance in interfaces using muscle activation than without stimulation. Stimulation could even improve prosthetic grasping in amputees. Overall, our results indicate that closed-loop tendon vibration can integrate spinal reflex pathways in the myocontrol system and open the possibility of incorporating natural feedback loops in prosthesis control.

中文翻译：

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手假肢感觉运动控制中自然脊髓反射环路的激发


用于假肢控制的感官反馈通常基于对特定类型的感官刺激中的感官信息进行编码，用户解释这些信息以调整假肢的控制。然而，在生理条件下，从周围神经接收到的传入反馈不仅会被有意识地处理，还会调节脊髓反射环，从而有助于驱动肌肉的神经信息。脊髓通路与感觉运动整合相关，但它们通常不用于假肢控制。我们提出了一种改善假肢控制的感觉运动整合的方法，该方法基于通过肌肉活动闭环中肌腱的振动来调节脊柱回路的兴奋性。我们测量了健康参与者和截肢者在不同运动任务期间的肌肉信号，并通过对与肌肉相连的肌腱施加振动来闭合循环，从而调节运动神经元的兴奋性。因此，假肢的控制信号是自愿控制和由肌腱振动引起的额外脊髓反射输入的组合。结果表明，闭环肌腱振动能够调节肌肉的神经驱动。当使用闭环肌腱振动时，与没有刺激的情况相比，参与者可以在使用肌肉激活的界面中实现相似或更好的控制性能。刺激甚至可以改善截肢者的假肢抓握能力。总的来说，我们的结果表明，闭环肌腱振动可以将脊髓反射通路整合到肌肉控制系统中，并为将自然反馈回路纳入假肢控制提供了可能性。