Position sense refers to an aspect of proprioception crucial for motor control and learning. The onset of neurological diseases can damage such sensory afference, with consequent motor disorders dramatically reducing the associated recovery process. In regular clinical practice, assessment of proprioceptive deficits is run by means of clinical scales which do not provide quantitative measurements. However, existing robotic solutions usually do not involve multi-joint movements but are mostly applied to a single proximal or distal joint. The present work provides a testing paradigm for assessing proprioception during coordinated multi-joint distal movements and in presence of kinaesthetic perturbations: we evaluated healthy subjects' ability to match proprioceptive targets along two of the three wrist's degrees of freedom, flexion/extension and abduction/adduction. By introducing rotations along the pronation/supination axis not involved in the matching task, we tested two experimental conditions, which differed in terms of the temporal imposition of the external perturbation: in the first one, the disturbance was provided after the presentation of the proprioceptive target, while in the second one, the rotation of the pronation/ supination axis was imposed during the proprioceptive target presentation. We investigated if (i) the amplitude of the perturbation along the pronation/supination would lead to proprioceptive miscalibration; (ii) the encoding of proprioceptive target, would be influenced by the presentation sequence between the target itself and the rotational disturbance. Eighteen participants were tested by means of a haptic neuroergonomic wrist device: our findings provided evidence that the order of disturbance presentation does not alter proprioceptive acuity. Yet, a further effect has been noticed: proprioception is highly anisotropic and dependent on perturbation amplitude. Unexpectedly, the configuration of the forearm highly influences sensory feedbacks, and significantly alters subjects' performance in matching the proprioceptive targets, defining portions of the wrist workspace where kinaesthetic and proprioceptive acuity are more sensitive. This finding may suggest solutions and applications in multiple fields: from general haptics where, knowing how wrist configuration influences proprioception, might suggest new neuroergonomic solutions in device design, to clinical evaluation after neurological damage, where accurately assessing proprioceptive deficits can dramatically complement regular therapy for a better prediction of the recovery path.

中文翻译：

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机器人在动觉扰动过程中手腕本体感觉的评估：一种神经人体工程学方法

位置感是指本体感受的一个方面，对运动控制和学习至关重要。神经系统疾病的发作会损害这种感觉，从而导致运动障碍，从而极大地减少相关的康复过程。在常规的临床实践中，本体感觉缺陷的评估是通过不提供定量测量的临床量表进行的。但是，现有的机器人解决方案通常不涉及多关节运动，而是大多应用于单个近端或远端关节。本工作提供了一种测试范例，用于评估多关节远侧协调运动和运动觉扰动存在时的本体感受：我们评估了健康受试者沿着三个腕部自由度中的两个自由度匹配本体感受目标的能力，屈曲/伸展和外展/内收。通过沿未参与匹配任务的旋前/旋前轴引入旋转，我们测试了两个实验条件，它们在外部扰动的时间施加方面有所不同：在第一个实验中，扰动是在出现本体感觉后提供的目标，而在第二个目标中，在本体感受目标呈现过程中施加了旋前/旋后轴的旋转。我们研究了（i）沿着旋前/旋前的摄动幅度是否会导致本体感受失调；（ii）本体感受性靶标的编码会受到靶标本身与旋转干扰之间的显示顺序的影响。18位参与者通过触觉神经人体工程学手腕装置进行了测试：我们的发现提供了证据，表明干扰的表现顺序不会改变本体感受敏锐度。然而，已经注意到了进一步的效果：本体感受是高度各向异性的，并且取决于摄动幅度。出乎意料的是，前臂的配置会极大地影响感觉反馈，并显着改变受试者在匹配本体感觉目标时的表现，从而定义了腕部工作区中对运动觉和本体感觉敏锐度更为敏感的部分。这一发现可能会建议在多个领域中解决方案和应用：从一般的触觉（了解腕部配置如何影响本体感受），可能会在设备设计中提出新的神经人体工程学解决方案，再到神经损伤后进行临床评估，