The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.
J Neural Eng. 2019 Apr;16(2):026034. doi: 10.1088/1741-2552/ab059b. Epub 2019 Feb 8.
Tactile afferents in the human hand provide fundamental information about hand-environment interactions, which is used by the brain to adapt the motor output to the physical properties of the object being manipulated. A hand amputation disrupts both afferent and efferent pathways from/to the hand, completely invalidating the individual's motor repertoire. Although motor functions may be partially recovered by using a myoelectric prosthesis, providing functionally effective sensory feedback to users of prosthetics is a largely unsolved challenge. While past studies using invasive stimulation suggested that sensory feedback may help in handling fragile objects, none explored the underpinning, relearned, motor coordination during grasping. In this study, we aimed at showing for the first time that intraneural sensory feedback of the grip force (GF) improves the sensorimotor control of a transradial amputee controlling a myoelectric prosthesis.
We performed a longitudinal study testing a single subject (clinical trial registration number NCT02848846). A stacking cups test (CUP) performed over two weeks aimed at measuring the subject's ability to finely regulate the GF applied with the prosthesis. A pick and lift test (PLT), performed at the end of the study, measured the level of motor coordination, and whether the subject transferred the motor skills learned in the CUP to an alien task.
The results show that intraneural sensory feedback increases the subject's ability in regulating the GF and allows for improved performance over time. Additionally, the PLT demonstrated that the subject was able to generalize and transfer her manipulation skills to an unknown task and to improve her motor coordination.
Our findings suggest that intraneural sensory feedback holds the potential of restoring functionally effective tactile feedback. This opens up new possibilities to improve the quality of life of amputees using a neural prosthesis.
人类手部的触觉传入提供了有关手-环境相互作用的基本信息，大脑利用这些信息来调整运动输出以适应被操作物体的物理特性。手部截肢会破坏手的传入和传出通路，完全使个体的运动技能无效。尽管使用肌电假体可以部分恢复运动功能，但为假体使用者提供功能有效的感觉反馈仍然是一个尚未解决的挑战。虽然过去使用侵入性刺激的研究表明，感觉反馈可能有助于处理易碎物体，但没有研究探索抓握过程中重新学习的运动协调。在这项研究中，我们旨在首次展示，对接受经桡骨截肢的个体进行神经内感觉反馈可以改善其对肌电假体的控制，从而提高抓握力的感觉运动控制。
我们进行了一项纵向研究，对一名受试者进行测试（临床试验注册号 NCT02848846）。在两周内进行堆叠杯测试（CUP），旨在测量受试者用假体精细调节握力（GF）的能力。在研究结束时进行的拿起和提起测试（PLT），测量了运动协调水平，以及受试者是否将在 CUP 中学到的运动技能转移到陌生任务中。
结果表明，神经内感觉反馈提高了受试者调节 GF 的能力，并允许随着时间的推移提高性能。此外，PLT 表明，受试者能够将其操纵技能泛化并转移到未知任务中，并提高其运动协调能力。
我们的发现表明，神经内感觉反馈有可能恢复功能有效的触觉反馈。这为使用神经假体改善截肢者的生活质量开辟了新的可能性。
