Engels Leonard F, Shehata Ahmed W, Scheme Erik J, Sensinger Jonathon W, Cipriani Christian
The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.
Division of Physical Medicine and Rehabilitation, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
Front Neurosci. 2019 Jun 6;13:578. doi: 10.3389/fnins.2019.00578. eCollection 2019.
State of the art myoelectric hand prostheses can restore some feedforward motor function to their users, but they cannot yet restore sensory feedback. It has been shown, using psychophysical tests, that multi-modal sensory feedback is readily used in the formation of the users' representation of the control task in their central nervous system - their internal model. Hence, to fully describe the effect of providing feedback to prosthesis users, not only should functional outcomes be assessed, but so should the internal model. In this study, we compare the complex interactions between two different feedback types, as well as a combination of the two, on the internal model, and the functional performance of naïve participants without limb difference. We show that adding complementary audio biofeedback to visual feedback enables the development of a significantly stronger internal model for controlling a myoelectric hand compared to visual feedback alone, but adding discrete vibrotactile feedback to vision does not. Both types of feedback, however, improved the functional grasping abilities to a similar degree. Contrary to our expectations, when both types of feedback are combined, the discrete vibrotactile feedback seems to dominate the continuous audio feedback. This finding indicates that simply adding sensory information may not necessarily enhance the formation of the internal model in the short term. In fact, it could even degrade it. These results support our argument that assessment of the internal model is crucial to understanding the effects of any type of feedback, although we cannot be sure that the metrics used here describe the internal model exhaustively. Furthermore, all the feedback types tested herein have been proven to provide significant functional benefits to the participants using a myoelectrically controlled robotic hand. This article, therefore, proposes a crucial conceptual and methodological addition to the evaluation of sensory feedback for upper limb prostheses - the internal model - as well as new types of feedback that promise to significantly and considerably improve functional prosthesis control.
目前最先进的肌电假手可以为使用者恢复一些前馈运动功能，但尚无法恢复感觉反馈。通过心理物理学测试已经表明，多模态感觉反馈很容易用于使用者在中枢神经系统中形成对控制任务的表征——他们的内部模型。因此，为了全面描述向假肢使用者提供反馈的效果，不仅应该评估功能结果，还应该评估内部模型。在本研究中，我们比较了两种不同反馈类型以及两者组合对内部模型和无肢体差异的新手参与者功能表现的复杂相互作用。我们发现，与仅使用视觉反馈相比，在视觉反馈中添加互补音频生物反馈能够显著增强用于控制肌电假手的内部模型，但在视觉反馈中添加离散振动触觉反馈则不能。然而，两种反馈类型在相似程度上都改善了功能性抓握能力。与我们的预期相反，当两种反馈类型结合时，离散振动触觉反馈似乎主导了连续音频反馈。这一发现表明，简单地添加感觉信息在短期内不一定会增强内部模型的形成。事实上，它甚至可能使其退化。这些结果支持了我们的观点，即评估内部模型对于理解任何类型反馈的效果至关重要，尽管我们不能确定这里使用的指标是否详尽地描述了内部模型。此外，本文测试的所有反馈类型都已被证明能为使用肌电控制机器人手的参与者带来显著的功能益处。因此，本文提出了对上肢假肢感觉反馈评估的一个关键概念和方法补充——内部模型，以及有望显著且大幅改善假肢功能控制的新型反馈。
